Author Topic: BPY FSI P2177 CEL - Boost leak - Vacuum Leak - Bad Economy Etc  (Read 6379 times)

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superchicken

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superchicken

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The sawtooth profile on the second chart is what's been driving me crazy.
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83RedRoc

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your IAT sensor?

superchicken

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Pulled the maf and no change in performance, still oscillates. Eventually the car went into reduced performance mode (not necessarily limp).   Iím leaning towards DV or wastehate or N75.  I should really put it on a dyno.
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superchicken

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OK, I did a boost leak test this afternoon by hooking up a schraeder valve to the turbo inlet directly and removed the oil cap as to not pressurize the crankcase.  I started with 5 PSI, no obvious hissing noises.  Upped it to 20 PSI, still no hissing noises.  Looks like mechanically the car doesn't have any leaks. 

I did hear a gurgling noise coming from inside the valvecover which I suspect would be air pushing past the turbo bearing seals into the return pipe and bubbling back up in the bottom of the pan... but I figure that when the engine has oil pressure those bearings would be sealed up.

So - it's gotta be electrical.  I still get an obvious oscillation at part-throttle climbing hills, like the car is rubber-banding, and the fuel economy is terrible.  The car makes good power, just drive ability is a bit suspect.

I need to re-log the car to get some fresh data.

Would removing the cat and staying with stock software have an impact?  Is the car stuck in cat pre-heat mode?
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superchicken

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Replaced the D revision DV with the original rubber pierburg unit, (no rips).  Doesn't seem to have made a difference aside from now you can hear compressor flutter on throttle lift.

Would a failed N75 be common?
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83RedRoc

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fairly its just a  frequency valve.   

If you unplug the rear 02 it won't affect driving,  it'll just have a CEL for short to - on the 02.

You can log 118 and see the duty cycle % of the N75.