Stratified Guardian Angel User Manual 0204
© Stratified Automotive Controls
Stratified guardian
Electronic Overboost Failsafe WITH
Vent to Atmosphere Valve Control
Installation and User Guide
Thank you and congratulations on the purchase of your new Stratified Guardian
Angel over-boost protection device. This document should be followed to ensure safe
and proper installation and operation of your new device.
© Stratified Automotive Controls
ALL parts are sold for OFF ROAD RACE-ONLY ground vehicle use only.
Aftermarket systems interacting with engine function are not for use on pollution controller vehicles.
Alteration of emission related components constitutes tampering under most local emission regulation
guidelines and can lead to fines and penalties.
Limited Warranty
This Stratified product is warranted against defects in materials and workmanship for ninety (90) days
from date of purchase. During the warranty period, Stratified will repair, or at its option replace at no
charge, components that prove to be defective. The product must be returned, shipping prepaid, to a
Stratified facility. This limited warranty does not apply if the product is damaged by accident or misuse.
The foregoing warranty is in lieu of all other warranties expressed or implied including but not limited
to any implied warranty of merchantability, fitness, or adequacy for any particular purpose or use.
Stratified Automotive Controls LTD. is not responsible for any fines, injuries, or damages incurred as a
result of the installation or use or misuse of our products. It is the complete responsibility of the
purchaser of such products to ensure that they are used in a legal, safe, and appropriate manner.
© Stratified Automotive Controls
Table of Contents
Introduction and Precautions .................................................................................... 4
Quick Install Guide.................................................................................................... 6
Installation Instructions ............................................................................................. 7
Test and Setup ....................................................................................................... 11
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Introduction and Precautions
The Guardian Angel (GA) is an overboost failsafe device that releases the Bypass Valve (BPV)
on turbocharged vehicles if the measured boost pressure exceeds a user-preset value OR the
device is triggered via an external device (such as an engine controller, water-methanol injection
system, etc).
The GA will immediately release excess boost in the event of an overboost or trigger event. This
is a much gentler process than a fuel or ignition cut. It is easier on the drivetrain and allows the
driver to continue driving even in the event that the device is triggered making it safer than an
ECU fuel or ignition cut.
The GA protects against any type of overboost condition, whether it is caused by a poor tune,
boost spike, or even a mechanical failure of the wastegate.
Another feature of the GA is that it allows the use of vent to atmosphere push-type valves to be
run in MAF based vehicles. In MAF based vehicles, releasing a BPV or BOV to atmosphere
causes very rich conditions at idle and during shifts. With this feature enabled (see how to
enable it in the document below), the GA will stop the BPV from leaking at idle and during
shifts allowing you to run the valve in VTA (Vent to Atmosphere) without a loss of driveability.
The GA works with push type BPVs. Most factory and aftermarket BPVs are push type valves.
One way to test if your BPV works with our device is to pull the vacuum line from the valve and
to see if the valve opens under boost. If it DOES our device works with it. The GA DOES NOT
work with pull type or reversed valves. The HKS SSQV and all imitations are pull type valves
and do not work with the GA.
The device works with both re-circulated and vented to atmosphere (VTA) valves. If your car is
MAF/VAF based and the valve is VTA, when the device is triggered it will cause a rich
condition since metered air is now lost to atmosphere instead of being burned along with the
fuel. If the valve is re-circulated, the air fuel ratio commanded by the ECU will be maintained.
When the GA is triggered, the amount of boost pressure released depends on the flow capacity
of your BPV and turbocharger. In normal circumstances this will bring the boost pressure low
enough to avoid damage. However you may see a small boost spike above the trigger point of
the GA. This is normal and just relative to how quickly your BPV is able to vent the extra boost.
The Guardian Angel is a safety device and not meant to be used as a boost controller. Having
the Guardian Angel triggered all the time makes the turbocharger work unnecessarily hard and
may increase wear.
