Ever since replacing the FIAV gasket, ISC, and ECU (yes thay were all related /ubbthreads/images/graemlins/frown.gif), I've had idle surge. After boost leak testing, I found a leak at the throttle body shaft seals, and near the turbo. I replaced those with WORKS seals, and fixed it. I also cleaned the TB blade of deposits by removing it. It's shiny clean /ubbthreads/images/graemlins/smile.gif. A friend hosed it down with brake cleaner and scrubbed it, hence the seal failure. Dang friends. Anyway, after doing the seals, the idle is around 3000 RPM.
I re-adjusted the TPS as per VFAQ, and set it within spec. The resistance curve was smooth. I then attempted to set the BISS as per the VFAQ. Even with the proper pins grounded and the screw turned all the way down, I still have idle above 2000 RPM. I am guessing that there is still a large leak somewheres along the intake tract, so I hook up the boost leak tester again. Pressure drops quickly, about 1 PSI every 2 seconds. The leak from the turbo area remains. Spraying it down as best I can with soap water, I can't find the leak.
When I took the accordion hose off, I saw engine oil pooled in the turbo inlet. The PCV system is still installed. Bad shaft seals perhaps, or just the PCV? Could a bad shaft seal be allowing air into the oiling system and be the source of this latest boost leak? I would think it wouldn't be enough to cause such a large idle increase, but I really don't know. I don't hear any other leaks from the intake tract, but it's possible the large leak is making them difficult to hear.
Edit - I'd like to add that the compressor shaft has no side to side or in and out play that I can discern. Just stick your fingers in an wiggle it right? /ubbthreads/images/graemlins/smirk.gif
I re-adjusted the TPS as per VFAQ, and set it within spec. The resistance curve was smooth. I then attempted to set the BISS as per the VFAQ. Even with the proper pins grounded and the screw turned all the way down, I still have idle above 2000 RPM. I am guessing that there is still a large leak somewheres along the intake tract, so I hook up the boost leak tester again. Pressure drops quickly, about 1 PSI every 2 seconds. The leak from the turbo area remains. Spraying it down as best I can with soap water, I can't find the leak.
When I took the accordion hose off, I saw engine oil pooled in the turbo inlet. The PCV system is still installed. Bad shaft seals perhaps, or just the PCV? Could a bad shaft seal be allowing air into the oiling system and be the source of this latest boost leak? I would think it wouldn't be enough to cause such a large idle increase, but I really don't know. I don't hear any other leaks from the intake tract, but it's possible the large leak is making them difficult to hear.
Edit - I'd like to add that the compressor shaft has no side to side or in and out play that I can discern. Just stick your fingers in an wiggle it right? /ubbthreads/images/graemlins/smirk.gif
Last edited by a moderator: