GFB G-Force2 - Manual (Page 15)

Boost pressure remains the same regardless of the duty cycle setting:
Turn the ignition off, then on again and listen for the solenoid to click rapidly for about 1 second. If you can’t hear it click
on power up, check the wiring loom to the solenoid valve.
If the solenoid does click rapidly on power up, check the hose connections to the solenoid valve and wastegate - make
sure the un-used solenoid valve port is not plugged, and that the boost pressure and wastegate hoses are connected to
the right ports.
Check the controller is receiving full battery voltage. If it is powered off a low voltage supply, the display will work but the
solenoid will not.
The peak boost pressure always seems to be higher than the target that was originally set:
The car may not have been driven in a way that achieved the “true” peak boost whilst duty cycle was being set up. Go
back into Duty Cycle and either reduce the duty cycle value so that peak boost comes down to where you want it, or
leave the duty cycle alone and drive the car again to learn the “true’ peak boost.
Boost pressure spikes (overshoots the target):
Reduce the Gain setting
Boost spiking should not be confused with boost taper (see
below). Boost taper often looks similar to spiking in low gears
because the RPM increases so quickly.
Boost pressure oscillates significantly:
Reduce the Sensitivity setting
If the closed-loop taper correction is set too high, the boost may
fluctuate rapidly up and down, which is a sign that the system is
going “unstable”. It means the correction is too strong, and whilst a
weaker setting will eliminate the instability, boost will likely still
drop off a little because the turbo is nearing its limits (see boost
taper below).
Boost tapers off even with a high Sensitivity setting
This is a sign that the turbo system is operating beyond its efficient
limits. Either the turbo is too small to hold high boost to redline, or
the wastegate spring is too soft. If you are using a duty cycle of
more than 70%, it’s possible that a stronger wastegate spring and
lower duty cycle will hold a more stable boost pressure.
Boost pressure starts to increase significantly at high RPM:
This is called boost creep, which is a result of the wastegate not
being large enough. It may hold boost stable for some of the rev
range, but at high RPM it is wide open and not flowing enough to
prevent boost from rising further. At this point the G-Force II can do
no more, the only solution is a larger wastegate.
Troubleshooting
15 - Additional info
RPM
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RPM
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RPM
B
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RPM
B
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