CIS-Electronic Fuel Injection
 Alt rights reserved. All information contained in this publication is based on the latest
product information available at the time of printing. The right is reserved to make
changes at any time without notice. No part of this publication may be reproduced, stored
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published in Canada. All rights reserved under Bern and Pan-American Copyright
Conventions.
Index
Basic System Operation
Mixture Control Unit
Differential Pressure Regulator
Fuel Supply Diagram
Fuel Pump
Accumulator
Fuel Filters
Pressure Regulator
Cold Starting
Cold Running Controls
Electronic Control Unit
Sensor Plate Potentiometer
Temperature Sensor
After Start Eprichment
Warm-Up Enrichment
Acceleration Enrichment
Oxygen Sensor
Altitude Compensation
Full Throttle Enrichment
Deceleration Fuel Shut-Off
Test Procedures
Basic Checks and Adjustments
Pressure Testing
System Operational Checks
Sensor Plate Checking, Adjusting
Potentiometer Checking, Adjusting
Cold Start Valve/Thermo-time Switch Checking
Auxiliary Air Regulator Checking
Throttle Valve Position Checking
Fuel Pump Delivery
Injector Bench Testing
Injector Quality Testing
Idle Air Stabilization Valve Checking
Electrical Testing
Functional Diagrams
Glossary
32
37
40
44
48
50
51
52
53
53
54
56
57
60
63
Copyright 1984
à VOLKSWAGEN OF AMERICA INC.-SERVICE TRAINING
+4 ated in U.S.A.-First Edition
BASIC SYSTEM
Fuel injector
Differential
pressure regulator
Fuel distributor 1! | + -
Air Flow Sensor — E 3 (= вет ~
Plate |
Pressure
regulator
CIS electronic is a further development of the familiar CIS system and shares
many of the same basic principles of operation. The following changes have been
made to further refine the system:
e Elimination of the frequency valve and control pressure regulator.
These two components have been replaced by a differential
pressure regulator (electro-hydraulic actuator) which is attached to
the fuel distributor and operated by an electronic control unit.
» A separate fuel pressure regulator to govern system pressure. This
resulted in a redesigned fuel distributor and elimination of the
pressure relief valve in the fuel distributor.
* A single electronic control unit that incorporates all the fuel system
functions and includes the oxygen sensor system.
e Expanded functions of the fuel system which, on many cars,
include:
— Starting enrichment
— After-start enrichment
— Warm-up enrichment
— Acceleration enrichment
— Full load enrichment
— Altitude correction
— Deceleration fuel shut-off
MIXTURE CONTROL UNIT
The mixture control unit is located between
the air cleaner and the throttle vaive. It
consists of the air sensor and the fuel
distributor.
The air sensor measures the amount of air
entering the engine and controls the amount
of fuel injected by moving the control plunger
in the fuel distributor.
The flow of intake air through the air cone will
lift the sensor plate causing the sensor lever
to lift the control plunger in the fuel distributor.
As the control plunger rises, it allows more fuel
to be delivered to the injectors.
Since the air sensor is constantly measuring
the intake air and controlling the amount of
fuel by raising or lowering the control plunger,
the basic air/fuel mixture is always correct.
BASIC SYSTEM
AIR SENSOR
- a
air cone —
—
air flow
T= Ja |
NY
FUEL DISTRIBUTOR
control
sensor plate
pivot
sensor lever
>
BASIC SYSTEM
The pictures below show the relationship between
air flow and fuel flow:
control
plunger
I
>=
sensor plate
air cone — |
“e
air flow
pivot
sensor lever
ES
EE
ee
AIR
AB)
об” full
2 EN load
— co
l a © @
_J pa
= pe load
= e
+ P (1)
idie
AIR FLOW
balance
weight
The operation of the air sensor is based on the
“floating body principle” which says that a
floating body suspended in a cone moves in a
straight line according to the rate of air flow
through the cone.
The CIS electronic “floating body” is the
circular sensor plate bolted to the sensor lever
which moves freely around a pivot point. The
movement of the sensor plate, lever and
control plunger are controlied and dampened
by a balance weight at the end of the lever and
system pressure acting on the top of the
control plunger.
At (1), the slight air flow at idle lifts the sensor
plate enough to raise the control plunger
slightly. The metering slit in the fuel distributor
Is opened to aliow enough fuel for idie.
As air flow increases, more of the metering slit
is exposed (2) until at full throttle (3), the fuel
flow is at maximum.
The graph represents an engine's basic
air-fuel requirement.
Notice that with CIS electronic fuel injection
the fuel flow is automatically corrected for any
volume of air flow from idle throughout the full
load range.
The sensor plate position has been changed
because of the new fuel distributor. The
control plunger now seats on an O-ring. There
Is now a small gap between the sensor lever
and the control plunger when the sensor lever
is at rest position. This is necessary to insure
that the plunger seals completely against the
O-ring when the engine is shut off. This results
in the sensor plate resting below the edge of
the sensor housing. When the engine is not
running, the sensor plate and lever rest on a
spring loaded stop.
The control plunger sits low enough to
uncover the top edge of the metering slits.
This allows residual system pressure to work
directly on the injectors to eliminate fuel
vaporization.
Should a backfire occur in the intake manifold,
the sensor plate will be forced down against
the spring loaded stop. This creates a larger
opening around the sensor plate to reduce
pressure and to prevent damage to the air
sensor assembly.
BASIC SYSTEM
Control
plunger
Sensor plate rests
about 2mm below edge
O-ring
Backfire
BASIC SYSTEM
BASIC SYSTEM
Directional
shield
Plastic
shroud
Filter Circlip
Circlip
Directional
shield
FUEL INJECTORS
CIS injectors open at a pre-set pressure and
spray atomized fuel continuously into the
intake port near each intake valve.
When the engine is stopped, the fuel pressure
is reduced and the pin and spring assembly at
the end of the injector closes. This traps fuel
under pressure in the system to prevent vapor
lock and to insure quick hot starting.
All engines are now equipped with air
shrouded injectors. Air flows through a
passage in the cylinder head, through the
injector insert and exits near the tip of the
injector. The fuel leaving the injector is better
atomized, reducing fuel condensation in the
intake manifold.
There is now a second generation of air
shrouded injectors. The changes consist of: A
circlip added to the injector to hold the sealing
“O” ring in position; a new brass injector insert;
a separate plastic injector shroud; and a fluted
air directional shield attached to the end of the
injector to improve air flow around the injector
nozzle. These changes enhance the fuel
atomization and provide even smoother
engine performance.
The new style 2 piece insert assembly must
only be used together with the new injectors
that have the directional shield attached to the
nozzle. This complete assembly may be
installed in earlier vehicles with air shrouded
injectors.
FUEL DISTRIBUTOR
Control Plunger
To Cold
To Fuel Injector
|
Start Valve
From
Fuel
Pump
|
To Pressure a. 2
Regulator
Restrictor
System Pressure
soma Lower Chamber
Eu E Pressure
*
The fuel distributor has many changes to
adapt it to CIS electronic. It is now made of
aluminum and is slightly smaller than previous
versions. Some of the changes are:
e Deletion of pressure relief valve.
e The pressure regulating springs are now in the
lower chambers and the differential pressure
regulator (electro-hydraulic actuator) is
mounted directly to the fuel distributor.
¢ The volume of the upper chamber is smaller,
resulting in quicker response and good hot
starting.
Se df
CaO
LT j
EA
Spill Volume
Return to
Pressure
Regulator
Control Plunger
Seat with Ring
Upper Chamber
Pressure Regulating Valve
— ) Differential pressure
uy regulator
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i
Л
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Tran) x ON Coils
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и y
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7
= ER
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Pressure Valve Plate Pivot
Regulating
Spring Valve Plate
Lower
Chamber
* The control plunger now seats on an O-ring
with the engine shut-off. There is now a few
millimeters play between the sensor plate
arm and the control plunger with the engine
shut-off.
System pressure is always present in the
upper chamber of the fuel distributor. The
metering slit in the control barrel regulates the
amount of fuel delivered to the upper chamber
based on air sensor position and control
plunger position. The amount of fuel delivered
to the injectors, and consequently the fuel
mixture, is adjusted by the differential pressure
regulator.
DIFFERENTIAL PRESSURE REGULATOR
(ELECTRO-HYDRAULIC ACTUATOR)
Coils Permanent
+
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ay
=
+.
LIC
+
a
EC
1.7
LL
Tey
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"a
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wp
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к я
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че
тк
Valve plate
fr,
— pivot
BASIC SYSTEM
Plate Г
S
System L ‘ :
pressure i
from чо
иррег 1
chamber i
Inlet
E System pressure
sens Lower chamber
EE pressure
The differential pressure regulator is bolted to
the side of the fuel distributor. It consists of a
plate valve fastened between two
electromagnets. The plate valve regulates the
fuel flow into the lower chamber of the fuel
distributor. This determines the differential
pressure, which is the difference in pressure
between the upper and lower chambers in the
fuel distributor.