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The Guardian Angel is water repellent but NOT water resistant and should not be mounted
directly on the engine itself. Do not power wash the unit and mount it off the engine - preferably
close to other vehicle electronics such as the fuse box.
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Quick Install Guide
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Installation Instructions
1. Park the vehicle safely and remove the negative battery cable.
2. Find a suitable location where the Guardian Angel (GA) will be mounted. The unit
is rated for under-hood temperatures (up to 125 degrees Celsius), however it
should be placed away from direct heat sources such as the exhaust manifold or
turbocharger. It should also be placed away from water and water drains. A
suitable location is on top of the vehicle's fuse box as shown below:
3. Secure the GA into place using either double sided automotive tape or fasteners
through the flanges of the enclosure.
4. The GA has 3 electrical connections: +12V Power - RED wire, Ground - BLACK
wire, and an external trigger - BLUE wire.
5. Connect the power of the GA (+12V) to a power source using an Add-A-Fuse (not
included) or similar setup. Make sure this power source is always on while the
ignition is in the ON position. Test this circuit to ensure this is the case using a
voltmeter. The GA uses less than 1 Amp of current, so choosing a fuse in the 2
Amp-5 Amp range is appropriate. A sample Add-A-Fuse in a Mazdaspeed3 is
shown below:
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Add-A-Fuse circuit that powers
the Guardian Angel
6. Connect the ground ring terminal to a solid chassis ground as shown below:
GA ground terminal connected
to 10mm chassis ground stud
7. The indicator LED should be brought inside the cabin and placed somewhere
where the driver will see it at all times.
8. The BLUE trigger wire can optionally be wired to a controller or device that can
trigger the GA independently of boost pressure. Such a device can be a watermethanol controller or standalone ECU. The signal the controller needs to send is a
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positive 5Volt or higher. If an external trigger is not used, tape and secure this wire
with the others.
9. Once all electrical connections are secured, plug the electrical harness into the GA.
10. The next step involves connecting your Bypass Valve (BPV) vacuum line to the
GA. One end of this hose is connected to your vehicle's intake manifold and the
other end is connected to the BPV.
11. Locate your BPV and ensure that it works with the GA (This is explained in the
Introduction and Precautions section). Locate and disconnect the vacuum source
from the BPV. This is the smaller vacuum hose located at the top of the valve and
is shown below on a Forge brand BPV.
BPV Vacuum Port
12. Connect and secure this hose to the port called BPV in on the GA. 5/32" or 3/16"
ID hose sizes work best. Work the hose on gently and secure it in place. Don't
force the hose onto the GA's barbs, if it does not fit easily lubricate with some soap
or procure a larger size hose.
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Connect hose from
manifold to BPV IN port
13. Obtain another vacuum hose of similar size (5/32", 3/16" or similar) and connect
this hose from the BPV OUT port of the GA to the vacuum source port of your
Connect hose from BPV
OUT port to BPV
vacuum source
14. Now that all the hardware is connected, it is time to test and setup the unit. These
are very important steps described below.
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Test and Configuration For OVEBOOST Protection
You will notice a turn dial called SETPOINT on the front of the unit labelled 10-40psi.
This sets the boost pressure at which the GA will trigger. The markings on the case are
there as a guideline, so you will have to do a bit of trial and error testing to set the GA at
an appropriate level. DO NOT just rely on the markings on the case.
1. First of all, turn the ignition to the ON position. The LED should light up and stay
on for 2 seconds. This is a self test that happens every time the GA is turned on. It
shows you it is powered. If the LED does not come on when you turn the ignition
on, something is wrong either with the wiring or unit itself.
2. The SETPOINT dial has a very small arrow on it. Locate this and set the
SETPOINT dial to the lowest position (10psi).
3. Take the car for a drive and try to go over 10psi of boost. The GA should trigger,
you should feel a gentle reduction in boost and the LED should come on to tell you
it has triggered. Monitor that your boost is indeed dropping once it triggers.
