Hey guys

Normally boosts strongly to 14-15psi, albeit a bit of a laggy start. Now though, it boosts rubbishly to 7psi and stays there, solid as a rock. Now you can all imagine how rubbish it is, and sounds. I thought initially it may have been fuel (live in broome, only got premium) but have been running the same crud the whole time. Have stock ecu, but minor mods like s/s 3" exhaust, BOV etc. I think it could posibly have somethign to do with the AFM, or even the BOV. I have a feeling it may be causing the boost leak.

Any help would be appreciated, cos i would like to sell it soon, but wont do when someone can buy an equally as fast excel for the same money...

BTW it is a 94 GC8 with fresh rebuild with STI bottom end

Sounds like you have lost your Electronic Boost Control and its running of the Wastegate Actuator manual default setting. Check the wiring to your EBC valve. Then check the EBC air bleed line is not blocked. This runs from the EBC valve to the Post turbo Intake hose.

If you can find the procedure you can run a diagnostic on the EBC valve by utilising the reset / test connectors and hear if it pulses when cycled.

i am currently having a similar issue, however, mine is random. the car can work fine for over an hour and then not boost for an hour, or work for 10mins and not boost for 10mins and run fine again - totally random. i thought i had fixed it with replacing and tightening bov hoses, checking for vac leaks etc.

what it could be... excess lifter noise is triggering the knock sensor and the timing is being retarded. at least that means the knock sensor is working, to solve it - tomorrow i will purchase and use a bottle on Nulon Lifter Free-up. This stuff says it may take up to 14 days to work - fingers crossed it'll solve it a bit quicker than that.

but check for boost leaks first.

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Did you unplug the pressure lines that go from the turbo to the wastegate? On my 01 there is a t intersection with a bead in one of the hoses and if its on the wrong way it will only boost to .5bar. Hope this helps...