By varying the electric current to the differential
pressure regulator and changing the strength
of the magnets, the plate valve can be moved.
By changing the opening, the quantity of fuel
aliowed into the lower chamber of the fuel
distributor can be regulated. This in turn
changes differential pressure.
The differential pressure regulator operating
current is supplied by the control unit and is
measured in milliamps.
8
7
44m = mg
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BEER Ao
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wn
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ew
.=
aw
Permanent
magnet
The operating range is from -50 to +150mA.
Differential pressure will be from O bar to about
1.6 bar (24 PSI) less than system pressure.
The differential pressure regulator is
constructed so that without any operating
current, such as in an electrical failure, the
plate valve wouid deflect enough under
system pressure to maintain a differential
pressure of about 0.4 bar. This combined with
the 0.2 bar difference caused by the pressure
regulating springs in the fuel distributor will
result in a difference of 0.2 bar between the
upper and lower chambers in the fuel
distributor. Since this pressure difference is the
same as on the earlier CIS system, the car will
still be driveable in the event of an electrical
failure. However, it will run roughly because of
the resultant lean air/fuel mixture.
BASIC SYSTEM
E Cu O
Mixture contro! works like this: based on
electrical current supplied to the differential
pressure regulator, the valve plate deflects,
thereby regulating differential pressure. The
pressure difference controls the amount of fuel
delivered to the injectors.
When the current supplied to the differential
pressure regulator is increased, the plate valve
deflects to the right and restricts the flow of fuel
to the lower chamber causing the pressure
regulating valves to deflect downward. The
resultis increased fuel flow to the injectors and
a richer air/fuel ratio.
When the current supplied to the differential
pressure regulator is reduced, the plate valve
moves to the left and allows more fuel into the
lower chamber. The pressure in the lower
chamber increases and deflects the pressure
regulating valves upward. The quantity of fuel
to the injectors is consequently reduced
resulting in a leaner air/fuel mixture.
The graph shows the relationship between
differential pressure regulator current and the
pressure in the lower chamber of the fuel
distributor. As current is increased or reduced,
the lower chamber pressure is controlled to
regulate the fuel flow to the injectors.
The pressure shown is the difference between
system pressure in the upper chamber of the
fuel distributor, and the pressure in the lower
chamber.
Plate
valve Г
Fuel quantity
to injectors
increased
!
E
Plate
valve |
(mA)
120-
100-
BD .
a
Lower chamber pressure
Fuel quantity
lo iIméclors
reduced
+
| | Pressure
| | regulating
1 | valves
Tr
1.2
1.4
1.6 (bar)
9
FUEL SUPPLY
Fuel injector
Differential pressure
нете стор l'equlator
- A PA FET
Cold
start valve
—
Fuel
accumulator
The fuel supply for the CIS electronic system
consists of a fuel tank, fuel pump, accumulator,
fuel filter, and fuel distributor. The pump delivers
fuel from the tank, through a fuel accumulator
and filter to the fuel distributor.
Fuel distnbutor |]
4
q 3
© Pressure
regulator
Li
5
fii
EEE
Fuel filter С
” “
«li
к A
Electric Fuel tank
fuel pump
The fuel system pressure is determined by a
diaphragm type fuel pressure regulator.
Differential pressure in the lower chamber of
the fuel distributor is determined by differential
pressure regulator plate valve position.
Excess fuel from the fuel distributor returns to
the fuel tank through return lines at a very
low pressure.
FUEL SUPPLY
FUEL PUMP
The roller-cell fuel pump is driven by a
permanent magnet electric motor that is
located near or inside the fuel tank.
Steel rollers are held in “cut-outs”” on the
rotor. Centrifugal force seals the rollers
against the walls of the pressure chamber as
the rotor spins. Fuel that is trapped between
the rollers is then forced out the delivery port.
The pump is designed to be both cooled and
lubricated by the fuel flowing through it.
Since there is never a combustible mixture
inside the pump, there is no possibility of fire.
The pump is subject to damage if it is ever
allowed to run “dry.” +
À non-replaceable relief valve is designed to
vent fuel back to the intake side of the pump if
pressure ever exceeds the normal pressure
range.
[5
A replaceable check-valve holds about 2 bar
of residual pressure in the system with the
engine shut off and seals in conjunction with
the pressure regulator to insure quick
hot-starting.
Since the pump delivers a greater amount of
fuel than is required by the engine at any given
time, excess fuel is diverted back to the tank
via the pressure regulator, which is located
near the fuel distributor.
Some vehicles are equipped with a transfer
pump located in the fuel tank and attached to
the fuel tank sending unit. This pump delivers
fuel to a separate reservoir which supplies the
fuel for the main fuel pump.
Fuel out
Î
Check valve Relief valve
Fuel in
Ef
q Roller-cell
Armature
Fuel in
|
Rollers
Cross section of
roller cell
in fuel pump
ROTOR
;
Through pump
To Return
From engine from
transfer pump engine
compartment
Return to tank
> '
1. Fuel tank
2. Sending unit with transfer pump
3. Fuel supply reservoir
4. Fuel pump
5. Accumulator
10
11
FUEL SUPPLY
ACCUMULATOR
FUEL SUPPLY
~3 Reed valve
«==> To filter
| Г
Damper plate
Bleed hole
Stop Diaphragm
«io From pump
The accumulator is located between the fuel
pump and the fuel filter. When the fuel pump is
running, the diaphragm moves to the stop
against spring pressure. When the fuel pump
is off, the fuel is stored under pressure in the
accumulator thereby maintaining residual
fuel pressure.
The accumulator reduces fuel pump noise as
well as protecting the metal diaphragm in the
fuel distributor from rapid pressure build-up
when the pump begins to run.
SYSTEM PRESSURE
0 05 10 1.5
seconds
When the fuel pump begins running, the fuel
chamber inside the accumulator is filied
through the one-way reed valve, and the
diaphragm is forced to the left against the
spring until it reaches the stop. Only after the
diaphragm reaches the stop does system
pressure reach its operating limit.
RESIDUAL PRESSURE
Pressure
4 Curve
2
HEN
0 10 20 30 40 50 minutes
with accumulator
without accumulator _ _ ____. —
After the engine is turned off, the spring slowly
pushes the diaphragm to the right, forcing
about 20cc of fuel through a small hole in the
reed valve to help maintain residual fuel
pressure and avoid fuel vapor lock.
FUEL FILTERS
The fuel filter removes particles from the fuel
that might otherwise clog the fuel distributor or
injectors.
It is located on the pressure side of the pump
so that a possible clogged filter will not
damage the pump by causing it to run “dry.”
The nylon-paper element inside the filter
housing is designed to work best with the fuel
flowing in one direction. An arrow on the fuel
filter housing denotes the correct installation.
“
A filter/strainer is also located on the fuel
pick-up inside the tank. On vehicles with the
transfer pump in the fuel tank, there is a
strainer attached to the end of the pump.
Tank
sending
unit
Transfer
There is a mini fuel filter located in the hollow
bolt that connects the pressure line to the
fuel distributor.
For replacement intervals for all filters, refer
to the maintenance schedule for each partic-
ular vehicle.
Mini Fuel Filter
in Union Bolt N ES
12
13
FUEL SUPPLY
PRESSURE REGULATOR/ENGINE RUNNING
verni
Regulating
Regulating e
spring
Return _ date
PARSE AE
isis
НН
Stop — ня
Return from LL SLA ZA
lower chamber | TE
distributor Sr
Fra”, ne +
System pressure [132%
TO Pressure
Because of the additional electronic controls a
control pressure regulator and pressure relief
valve are no longer needed. Instead, a
diaphragm type pressure regulator is used to
maintain system pressure at approximately
5.4 bar (78.3 PSI).
When the engine is started fuel enters from
the main return of the fuel distributor and
works against the regulating spring. The
Return to
fuel tamk
Diaphragm
ATA Main return
SR from fuel
me DS, I
Bani distributor
Valve body
sealing plate
Closing pressure
spring
diaphragm assembly moves up along with the
valve body which is moved by the closing
pressure spring to open the sealing plate. The
valve body then contacts its stop and the
regulation of system pressure will begin via
the regulating valve. The excess fuel along
with the spill volume from the lower chamber
in the fuel distributor is now returned back to
the fuel tank via the opened sealing plate.
FUEL SUPPLY
PRESSURE REGULATOR/ENGINE SHUT-OFF
Regulating Spring
A Nos Diaphragm
E se E.
