Thank you for purchasing the GFB Deceptor Pro II blow off valve. We highly recommend that you familiarize
yourself with the operation and adjustments of the Deceptor Pro II before installing it.
Installing and wiring the in-car volume controller
CAUTION: Because the two valves supplied in this kit are mirrored, one of the extension looms contains a
signal reverser so that both valves work in unison. It is VERY important that the CORRECT valve is
connected to the reversing loom, or damage could occur. Please pay close attention to the steps below:
1) Plug the wiring “Y” loom into the upper BOV slot in the back of the control box
2) Plug the extension wires together according to the numbers attached to each plug and valve, i.e. connect all
plugs with a number 1 together, and all plugs with a number 2 together
3) Plug the power cable (red and black wires) into the lower slot in the back of the control box
4) Connect the red power wire to the positive terminal of your car’s battery or a 12V source. Connect the black
wire to the negative terminal. Upon initial power-up, the valves will perform an open/close cycle before
reverting to the position indicated on the controller dial. By turning the dial and watching through one of the
valve’s venting outlets, you will see the inner sleeve move to open or close each of the venting ports
alternately, which is how the venting volume is adjusted
5) Once the correct operation is confirmed, disconnect the valves and continue with the control box installation
6) Find a suitable location on or around the dashboard, steering column or instrument binnacle for your in-car
volume controller. Clean both mating surfaces with Methylated Spirits or similar cleaner and secure the
controller using the supplied double-sided tape. Press hard and hold the unit for about 30 seconds, and note
that it takes up to 24 hours for the tape to develop a strong bond
7) Using a multi-meter or voltmeter, find a suitable power wire that reads 12V only when the ignition is turned
on. Solder the end of the volume controller positive (red) wire to the 12V source. It is possible to use a wire
tap or crimp instead, but soldering is the most reliable joint. Make sure to insulate the joint properly
8) Find a suitable bolt on the body/chassis and connect the unit’s ground (black) wire to it
9) Pass the controller’s extension leads through the firewall into the engine bay. Often there is an existing
grommet that can be used for this purpose. In any case, it is important to ensure that the lead is protected
where it passes through the firewall to prevent wear or damage. Now proceed with the valve installation
Using the In-Car Controller
When powered up the volume dial rim will glow red, and will brighten for easy reading when you make an
adjustment, then automatically dim 3 seconds later to reduce unnecessary glare. The position of the dial is directly
proportional the venting bias - turning the dial fully anti-clockwise sets the valve to 100% recirc, fully clockwise
results in 100% atmosphere venting, and any proportion is possible between these limits.
The controller also features a program button on the rear of the casing. This can be used to limit the range of the
atmosphere-venting bias of the Deceptor Pro II. For example, if you prefer that the maximum atmosphere venting bias
is 50%, you can program the controller so that full travel on the dial gives you only 50% movement at the valve. This
is particularly useful on cars that through experimentation, find that full atmosphere venting does not agree with them.
To use this feature, set the dial in a position that you want as your maximum atmosphere-venting limit, then press and
hold the program button until the dial flashes. The unit will now record this position as the maximum atmosphereventing limit. Now when you turn the dial fully clockwise, the Deceptor Pro II will only open as far as the point
which you have just set. For example, if you pushed the button with the dial set in the middle (50% atmosphere
Page 3
venting), full travel of the dial will now move the valve from full recirc to 50% atmosphere-venting only.
Every time the button is pushed, the position of the dial will determine the maximum venting bias of your Deceptor
Pro II. To re-set the controller to allow the full range again, simply turn the dial fully clockwise and hold the button.
Installing the blow-off valves
Make sure to fit the valves on the correct side of the engine bay. The trumpet and servo motor should
point downwards in both cases when installed. If the trumpet and servo point upwards, swap the valves
to the opposite side.
Follow the procedure below on one side, then repeat for the opposite side.
