Disconnect TPS, whats supposed to happen? Boost problems still

[MikeWasHere05]

See http://www.audizine.com/forum/showthread.php?t=219276 for history of problem.


New N75 doesn't solve problem. Car broke down again, replaced the new MAF with the old MAF (again) and car is running at 14 psi (again).

Disconnected the TPS to see if it would run. On my friends VR he uses this method to diagnose the MAF. He says if the car doesn't run, the MAF is faulty. Is this applicable to our cars? For reference... my car didn't run.

So I also logged block 002, at full throttle on my PC-16 setup I received 160 g/s. I believe this is correct, could someone confirm it for me please.

Thanks
mike

[20vpower]

my logs show ~186 g/s for my maf at 6600 probally about ~70ish degress (it was a 10pm and its been hot lately)

[MikeWasHere05]

Just gonna go over everything again, in full. If you can provide any support I'd be in a whole lot of debt to you, as I've been trying to figure this out for weeks now.

Car is a 1998 A4 1.8T (AEB) with a K04, fmic and PC-16 setup. When running good the car spiked 21psi and held 17-18.

2.5 month ago - Spark plug failure @ Show n' Go. Bent a few valves, had to rebuild head. Initially thought I had a failed MAF, put new MAF in and just put the old MAF in the basement.
1 month ago - Car doesn't start, MAF signal too low code. Put in old MAF and car runs ok, but now only boosts ~5psi. Tighten some hose clamps and car now holds 14psi. Car runs a little rich I believe, definite loss of power. Boost onset is very weak.
2 weeks ago - In effort to solve boost issue, replace original MAF with new MAF from Audi (a replacement to the failed new MAF). Car still runs bad. Accidentally tear TIP.
1 week ago - APR TIP installed.
Today - New N75. Drive the car up the street and it craps out on me again. Roll it back down the hill (thank god I live on a hill), replace the MAF and it runs ok again. However, still only boosting 14psi.

So a list of what I've done:
- After going through 2 new MAFs, original MAF is in the car. Reads 160g/s at full throttle.
- Replaced N75C valve.
- Checked for boost leaks, system is sealed.
- Tried running car with no MAF, runs like crap. Tried running car with no TPS, doesn't run.
- Disconnected line from N75 to wastegate, still doesn't hit above 14psi.

I'm coming to the conclusion that its something with the turbo... . Does anyone have any other suggestions to diagnose this, or any good turbo shops that I can ship the K04 to and have checked out?

[20vpower]

what if you hooked up the n75 lines wrong? would that have anything to do with it? just throwing it out there

[MikeWasHere05]

my logs show ~186 g/s for my maf at 6600 probally about ~70ish degress (it was a 10pm and its been hot lately)

hmm...

Well I guess I'm going back to Audi to get another new MAF. This is the second new MAF to blow on me, which confuses the crap out of me. It can't be the wiring or anything since the old MAF has yet to actually not work. I think I'm gonna try cleaning the new MAF and if it decides to work I'll log that one.

[MikeWasHere05]

what if you hooked up the n75 lines wrong? would that have anything to do with it? just throwing it out there

Pretty much followed that diagram (minus the MBC). Long side in the TIP, bottom goes to the turbo housing and small side to the wastegate. I believe thats correct...

[MikeWasHere05]

The more I think about it, the more I think that there must be a way to definitively diagnose a bad wastegate.

The N75 takes pressure from the turbo, reduces it according to the ECU's specified duty cycle, bleeds the excess to the TIP and releases the rest to the wastegate actuator. So either the N75 is allowing too much air to the wastegate actuator, opening the wastegate prematurely; or the wastegate is maladjusted and opening at too low of a pressure.

Since I've replaced the N75, it is unlikely that the N75 is the problem. The next item is the wastegate actuator. The way to test this would be to apply the pressure manually (via compressor) and see when the wastegate opens. The problem is I don't know the pressure that it is supposed to open at, and can't find the answer despite days of searching.

However I guess I could have had 3 faulty MAFs. Which wouldn't surprise me, seeing as 2 of them caused the car to not run at all...

[MikeWasHere05]

bump?

[20vpower]

bump get a compressor

[MikeWasHere05]

bump get a compressor

Have the compressor, don't have the wastegate spring pressure numbers