HET DORIA
ci E ae
— y Valve Body
So
— Sealing Plate
Retum to
Fuel Tank
The pressure regulator also acts as one way When the engine is shut off the regulating
check valve to maintain pressure in the system spring will push the diaphragm and valve
once the engine has been shut off. It works body down. This will close the sealing plate
like this. and shut off the return passageway to the
tank thereby maintaining residual pressure
in the system.
SE. DSF N N DL Si нана Га
14
15
COLD STARTING CONTROLS
ALL 4 CYLINDER ENGINES
50
. Cold
start valve
Thermo-time
switch
50
During cold starting a cold start valve, which is
located in the intake manifold, provides
necessary fuel enrichment to all cylinders. The
electro-magnetic coil in the cold start valve
receives current from the starter. It is
af
a:
bl
— 2 ar = i
$
*
Y
grounded by the thermo-time switch so that
the injector sprays only during cranking. The
thermo-time switch controls the cold start
valve so that the engine will not flood if it fails
to start immediately.
na
COLD STARTING CONTROLS
COLD START VALVE
Fuel in
y |
The cold start valve is an electrically operated Mil a | ;
solenoid valve. e E =
When voltage is applied, fuel is sprayed | = Solenoid coil
directly into the intake manifold. = d bt Seal
When the valve is not energized, it closes and | f = Plunger
seals. =i. oy
Swirl nozzle
” THERMO-TIME SWITCH —
Plug socket — |
The thermo-time switch senses engine Housing
temperature and controls the cold start valve
according to temperature and time.
Bi-metal strip 1
Heating coil — ==
Contact points ]
COLD START VALVE WIRING
To starter ol e
Terminal 50
The cold start valve is wired so that it opens for
several seconds when the starter is activated Cold start
and the thermo-time switch provides a ground Valve
(cold engine).
Thermo-time
Switch
16
17
COLD STARTING CONTROLS
FE
QUANTUM 5 CYLINDER
Thermo-time
switch
Electronic
control unit
Fuel delivered by the cold start valve is
supplemented by additional starting
enrichment on some vehicles. This is
accomplished in the following manner.
When the starter is activated the control unit
increases the current to the differential
pressure regulator and the fuel mixture is
enriched. The amount of starting enrichment is
COLD RUNNING CONTROLS
dependent upon engine coolant temperature.
Maximum starting enrichment time is 1.5
seconds, during which time current to the
differential pressure regulator can briefly go as
high as 150 mA if the engine is cold. Starting
enrichment will also occur with warm engine
starting, but is at its greatest level when the
engine is cold.
ALL 4 CYLINDER ENGINES EXCEPT GTI AND GLI
Fuel injector
Temperature
Sensor
Fuel distributor |
15
Auxiliary air
regulator
*
Electronic
control unit
o
Bi-metal strip
À
Dan
Electric
heating
element
|
= A Pivot
(1 Gate Valve
e: ко
_
a
F A
Ч /
Once the cold engine has started, the
auxiliary air regulator acts like a “fast idle
cam’’ to slightly increase idle speed while the
engine is warming up.
The auxiliary air regulator provides additional
air for idling during warm up.
When the engine is cold, the gate valve is
open and air can bypass the closed throttle
valve.
After the engine is started, the electric heating
element warms the bi-metal strip which
gradually closes the gate valve.
19
ee ЧЩ
COLD RUNNING CONTROLS
QUANTUM 5 CYLINDER, GTI AND GLI
Fuel injector
Differential
TH
BR,
Na
— dle air
O |k
| valve
Temperalure |
sensor |
Air-flow sensor | amo Li
potentiometer
stabilization
E
Yi
Electronic
control umit
| ©
The Quantum 5 cylinder, the GTI and the GLI
use an idle air stabilization system in place of
the auxiliary air regulator. This system insures
that idle speed remains at about 1000 RPM
during cold engine operation.
| рт,
The circuitry for controlling the idle air
stabilization valve is incorporated in the fuel
injection control unit and is influenced by a
signal from the temperature sensor in the
engine coolant.
This system insures that the idle speed
remains constant at predetermined levels
during all engine operating conditions.
The system maintains the following idle RPM
for these conditions.
e Engine cold (less than 50°C) =
approximately 1000 RPM
¢ Engine warm (above 50°C) = approximately
850 RPM
¢ Engine warm and A/C compressor engaged
= approximately 900 RPM
The idle air stabilization valve, which
eliminates the auxiliary air regulator,
consists of an electric motor with two
windings and a turning angle of about 90°.
The valve is operated by a cycled voltage
signal which is generated by the control unit.
By regulating the rate of the voltage signal,
the valve position can be controlled,
resulting in the idle speed being maintained
at a predetermined level.
The cycled voltage signal is the same as the
signal used to operate a frequency valve in
earlier CIS injection systems. A test plug,
identical to that of the oxygen sensor system,
is located in the engine compartment to test
and adjust the system.
The operating range of the system is from
about 20% to 80% (18° to 72°).
IDLE AIR STABILIZATION
Throttle valve
| À
N
NE
Idle air stabilization
valve
| From A/C compressor
injection rom idle switch
eg control
unit From coolant temperature
sensor
Electrical connection
CL HE
AE
u
Air regulating
valve
ELECTRICAL CONTROLS
Sensor plate
potentiometer
‘Minimum voltage signal
N — ==
6V +
sv +
a+
IV —
2V —
Air-flow sensor
1У = lever angle
ov | |
5 10 15
CONTROL UNIT
A 25 pin control unit determines the electronic
operation for the fuel injection system. It receives
the following inputs:
e Engine temperature
e Engine speed (Quantum 5 cyl., GTI, and GLI)
e Sensor plate position
e Throttle position (Quantum 5 cyl., GTI and
GLI)
e Oxygen sensor
e Starter signal
e Atmospheric pressure (Quantum 5 cyl. only)
The control unit generates output signals to the
differential pressure regulator based on these
inputs, thereby providing the proper air/fuel
mixture for all engine operating conditions.
| SENSOR PLATE POTENTIOMETER
The sensor plate assembly now uses a
potentiometer to measure the position of the
sensor plate. ltis attached to the side of the air
sensor housing.
The potentiometer consists of a wiper brush
working on a carbon film. It sends a variable
voltage signal to the control unit based on
sensor plate position. This signal is supplied
primarily for cold acceleration enrichment.
—— 03 A =
ELECTRICAL CONTROLS
COOLANT TEMPERATURE SENSOR
The coolant temperature sensor is threaded
into the bottom of the cylinder head coolant
outlet and senses the temperature of the
coolant.
The sensor is a negative temperature
coefficient (NTC)resistor, which means that its
resistance decreases as coolant temperature
increases {see graph).
A signal from the temperature sensor enables
the control unit to provide additional fuel to the
injectors.during starting and engine warm-up.
The lower the temperature of the coolant, the
more fuel that is provided to the engine.
The graph illustrates that temperature sensor
resistance decreases gradually during engine
warm-up so that the air/fuel mixture is correct
for all operating temperatures.
50000
40000
30000
20000
10000
6000
6000
4000
3000
2000
R(O)
1000
Resistance curve
-30-20 0 20 40 60 80 100 120°C
Temperature
23
ELECTRICAL CONTROLS ELECTRICAL CONTROLS
AFTER-START ENRICHMENT AND OXYGEN SENSOR
WARM-UP ENRICHMENT |
Increase
Differential
pressure
| regulator
| Î
Decrease
Time
current
|
|
|
| Increase
№
Differential
pressure
current
Е
Decrease
Amount of enrichment
dependant on coolant temperature
After the engine has started the control unit
continues to enrich the mixture through
increased differential pressure regulator
current. This insures that the engine runs
smoothly whenitis cold. The level of after-start
enrichment is dependent on engine coolant
temperature, and lasts approximately 40
seconds. While the engine is warming-up, fuel
enrichment continues based on coolant
temperature. This warm-up enrichment
continues at a lower level than after-start
enrichment and decreases as the engine
reaches operating temperature. The following
graph illustrates these functions.
Starting
enrichment
(Quantum 5 cyl.)
- 30°C
After-start
enrichment
enrichment
ACCELERATION ENRICHMENT
Maximum enrichment possible
20°C 80°C
Acceleration enrichment will also only take
place when the engine is below normal
operating temperature and is only effective for
a few seconds. The amount of acceleration
enrichment is dependent upon:
* Engine coolant temperature
* Movement speed of the sensor plate
* Total travel of the sensor plate
The resistance curve of the sensor plate
potentiometer is such that the rate of
enrichment is greater at lower engine speed
and less at higher engine speed.
Differential
pressure regulator
H
Air-flow sensor E E AE
potentiometer
Temperature
WW sensor
Electronic
control unit
Y
Oxygen
sensor
An oxygen sensor system with a 3-way
catalytic converter is used on all cars with CIS
Electronic Fuel Injection.