4. Take your foot off the accelerator and you will see the LED turn off. The GA will
reset once the engine is out of boost.
5. If you are using an external trigger, this is the time to test this as well. Set this
trigger to actuate the GA under boost and watch that the LED comes on and boost
drops. Once again, when the engine is out of boost, the GA will reset. The external
trigger works independently of the boost SETPOINT.
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6. Now it is time to set the GA to a reasonable boost trigger level. Generally you want
the GA set 1-3psi above what boost you normally run and 2-3psi BELOW the
ECU fuel cut.
7. To do this, move the SETPOINT dial up to close to where you expect your boost to
be. Go for a test drive and see if you can trigger the GA at the top of your boost
range. If you triggered it at the top of that range, move the SETPOINT higher by
turning the dial approximately 15 degrees in the clockwise direction. The
adjustment resolution is: for every 10 degrees the dial is turned, the GA trigger is
adjusted by approximately 1 psi.
8. Since the GA is not a device that is used all the time but should always be ready,
we advise that you test your GA periodically. Every couple of months, trigger the
GA and make sure it is lowering your boost as expected.
© Stratified Automotive Controls
Test and Configuration For Vent to Atmosphere
When running a VTA (Vent-To-Atmosphere) BOV or BPV in a vehicle that has a MAF
or VAF sensor, the valve will vent air that has already been "counted" by the sensor. This
causes a very rich condition and bogging and afterfire during shifting.
Furthermore, push type BPV and BOV valves tend to leak at idle or part throttle and
therefore once again create very rich conditions when run in VTA mode. Tightening
down the valve spring to stop them from leaking usually causes turbocharger compressor
surge and it is not desirable.
The GA offers a feature that can be toggled on or off that closes the BPV/BOV at idle
and low throttle preventing leaks. It also makes the valve much more responsive after it
releases to atmosphere so the car will not bog during shifts.
You can toggle this feature ON or OFF by doing the following:
1. Power the GA off by either unplugging the main harness or turning off the supply
of power from the vehicle (turning the ignition key off).
2. Take the BLUE external trigger wire; make sure the copper is exposed on the end;
and hold the copper of the exposed wire against a +12V power source such as the
positive post of your battery as shown below.
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3. While holding the BLUE external trigger wire against the +12V source, power on
the GA by plugging it back in or turning on the key and continue holding the
BLUE wire against +12V for 2 seconds.
4. Now the VTA feature was toggled ON if it was off or OFF if it was on.
5. The VTA feature will remain in this state (either on or off) until steps 1-4 are
repeated. Please note that while the VTA feature is on, you will see the indicator
LED flash twice every time the unit is powered on. You will also notice that the
indicator LED will now turn on while at idle and low load conditions. This is
NORMAL with the VTA feature turned on. This is the GA controlling your
BPV/BOV so it can be run in VTA mode.
6. With the VTA featured turned on, the GA is still protecting you from overboost this is the main function of the GA and overboost protection can't be turned off.
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7. When in boost, the indicator LED will be off if everything is normal and it will
turn ON if an overboost condition occurs.
8. If you find that you hear fluttering or surging while running in VTA mode, use a
softer spring in your BPV/BOV or reduce the tension on the spring. With the GA
controlling your valve in VTA you no longer need a very stiff spring to hold the
valve closed at idle.
© Stratified Automotive Controls
The Guardian Angel is designed to be installed in the engine bay; away from direct
sources of heat and water. Damage caused by exceeding the operating conditions
listed below or exposing the Guardian Angel to water will void the included
Power Supply Max Operating Voltage:
Power Supply Min Operating Voltage:
Maximum Operating Temperature:
Absolute Boost Pressure Trigger
Adjustability Range:
External Trigger Minimum Voltage:
Current Draw in Operation
+16.5 Volt
+11.5 Volt
125 degrees C (257 degrees F)
10-40psi +/- 2psi (70-275Kpa +/14Kpa)
+4.5 Volt
< 0.75 Amp
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