1) Open the clamp and remove both the recirc hose and the vacuum hose from the factory valve
2) Using a 12mm socket or wrench, undo the two bolts and remove the factory valve from the
intercooler pipe – take care not to drop the gasket
3) To make the next step easier,
loosen the hose clamps on either end of
the metal section of intercooler pipe, then
remove or rotate the pipe to gain access
to the flange – it’s a good idea to stuff a
rag into the open end of the intercooler to
prevent anything falling in whilst you
work
4) Screw the short end of the
supplied threaded stud into the lower hole
of the valve mounting flange as shown
opposite. Put the supplied gasket on the
threaded stud
5) Position the Deceptor Pro II onto the flange,
then lift it off the flange just far enough to slip the
supplied nut under the servo motor, then begin screwing
it onto the end of the threaded stud. Just do it up finger
tight at this point.
6) Now thread one of the factory bolts into the
upper hole (making sure the gasket is correctly
positioned in between), then tighten both fasteners fully
7) Re-fit the section of intercooler pipe, and tighten
both hose clamps.
8) Push the recirc and vacuum hoses onto the
Deceptor Pro II, then re-fit both the hose clamps
9) Connect the servo motor plug to the wiring loom
from the controller, and make sure the cable is securely
routed through the engine bay away from exhaust or
turbo parts
10) Repeat on the other side
Page 4
Spring Adjustment
Contrary to popular belief, the spring pre-load DOES NOT need to be adjusted to suit different boost
levels. The valve will stay shut under full throttle conditions regardless of boost pressure or spring preload.
Rather, the spring pre-load affects how easily
the valve opens when you lift the throttle, and
how long it stays open when it vents. Adjusting
the spring is a simple matter of ensuring the
valve opens enough to release the air, but not
long enough to cause idling problems. The guide
below will walk you through the steps involved.
The screw in the centre of the head is the spring
adjuster (shown opposite). Use the supplied
5mm hex key for this screw.
The softest spring setting is achieved when the top of the adjustment screw is 3mm above the head of
the valve. Do not set the screw more than 3mm above the head.
Set the spring to the softest setting, and set the venting bias (via the electronic controller) to at
least 50% atmosphere venting so you can see the piston through the trumpet
Start the car and let it warm up to normal operating temperature. Make sure the A/C is off
Give the engine a good hard rev, and watch the piston - WARNING: Keep your face away from
the trumpet opening when revving the engine. View the piston from an angle away from the blast
of air. The piston should lift a little and vent with a “whoosh”, then close slowly and smoothly.
The harder you stab the throttle, the further the piston will open (note: it will only open fully
when driving, as the turbo does not generate significant boost until the engine is under load).
If the piston stays open too long and does not close before the revs drop back to idle, the engine
will “stumble”. If this happens, wind the adjustment screw in the “+” direction one turn at a time
until the engine returns smoothly to idle after revving
For the final fine-tune, take the car for a drive. Watch the tacho as you pull up to a stop - if the
revs dip below idle and then rise again, tighten the spring another 1-2 turns
If a loud flutter is heard when lifting off sharply after accelerating hard above 3500RPM, wind
the adjustment screw in the “-“ direction one turn at a time until the noise disappears. Note that it
is not uncommon to hear a slight fluttering at low RPM, particularly if you partially spool the
turbo and lift off slowly. This is a result of the different way in which this valve operates
compared to the factory unit- this is normal and not detrimental to the turbo
Technical Support
If you experience any issues during installation or use of your GFB Deceptor Pro II that are not
answered in these instructions, please contact the GFB tech support team on +612 9534 0099, or email
support@gfb.com.au.
This product is intended for racing use only, and it is the owner’s responsibility to be aware of the legalities of fitting t his product in his or
her state/territory regarding noise, emissions and vehicle modifications.
GFB products are engineered for best performance, however incorrect use or modification of factory systems may cause damage to or reduce
the longevity of the engine/drive-train components.
GFB recommends that only qualified motor engineers fit this product. Warranty is for the period of one year from the date of purchase and
is limited only to the repair or replacement of GFB products provided they are used as intended and in accordance with all appropriate
warnings and limitations. No other warranty is expressed or implied.
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