A separate oxygen sensor control unit and
frequency valve are not needed. Instead, once
the engine reaches operating temperature the
control unit processes the voltage signal from
the oxygen sensor and adjusts the differential
pressure regulator current accordingly. The
operating range of the differential pressure
regulator during oxygen sensor regulation is
from O to 20 mA.
E
On vehicles with CIS electronic fuel injection,
the oxygen sensor sends a varying voltage
signal to the control unit based on the amount
of oxygen in the exhaust. The control unit then
signals the differential pressure regulator
which changes the quantity of fuel delivered to
the injectors.
25
ELECTRICAL CONTROLS
ELECTRICAL CONTROLS
=
Platinum coated outer surface
Platinum coated inner surface
Exhaust gas Ceramic material
TA
WA
=D
O
Outside air
Heating
element
connection
Heating supply
voltage
Oxygen sensor
supply voltage
PETE af
> 5
A » ia
e
LA
Heating element
“ 26
The oxygen sensor is made of a ceramic
material called Zirconium dioxide. The inner
and outer surfaces of the ceramic material are
coated with platinum. The outer platinum
surface is exposed to the exhaust gas, while
the inner surface is exposed to the outside air.
The difference in the amount of oxygen
contacting the inner and outer surfaces of the
sensor creates a pressure differential which
results in a small voltage signal of between 175
to 1100 mV being supplied to the control unit. A
high voltage signal indicates a rich mixture,
and if the mixture is lean, a low voltage signal
will be sent to the control unit.
On the GTI and GLI, the oxygen sensor is
heated electrically to keep it at a constant
operating temperature. This insures
continuous and accurate reaction of the
sensor during all operating conditions.
The heated oxygen sensor has three wires,
two for the heating element (ground and
power) anda signal wire for the oxygen sensor.
Power is supplied to the heating element
whenever the engine is running.
*
The oxygen sensor system operates like this. If
the amount of oxygen in the exhaust system is
low, indicating a rich mixture, the sensor
voltage will be high. This signal, about 1100
mV, is sent to the control unit. The electronic
control unit then reduces the current signal to
the differential pressure regulator.
When the current to the differential pressure
regulator is reduced the plate valve will move
to the left and allow more fuel into the lower
chamber. The pressure in the lower chamber
will then increase and deflect the pressure
regulating valves upward. The quantity of fuel
delivered to the injectors is then reduced and
the fuel mixture is leaded.
If the mixture is lean, the oxygen sensor will
send a low voltage signal of about 175 mV to
the electronic control unit. The control unit will
increase the current to the differential pressure
regulator.
When current to the differential pressure
regulator is increased, the plate valve will
deflect to the right and restrict the flow of fuel to
the lower chamber. This reduces the pressure
in the lower chamber causing the pressure
regulating valves to deflect downward. The
resultis increased fuel flow to the injectors and
an enriched fuel mixture.
Fuel quantity
to injectors
reduced
Plate _
valve
vos System pressure
Lower chamber pressure
Fuel quantity
to injectors
increased
Plate
valve |
Pressure
_—- regulating
valves
27
ELECTRICAL CONTROLS ELECTRICAL CONTROLS
и
ALTITUDE CORRECTION FULL THROTTLE ENRICHMENT
The Quantum 5 cyl., GTI, and GLI are When engine speed is above 4000 RPM, and
Altitude Quantums with 5 cylinder engines use an
equipped with full throttle enrichment. Full the throttle is fully open, the full throttle switch,
sensor altitude sensor that is mounted next to the
control unit. This sensor is used to send a
voltage signal to the control unit that is based
throttle enrichment will only take place after
the engine has reached operating temperature
and provides additional fuel for the increased
located on the throttle housing, closes sending
a voltage signal to the electronic control unit.
The control unitincreases differential pressure
on altitude. The signal is used to adjust the fuel
mixture for changes in air pressure. The | performance requirements of the engine. regulator current to a fixed rate that is
altitude compensation function operates in the approximately 3 mA above the basic
following manner. adjustment value to enrich the fuel mixture.
DECELERATION FUEL SHUT-OFF
Fuel to injectors
In areas of high altitude the air pressure is
tower than at sea level. This results in the air
being ‘thinner’ or less dense, which means Plate valve shut-off 5
the engine will have less oxygen to burn. The Quantum 5 cyl., GTI and GLI also fully № À |] system pressure
| Under this condition, the altitude sensor sends incorporate a deceleration fuel shut-off feature
to help improve fuel economy. During engine |
deceleration, the contfol unit reverses the
current to the differential pressure regulator to
about -40 mA. This opens the plate valve and
allows system pressure to work on the lower
a resistance signal to the control unit. This
resistance signal results in a lower current
being sent to the differential pressure
regulator. As a result, less fuel is delivered to
the engine to maintain the correct air/fuel ratio.
Regulating
"7 valves closed
. = P
chambers. System pressure combined with - regulating
the pressure regulating springs closes the Springs
In areas below sea level, air pressure is higher
than at sea level. This results in the air being
regulating valves and shuts off the flow of fuel —|
Т
| Change in differential pressure regulator current = about more dense, which means there is more to the Injectors.
| 1A per 1000 fi. etevation change oxygen available to support combustion. If not Engine RPM
|| compensated for, this extra oxygen would \
| resultin a lean air/fuel mixture. In this instance, 3600 77 \ == === Fuel shut-off begins
| +2mA the altitude sensor sends a voltage signal to \
oma the control unit which then increases the | 3400 + = Fuel shutoff ends
2mA current to the differential pressure regulator lo Insure that the fuet shut off feature
| and the mixture is enriched. operates smoothly, the point at which shut-off 3000 +
begins and ends is influenced by engine
-6mA At sea level the sensor is open and has no coolant temperature. If the engine is below 2600 +
effect on the fuel mixture. The change in operating temperature, the cut-in and cut-off
40mA differential pressure regulator current is points are raised accordingly. Whenthe — 2200 +
effective in all operating modes of the fuel e engine is at operating temperature cut-off will
1000 © 1000 2000 3000 4000 5000 injection system. The graph illustrates the occur when: 1800 +
Below Above (feet) amount of altitude compensation. A |
sea level sea level * Engine speed is above approximately 1600 1400 +
RPM
e The throttle is closed 1000 +
Fuel flów to the injectors will be resumed when 0 НЕ | | |
engine speed drops below approximately 1300
RPM.
-30° -10" 0° 10° 30° 50° 70° 90° 110%
Engine Temperature
SYMPTOM GROUPS
SYMPTOM GROUPS
Test procedures for CIS electronic
components are explained in the following
section of this book. Depending on the
symptoms, the problem may fall into one of
the following categories 1) Cold Starting, 2)
Hot Starting, 3) Cold Running, and 4) Warm
Running.
COLD STARTING
Symptom:
* Cold engine does not start
e Cold engine difficult to start
Preliminary Checks:
e Starting procedure OK
| e Cranking speed OK
e [gnition system OK
| * Compression OK
Check:
* Timing, idle speed, CO% (pp. 32-36)
e Cold start valve/thermo-time switch (pg. 50)
e System operational checks (pp. 40-41)
e Sensor plate height, center and clearance
(pp. 44-45, 47)
e Sensor plate — check for binding (pg. 46)
HOT STARTING
Symptom:
* Warm engine does not start
* Warm engine difficult to start
Preliminary Checks:
e Starting procedure OK
e Cranking speed OK
e Cranking time (within 10 seconds) OK
e Ignition system OK
* Compression OK
* Intake system leaks (hoses/boots/injector
seals and inserts etc.)
Fi EF
Check:
* Timing, idle speed, CO% (pp. 32-36)
* Oxygen sensor system operation (pp. 41-42)
* Residual pressure (pg. 40)
* Sensor plate height, center and clearance
(pp. 44-45, 47)
* Injector bench test, Injector quantity
(pp. 53-55)
* Fuel pump delivery (pg. 53)
COLD RUNNING
Symptom:
* Cold engine starts and stalls
* Cold engine runs poorly
Preliminary Checks:
e Starting procedure OK
e Ignition system OK
* Compression OK
¢ Vacuum hose routing OK
® Intake system leaks (hoses/boots/injector
seals & inserts etc.)
de
Check:
* Timing, idle speed, CO% (pp. 32-36)
o Auxiliary air regulator (pg. 51)
* Sensor plate — center (pg. 47)
* Oxygen sensor system — operation
(pp. 41-42)
e Sensor plate — check for binding (pg. 46)
e Differential pressure (Il) (pp. 38-39)
Potentiometer (pa. 48)
e System operational checks (pp. 40-41)
System pressure (pg. 37)
Altitude compensation device (Quantum 5
cyl.) (pg. 43)
* |dle air stabilization checks (Quantum 5 cyl.
GTI and GLI) (pg. 56)
WARM RUNNING
re
Symptom:
e Warm engine runs poorty
Preliminary Checks:
e [gnition system OK
* Compression OK
® Vacuum hose routing OK
* Intake system leaks (hoses/boots/injector
seals & inserts etc.)
Check:
* Timing, idle speed, CO% (pp. 32-36)
e System pressure (pg. 37)
e Oxygen sensor system — operation
(pp. 41-42)
e Injector quantity, injector bench test
(pp. 53-55)
* Fuel pump delivery (pg. 53)
* Sensor plate — center (pg. 47)
* Sensor plate — check for binding (pg. 46)
* Altitude compensation device (Quantum 5
cyl.) (pg. 43)
¢ Differential pressure (1) (pg. 38)
Basic throttle position (pg. 52)
Idle air stabilization checks (Quantum 5 cyl.
GTI, and GLI) (pg. 56)
31
BASIC CHECKS AND ADJUSTMENTS
CHECKING 4 CYLINDER ENGINES (EXCEPT GTI AND GLI)
Siemens 451 or VW 1367 |
* Engine oil temperature minimum 80° C
(176° F)
o All electrical consumers switched off
* Oxygen sensor connected
* Connect engine tester according to
manufacturer's instructions
| 910 |
|
87 NS
(000000)
* Pinch supply hose for idle air bypass valves
¢ Remove cap from CO probe receptacle
e Connect CO tester to probe receptacle
Hose must fit snugly so there is no exhaust
leak
® Remove wiring connector from the
differential pressure regulator
* Connect adaptor VW 1315 A/1 and
multimeter US 1119 between the differential
pressure regulator and the wiring connector
|
Set multimeter to 200 mA scale
Note: ° ,
TDC sending unit must fit С Start engine
snugly into transmission housing
ML)
* Check idle speed
900 +100RPM
| e Check ignition timing
6° + 2° BTDC
* Check differential pressure regulator current
10 mA + 6 mA and fluctuating
* Check CO%
0.3% to 1.2%
e If within specifications, shut off engine and
continue with fuel system pressure checks
VW 1315 A/1
Tester
US1119
O e
e If not within specifications, continue with
adjusting procedure
Differential
pressure
regulator
32
Wiring
connector
ее ран
BASIC CHECKS AND ADJUSTMENTS
TE N — o
ADJUSTING 4 CYLINDER ENGINES (EXCEPT GTI AND GLI)
Crankcase vent
hoses removed
“T” connection from
carbon canister
e Remove “T” connection from carbon
canister at intake air boot.
e Turn”T” piece 90” and insert blank side with
1.5mm restrictor into hole in intake air boot.
NOTE: if caris not equipped with this type
of connector, use part
# 026-133-382) or equivalent plug
with 1.5mm orifice.
e Remove both crankcase vent hoses and
vent to atmosphere.‘
e Start engine
e Adjust idle speed
900 + 30 RPM
e Adjust timing
6° + 1° BTDC
e Adjust differential pressure regulator
current
10 + 1 mA and fluctuating
e Check CO%
0.3% to 1.2%
e Note that the current reading should
fluctuate within the specified range
e Acurrent reading that does not fluctuate
indicates a problem with the oxygen sensor
system
e Readjust idle speed if necessary
33
BASIC CHECKS and ADJUSTMENTS BASIC CHECKS and ADJUSTMENTS
CHECKING QUANTUM 5 CYLINDER, GTI AND GLI
¢ Reconnect engine tester to make idle RPM * Check CO%
Engine oil temperature minimum 80° C and ignition timing checks 0.3% to 1.2%
(17°) e Start engine e Check differential pressure regulator
* All electrical consumers switched off e Check idle RPM current
* Oxygen sensor connected | 800+ 50 RPM for Quantum GTI and GLI — 10mA + emA
* Remove cap from CO probe receptacle 850 +100 REM for GTI and GLI Quantum — refer to graph below
* Connect CO tester * Check ignition timing e ¡fall values are within specifications shut off
Hose must fit snugly so that there is no 6° + 2° BTDC engine and continue wi fue system
exhaust leak a oe
* |f all values are not within specifications,
* Remove wiring connector from differential continue with adjusting procedure
pressure regulator
| VW 1315 A/1 * Connect adaptor VW 1315 A/1 and
| multimeter US1119
Set multimeter to 200 mA scale
* Connect engine tester to test plug using
Wiring adaptor US1112 and set tester to 4
connector a
Lo cylinder scale
| у
16mA
Differential
pressure
regulator
. 12mA —
Differential
pressure
regulator
current
NOTE: Only connect the (+) and (—) and 8mA
||| (dwell) leads of VW 1367 or Siemens
451. If other test leads are connected
the “duty cycle” readings for the idle AMA
air stabilization valve will be
inaccurate. 1000 0 1000 2000 3000 4000
Below e zu Above
sea level (feet) sea level
e Start engine
e Check duty cycle of idle air stabilization
valve
28% + 2% (23° -&7°)
e Shut off engine
Adapter US 1112
BASIC CHECKS and ADJUSTMENTS
PRESSURE CHECKS
ы
НО
ADJUSTING QUANTUM 5 CYLINDER, GTI AND GLI
e Remove cap from carbon canister purge
line
Note: On Golf and Jetta, remove carbon
canister purge line (see page 33)
æ E,
e Disconnect crankcase breather hoses and
vent to atmosphere
— Ч
Note: On Quantum 5 cylinder, disconnect
both crankcase breather hoses from valve
| cover and plug both T connections at valve
| cover.
e Connect engine tester using adaptor
US1112 and 4 cylinder scale
e Start engine
e Adjust duty cycle of idle air stabilization
valve to:
28% + 1%(25 = 1°)
RPM should be 800 +50 RPM
e Shut off engine
Reconnect engine tester to continue with
ignition timing and CO% adjustments
Start engine
Adjust ignition timing
6° + 1° BTDC
Adjust CO%
GTI and GLI — 10mA + {mA with
oxygen sensor
connected.
Quantum — 0.8% + 0.2% with
oxygen sensor
disconnected.
Differential pressure regulator
current must correspond to
graph. If not, see page 43.
Note: Current reading must fluctuate when
oxygen sensor is connected. If not,
check oxygen sensor system.
If CO% can not be adjusted to
specified range check engine
condition (intake leaks, exhaust
leaks, etc.).
т.ч.
Y
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e - ны Aa e A tada, safle. Ed
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+ PA Ell ape Ja +
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16mA
ve
12mA —— ba an
LO TA LF +, и]
Dviterental E | ARIA E
pressure â {>
regulator a+
curreril AZ
8mA
dmA | ———
+
a, oF
+:
rie,
1000
Below
BEA Level
ul —]]]]N ZZ
|
|
| } |
0 1000 2000 3000 4000
Bea beng
SYSTEM PRESSURE
* Connect VW 1318 pressure gauge between
the fuel line at the cold start valve and lower
chamber test connection on the fuel
distributor
¢ Use adaptor VW 1318/5 on lower fuel chamber
connection
5 cylinder
fuel distributor
4 cylinder
fuel distributor
Lower
chamber 8
test plug
Lower
chamber
test plug +
Front of car
Front of car
Md
* Remove fuel pump relay and jump socket
with US 4480/3
* Remove wiring connector from differential
pressure regulator
* Open valve on VW 1318 pressure gauge
* Energize fuel pump
System pressure should be 5.2 to 5.6 bar (75 to
82 PSI)
NOTE: System pressure is not adjustable.
o |f system pressure is incorrect, check:
Fuel pump delivery quantity
Fuel supply and return lines for restrictions
Fuel filters
e |f pressure is still incorrect, replace pressure
regulator and retest system pressure
С,
|
—
L
|
ДВ. C=
me:
+ <
fe
” ДИН
y VW 1318
“©
+
Line to cold start
To Cold Start
Valve Fuel Line
Pressure
Regulator
37
PRESSURE CHECKS PRESSURE CHECKS
fp ————— : Te —— = те
DIFFERENTIAL PRESSURE (PART |) DIFFERENTIAL PRESSURE (PART 11) CONTINUED
* Close valve on VW 1318 pressure gauge e Connect 15K Q side of tool 1490 to
(wiring connector for differential pressure temperature sensor wiring connector.
regulator remains disconnected) rm Side remains disconnected
Energize fuel pump | e Turn ignition on À \\
| Differential pressure should be 0.2 to 0.5 bar | * Energize fuel pump X =
| (2.9to 7.0 PSI) less than previously measured Differential pressure should be 0.7 to 1.2 bar UD
| System pressure (10 to 17.5 PSI) less than previously Temperature sensor
| e |f not within specifications replace differential measured system pressure
| pressure regulator and retest Differential pressure regulator current 7 IN
| Valve Closed e If still not within specifications replace should be 50 to 80 mA ) | ef
» » 1 re
fuel distributor e If amperage is within specifications but — Ч oh N ca la —
pressure is not within specifications, replace J | N
differential pressure regulator = S NN £
e If pressure and amperage readings are not IN
within specifications:
DIFFERENTIAL PRESSURE (PART II) Check ground wire of temperature sensor at
cold start valve
If ground is OK, check all electrical
e Connect adapter VW1315 A/1 between connections (see page 58)
differential pressure regulator and wiring _
connector If all wiring and connections are OK, replace
| control unit
| e Connect multimeter US1119 to adaptor
| VW 1315 A/1
Set to 200 mA scale
¢ Remove wiring connector from engine coolant
| temperature sensor
| VW 1315 AN
der
|
| Differential 5 6 Wiri
pressure ring
| regulator connector SE
|
PRESSURE CHECKS
SYSTEM OPERATIONAL CHECKS
RESIDUAL PRESSURE
VW 1318
NOTE: The residual pressure check does not
include the cold start valve. To check,
reattach fuel line, energize fuel pump,
and check valve visually for leaks.
SYSTEM OPERATIONAL CHECKS
WARM-UP ENRICHMENT
e Remove wiring connector from engine
coolant temperature sensor and leave
disconnected
e Turn ignition on
Differential pressure regulator current
should be 80 to 110 mA
e |f out of specification, check wiring
(see page 58)
e |f wiring is OK, replace control unit
e Open valve of VW 1318
e Energize fuel pump for 30 seconds
Shut off fuel pump
e Minimum pressure after 10 minutes should be
2.6 bar (38 PSI). If pressure is too low check:
External leaks
Pressure regulator
Fuel pump check valve
Sensor plate adjustment
Remove fuel pressure gauge and reconnect
fuel lines
e Check for leaks
NOTE: On Golf and Jetta, if hot start problem
persists with residual pressure OK,
replace check valve in fuel pump
reservoir. See repair manual group 20.
COLD ACCELERATION ENRICHMENT
¢ Engine coolant temperature sensor wiring
connector remains disconnected
e Remove intake air boot
e Turn ignition on
e Quickly lift sensor plate fully
Differential pressure regulator should briefly
increase, then return back to previous value
of 80-110mA
e |f reading is not within specifications, check
potentiometer operation page 48, and
potentiometer wiring
e |f wiring and operation are OK, replace
control unit
AFTER START ENRICHMENT
* Engine coolant temperature sensor wiring
connector remains disconnected
e Ground terminal 4 of ignition coil
e Activate starter for 3 seconds then leave
ignition turned ON
Differential pressure regulator current should
increase to greater than 120 mA for between
20 and 50 seconds, then decrease to
maximum warm-up value (80-110 mA)
¢ If not within specifications, check for starter
signal at control unit
e |f signal is OK, replace control unit
FULL THROTTLE ENRICHMENT (QUANTUM 5 CYLINDER, GTI AND GLI)
e Connect 1 side of tool 1490 to temperature
sensor wiring connecter. 15K (1) side remains
disconnected
e Disconnect oxygen sensor
* Start engine and accelerate to above
4000 RPM.
Note differential pressure regulator current
e Close full throttle switch by hand
Differential pressure regulator current should
increase approximately 4 mA.
* If not within specifications check continuity
of full throttle switch and wiring to control unit
e If OK check for speed signal at control unit
e If OK replace control unit
OXYGEN SENSOR CONTROL (ALL 4 CYLINDER ENGINES)
* Bridge engine coolant temperature sensor
wiring connector with [1 side of tool 1490
15k0 side remains disconnected
* Disconnect oxygen sensor
¢ Turn ignition on
Differential pressure regulator current should
be 9 to 11 mA
e Ground male terminal (green lead) of
oxygen sensor
Differential pressure regulator current should
be 19 to 22 mA after 20 seconds
o If not within specifications, check wiring
from control unit to oxygen sensor
e |fwiring is OK, replace control unit
40
41
SYSTEM OPERATIONAL CHECKS
- SYSTEM OPERATIONAL CHECKS
OXYGEN SENSOR CONTROL (QUANTUM 5 CYLINDER ONLY)
e Bridge engine coolant temperature sensor
wiring connector with [1 side of tool 1490
(15K) side remains disconnected)
¢ Disconnect oxygen sensor
* Turn ignition on
Differential pressure regulator current should
coincide with graph in relation to surrounding
altitude
* Ground male lead (green wire) to oxygen
sensor
Differential pressure regulator current should
increase 10 mA from previous reading within
20 seconds
* Remove ground connection for oxygen
sensor and wait 10 seconds for differential
pressure regulator current to stabilize
16mA
Differential
pressure
regulator
current
8mA
4mA
1000 0
1000 2000 3000 4000
Below (feet) ———— Jun _AMbove
sea level
sea level
DECELERATION FUEL SHUT-OFF (QUANTUM 5 CYLINDER, GTI AND GLI)
* Start engine and raise speed above 2000
RPM (Engine must be at operating
temperature)
e Release throttle
Differential pressure regulator current should
briefly go to a negative value (-30 mA to -60mA)
mA)
e |f not within specifications, check idle
switch signal at control unit
e If signal is OK, replace control unit
ALTITUDE SENSOR CHECKING
(QUANTUM 5 CYLINDER ONLY)
Perform if differential pressure regulator is
incorrect based on altitude during test
Remove wiring connector from differential
pressure regulator
Connect adaptor VW 1315 A/1 and multimeter
US 1119 between differential pressure
regulator and wiring connector
Altitude
Sensor wiring
conhector
Set multimeter to 200mA scale
Remove fuel pump relay and install
US4480/3 in its place
. . 1 Signal
Remove wiring connector from altitude ©
sensor 2 (+) Power
« 3(-) Ground
Altitude sensor is located near electronic
control unit
Turn ignition on
Differential pressure reguiator current should
be 10 + 2 mA
Connect.jumper wire between terminals 1
and 2 on sensor plug
Differential pressure regulator current reads
approximately 11-14 mA
Disconnect jumper wire
Heconnect jumper between terminals 1 and 3
Differential pressure regulator current reads
approximately 0-4 mA
If readings are OK, replace altitude sensor
and adjust CO
If readings are not OK, check wiring to control
unit
If wiring is OK, replace control unit
42
43
SENSOR PLATE CHECKING and ADJUSTING
SENSOR PLATE CHECKING and ADJUSTING
SENSOR PLATE HEIGHT
e Run the fuel pump for a few seconds to
build up system pressure
1.9 + 0.15 mm
¢ Remove rubber connecting boot from the air
sensor housing
* Check position of sensor plate
Upper edge of sensor plate must be 1.9 +
0.15mm below the cone edge of the air
venturi on the side closest to the fuel
distributor
<< | To Adjust:
e Lift sensor plate fully
* Adjust position of sensor plate by bending
wire clip
Be careful not to scratch the venturi of the
air flow sensor
a Do not bend the leaf spring
Wire clip
SENSOR PLATE CLEARANCE
* Lift sensor plate until even resistance is felt ® If OK, continue with sensor plate/control
Minimum — noticeable clearance plunger movement checks, page 45
Maximum — 1.9 + 0.15 mm (sensor plate e If not OK perform sensor plate lever basic
even with edge of cone) adjustment, page 45
7
hy y 7 \
т ее
Ш
т
tedster abbey
А
SENSOR PLATE/CONTROL PLUNGER MOVEMENT
Both the air sensor plate and the control
plunger must move freely to insure accurate
control of the air fuel mixture. Clean any oil
residue from the air sensor plate. (Qil residue
can cause the plate to bind.)
Energize fuel pump for 5 seconds to build
up residual pressure then turn pump off
Using pliers or a magnet, lift sensor plate
through entire range of lever and control
plunger travel. An even resistance must be
felt
If the plate binds, check the centering of the
sensor plate and sensor lever on page 47.
If OK, replace fuel distributor
SENSOR PLATE LEVER BASIC ADJUSTMENT
Л
The following adjustment must be made
whenever the air sensor housing or the fuel
distributor is replaced.
With fuel distributor removed check distance
between seating pads of removed fuel
distributor on the air flow sensor and the
roller on the sensor plate lever
Distance should be 19.0 +0.1mm (.748 +
‚004”)
44
45
SENSOR PLATE CHECKING AND ADJUSTING (cont'd)
e |[f measurement is incorrect, adjust CO%
adjusting screw to obtain correct
specification
* Reinstall fuel distributor
* Recheck sensor plate clearance
e |f OK, readjust idle speed and CO%
e {f not OK, remove fuel distributor and adjust
sensor plate clearance with stop screw of
control plunger
Clockwise will increase clearance
Counterclockwise will decrease clearance
Ya turn changes sensor plate position
approximately 1.3 mm (.050”)
¢ Reinstall fuel distributor and check sensor
plate height
¢ Readjust idle speed and CO%
( Increase )
Decrease )
SENSOR PLATE CHECKING AND ADJUSTING
SENSOR LEVER/SENSOR PLATE CENTERING
The sensor plate must be centered in the air
cone. The edges must not touch the sides of
the air cone or free movement of the plate will
be restricted.
TO CENTER THE SENSOR PLATE
* Remove the 10 mm adjusting bolt from the
center of the plate
e Coat the bolt with loctite
e Re-install the bolt (finger-tight)
* With centering too! U.S. 1109 ora .10 mm
(0.004”) feeler gauge, carefully center the
plate Right Wrong
* Torque the adjusting boff to 5-7 Nm (4
ft/lbs.)
* |f plate cannot be centered and lever
appears to be off center in air cone, remove
air sensor housing
TO CENTER THE SENSOR LEVER
¢ Remove clamping bolt on sensor lever
counter-weight
* Coat the bolt with loctite
* Re-install the bolt (finger-tight)
e Slide lever to center position
e Tighten clamping bolt
46
47
SENSOR PLATE POTENTIOMETER
VW 1501
| 14 = 3
| 17 = 2
В 18 = 1
Potentiometer
Terminal Designations
CHECKING
e Remove rubber boot from air sensor housing
NOTE: Before checking the potentiometer, be
sure that the sensor plate is adjusted to
1.9 + 0.15 mm below the edge of the air
sensor housing
e Remove wiring connector from sensor plate
potentiometer
e Connect adaptor VW 1501 to potentiometer —
wiring connector remains disconnected
e Connect multimeter US1119 to adaptor VW
1501 and check resistance value of
potentiometer
Between terminals 1 and 2, reading is greater
than 4K ohms
Between terminals 2 and 3, reading is less
than 1K ohms
e Lift sensor plate evenly
Resistance between terminals 2 and 3
increases up to 4K ohms as plate is lifted
e |f any readings are out of specifications,
replace potentiometer
NOTE: The potentiometer is factory adjusted
and retaining screws are sealed. If
replacement is necessary, continue
with adjusting procedure.
ADJUSTING
e Lift sensor plate with VW 1348/1 until it is
even with the cone edge of the sensor plate
housing air venturi
e Install potentiometer and tighten screws just
enough to hold it in position
e Connect adapter VW 1501 between
potentiometer and wiring connector
e Connect multimeter US 1119 between
terminal 2 and ground
Set to 20 VDC scale
e Turn ignition on
¢ Adjust potentiometer
Voltage read 0.2 to 0.3 volts
e Lift sensor plate fully
Voltage reads approximately 7.0 volts
e Turn ignition off
e Tighten potentiometer screws and seal with
sealing compound or paint
VW 1348/1
SENSOR PLATE POTENTIOMETER
48
49
COLD START VALVE and THERMO-TIME SWITCH
THERMO-TIME SWITCH CHECKING
Since the thermo-time switch contact points are
designed to open 30°C (86°F) for 4 cylinder
engines and 10°C (50°F) for 5 cylinder engines,
perform this check only when the thermo-time
switch is below the specified value.
* Remove wiring connector from cold start
valve
e Ground terminal 4 of ignition coil
e Bridge wiring connector terminals with a test
light
e Operate starter
Test light should glow for approximately 1 to 8
seconds and then go out
COLD START VALVE CHECKING
* Remove cold start valve from intake
manifold (leave fuel line connected)
* Remove fuel pump relay and energize fuel
pump with US4480/3
* Connect jumper wire from one terminal of
cold start valve to + post of battery
* Hold valve in container
* Connect second jumper wire for the other
terminal of cold start valve to ground
Cold start valve should spray in a steady cone
shaped pattern
* Disconnect jumper wires
Cold start valve should not drip within one
minute
* Coolant temperature below 30° C (80° F)
AUXILIARY AIR REGULATOR
CHECKING
COLD ENGINE
Remove wiring connector from auxiliary air
regulator
Start engine and run at idle speed
Pinch either hose connected to auxiliary air \_ 74
regulator | © y
) AM
Idle speed should decrease slightly
WARM ENGINE +
Wiring connector for auxilliary air regulator
connected
Start engine and run until it reaches
operating temperature
Pinch either hose connected to auxiliary air
regulator
Idle speed should not change
VOLTAGE SUPPLY
Remove wiring connector from auxiliary air
regulator
Bridge terminals with test light
If test light glows with engine idling, REPLACE
auxiliary air regulator
If test light does not glow with engine idling,
see wiring diagram in repair manual
50
91
BASIC THROTTLE VALVE POSITION
ADJUSTING
Throttle stop screw
Throttle stop screw is set during manufacture
and should not be moved. If screw position
has been altered, proceed with basic
adjustment.
* Turn throttle stop screw counterclockwise
until a gap appears between the stop and the
adjustment screw
o Turn throttle stop screw clockwise until it
touches the stop
* Turn throttle stop screw clockwise an
additional 1/2 turn
e Check idle speed and differential pressure
regulator current reading
e Readjust idle speed if necessary
FUEL PUMP DELIVERY/INJECTOR BENCH TESTING
FUEL PUMP DELIVERY RATE CHECKING
e Disconnect fuel return line at fuel distributor
Place return line in one quart capacity
measuring container
Remove fuel pump relay and install
US 4480/3
Operate pump for exactly 30 seconds
* Delivery quantity should correspond to the
graph
If fuel pump delivery is incorrect check:
Fuel line leaks
Blocked fuel lines
Blocked fuel filter “e
Blocked fuel tank screen
Voltage at fuel pump with pump operating
If everything else is OK:
* Replace fuel pump
FUEL INJECTORS
Check injector opening pressure and
injector leakage:
* Fill bench tester with mineral spirits (Caution —
mineral spirits are flammable)
* Connect injector to tester
* Open pressure valve and bleed injector by
repeatedly operating tester pump lever
* Measure opening pressure
3.8 to 4.4 bar (55 to 64 PSI)
At 0.5 bar below measured opening
pressure — injector should not drip within
15 seconds
* Replace injectors which fail either test.
* Flush new injectors with tester before
installing
Voltage Available at Fuel Pump
760
675
590
505
420
335
12
Volume
in cc's
52
53
FUEL QUANTITY
Adjusting
Screw
Ms
=
Ar
LN
Пета ОВ ав Ее
CHECKING
shorn
YY A Ta BE -
LS
US 4480
Both the fuel distributor and injectors should
supply the same amount of fuel to each
engine cylinder. Unequal fuel quantity from
either the injectors or the fuel distributor can
cause unsatisfactory engine performance.
* Remove injectors from cylinder head,
leaving fuel lines connected
* Check injector seals for damage and
replace any that are defective
e Check tightness of injector inserts with 12
mm allen wrench
e if loose
Remove insert and clean threads
Apply loctite to threads, reinstall and torque
to 22 Nm (16 ft. Ibs.)
e Remove rubber connector boot from air
sensor housing
* Check for correct sensor plate positioning
* Remove fuel pump relay and install
US 4480/3 in its place
e Place injectors in US 4480. Insure that
fuel lines are not kinked. It may be
necessary to loosen fuel line retaining
clamp to properly position lines in tester
¢ install VW 1348/1 on air sensor
* Turn adjusting screw on VW 1348/1 until
magnet just contacts the bolt on the sensor
plate
* Energize fuel pump
Turn adjusting screw on VW 1348/1
counterclockwise until at least one injector
just begins to spray
* Turn off fuel pump and empty US 4480
FUEL QUANTITY
IDLE TEST
e Lift sleeve of VW 1348/1 to first stop,
simulating idle
* Allow fuel pump to run until! the fuel leve! in
any of the cylinders of US 4480 reaches 20 mi
* Note injection spray pattern
Must be even and cone shaped
All injectors should have the same pattern
* Shut off fuel pump
* Difference between highest and lowest
cylinders
3 ml} or less
e Empty US 4480 #
FULL THROTTLE TEST
* Lift sleeve on VW 1348/1 to last stop,
simulating full throttle
e Run fuel pump until any of the cylinders of
US 4480 is filled to 80 ml
* Note injector spray pattern
Must be even and cone shaped
All injectors should have the same spray
pattern
* Shut off fuel pump
* Difference between highest and lowest
cylinders
8 mi or less
If difference between the volume is
excessive in either test
Interchange the injectors on the two fuel
lines with the widest variation
Repeat volume test
If the same fuel line shows low volume on
the second test, the fue! line is pinched or
the fuel distributor is defective
If the same injector shows the low volume
on the second test, that injector is defective
54
55
IDLE AIR STABILIZATION SYSTEM
CHECKING QUANTUM 5 CYLINDER, GTI AND GLI
Siemens 451 or VW 1367
* Connect engine tester to test plug using
adaptor US1112 and set tester to 4 cylinder
scale
NOTE: Only connect the (+) and (—) and
(dwell) leads of VW 1367 or
Siemens 451. If other test leads are
connected the “duty cycle’ readings
will be inaccurate.
* Ground terminal 4 of ignition coil
= e Disconnect wiring connector from engine
coolant temperature sensor and leave
0000900] disconnected
e Operate starter for about 3 seconds
a Dwell reading should be about 60% (54°)
during cranking
e Connect [1 side of tool 1490 adaptor to
engine coolant temperature sensor wiring
connector
¢ Reconnect terminal 4 of ignition coil
* Start engine and raise engine speed slightly
(To open idle switch)
Dwell reading shouid be about 32% (29°)
e Return engine to idle speed
o Turn on air conditioning
With A/C compressor engaged idle speed
should be 900 + 20 RPM
ore < e |fnot within specifications, check engine
Connector mechanical condition and check for vacuum
Za leaks
— e
e If OK, check wiring for idle air stabilization
b ® | system
6 — e If wiring is OK, replace control unit and
retest
e If not OK, replace idle air stabilization valve
ELECTRICAL TESTING
The entire fuel injection electrical system can
be tested from the disconnected control unit
plug.
Before disconnecting multi-point connector
of control unit check:
Ground connection on cold start valve
Resistance value of differential pressure
regulator
Potentiometer resistance values
Temperature sensor resistance value
Disconnect multi-point connector from
control unit. Wiring conpectors on all
electrical components must be connected
Caution— Disconnect and connect control
unit multi-point connector only with ignition off.
Perform electrical tests in order shown on
trouble shooting procedure sheet using test
leads with flat ends only! Anything else
could damage the multi-point connections
Test Leads can be made locally using
the following materials:
1. 2 flat maie plugs N 17.457.2
2. 2 super flexible leads, each approx. 60 cm long
3. 2insulated alligator clips
of
ELECTRICAL TESTING
ELECTRICAL TESTING
ALL VEHICLES
Terminal # Procedure Result Item Tested
1 +2 Turn ignition ON Battery voltage Fuse
Power supply to terminal 1
Ground connection at
terminal 2
24 + 2 Ground terminal 4 Cranking voltage Starter signal to terminal 24
of ignition coil and (min. 8v) of control unit from starter
activate starter terminal 15A
7 +2 ” ohms Oxygen sensor shield
8+2 Disconnect oxygen 0 ohms Wire to oxygen sensor
sensor wire and
ground green lead
10 + 12 17 to 22 ohms Differential pressure
regulator
17 + 18 greater than 4 Kohms Sensor plate potentiometer
14 + 17 greater than 1 K ohms Sensor plate potentiometer
14 + 17 Lift sensor plate greater than 4 K ohms Sensor plate potentiometer
21 + 2 Resistance corresponds Temperature sensor
to curve, See page 23.
0 (32°F) = 6.0 K ohm
20 (68°F) = 2.5 K ohm
80 (176°F) = 300 $ ohm
1
2
AXE
3
8 9 10 11 12 13
AO
14 15 16 17 18 19 20 21 22 23 24 25
Control unit plug
4 5 6 7
EIA
ADDITIONAL TESTS FOR QUANTUM 5 CYLINDER, GTI AND GLI
Terminal # Procedure Result Item Tested
13 + 2 Ignition ON Battery voltage Idle switch
Idle switch closed
5 + 2 Ignition ON Battery voltage Full throttle switch
Full throttle switch
closed
25 +2 Crank engine 4 to 8 volts Engine speed signal from
ignition control unit
20 +2 0 ohms Ground connection at
terminal 20
3+4 24 to 30 ohms Idle air stabilization valve
1+ 4 12 to 15 ohms Idle air stabilization valve
1+3 + 12 to 15 ohms idle air stabilization valve
16 +2 Ignition ON Battery voltage Signal from A/C switch
A/C switch ON
Compressor engaged
19 + 2 Ignition ON Battery voltage Signal from
A/C switch ON A/C compressor
Compressor engaged
58
99
FUNCTIONAL DIAGRAM FUNCTIONAL DIAGRAM
ALL 4 CYLINDER ENGINES EXCEPT GTI AND GLI GTI AND GLI
30 —e 30-e
15 o > 15 e +
X
X
31
31
A Я
A use mM S10 | А S18
RELAY 25A PANEL
I S10 PANEL I 518 y NE y
ur Na
Engin |
O Starter motor terminal *15a/50 Fuel pump signal trom Conition Starter motor T =
relay control unit
Starter motor terminal #50 = Cold start
15 valve
tg ay Ma
Cold start
a
Fuel pump valve г La Thermo/time
30 31 = switch
Te > Thermo/time
3 e switch
a Ignition control, 7
unit termina .
fc)e Fuel Pumps — o E
or a | compressor
a) 1 24 A A
> 10 24 19 16b—
Control dı3
unit
Fuel pump(s} » й Control 10 D—
ds unit
(My 10 12 21 2 14 17 18 12 Differential
UD О 6 ? 4 3 20 2 21 87 14 17 18 pressure
Т Idle UU Oo v Uv regulator
switch
|
3 |
— | ca YO
1 "NI
=C ||
+ IL
2 || 1
———© | Cm
“e | | +
= Full throttle © Г | | ‘
- switch bb нь NI
fala
y Air sensor ml Idle stabilizer A mn 3 —
Auxiliary potentiometer test connection | | Ai
ir sensor
regulator l Po LY gnition coil potentiometer
A | | ılı terminal #15
Engine coolant Idle air Engine coolant
Oxygen LJ temperature stabilization temperature —
sensor В Sensor valve sensor ]
N Oxygen
Differential sensor
pressure
regulator
| a. d O 0 o
61
FUNCTIONAL DIAGRAM
GLOSSARY OF TERMS
QUANTUM 5 CYLINDER
15 Ÿ
31
S10
Th
FUSE/
RELAY 518
25A PANEL
ый
==>
— h—U¡ |
Engine speed Signal from
Fuel pump signal from ignition starter motor T #50
relay control unit Cold star
old star
30) valve
1
1х
es Thermoftime
- ll = Switc
boa | Ce]
87
> Signal
trom A/C
compressor
Fuel pump motor T#15A/50
|
Signal from o
A
un
Differential
18P — pressure
11 14 17 regulator
v U re
Ca
+
sa
=
a
=
| =
a
с
AN
4 o
=CE M
Cd
on
qn
œ
=)
=
ca
Air sensor
potentiometer
I
|!
i
i
i
ih
IL
i
if
и
HI 3
Full throttle А^ | | | я
switch
в Idie stabilizer A ) | 1 +
test connection | | C
IT Altitude
If) Sensor
11
Idle air ih
stabilization / | |
valve |
i
|}
Engine coolant
temperature
sensor
Oxygen Le
sensor
Il 8 0) £1
24 19 16
10 |
AIR SENSOR — An air cone with a floating plate which measures air flow and determines
control plunger position.
AUXILIARY AIR REGULATOR — A rotary-gate valve which stabilizes idle speed during
engine warm-up.
BAR — Unit of measurement for fuel pressure — 1 bar is about 14.5 PSI.
COLD START VALVE — A solenoid valve for fuel enrichment during cold starts.
CONTROL PLUNGER — A single piston valve in the fuel distributor which controls fuel flow
to the injectors.
COOLANT TEMPERATURE SENSOR — A sensor for measuring engine coolant
temperature to determine cold running engine operation.
DIFFERENTIAL PRESSURE — The difference in pressure between the upper and lower
chambers of the fuel distributor.
DIFFERENTIAL PRESSURE REGULATOR — An electronically controlled valve (actuator)
which regulates fuel flow to the lower chamber of the fuel distributor.
FUEL ACCUMULATOR — Diaphragm unit which helps maintain residual fuel pressure for
good hot starting.
FUEL FILTER — A filter which removes foreign particles from the fuel system.
FUEL PUMP — An electric pump which delivers fuel to the fuel distributor.
IDLE AIR STABILIZATION VALVE — Electronically controlled valve used to maintain idle
speed at a pre-determined level.
INJECTOR — A pressure-activated vaive which directs a cone shaped mist of fuel into the
intake port near each intake valve.
OXYGEN SENSOR — Device used to detect the amount of oxygen in the exhaust gases.
PRESSURE REGULATOR — A diaphragm type regulator used to maintain system pressure
at a given value.
POTENTIOMETER — A variable resistor connected to the air flow sensor that provides a
signal for determining fuel system enrichment.
RESIDUAL PRESSURE — Pressure remaining in the fuel system after the engine has been
shut off.
SENSOR PLATE — A round plate bolted to the air sensor lever which floats in the stream of
intake air.
SYSTEM PRESSURE — Fuel pressure in the fuel distributor controlled by the pressure
regulator.
62
63
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