tmmatthews

<center><img src="http://pictureposter.audiworld.com/7651/block_114-tmm.jpg"></center><p>Bear with me, I actually have questions at the end I finally got around to putting a boost gauge in my car, partially because it was down on power. Sure enough, my boost is topping out around 2 psi. I spent the past two weekends trying to track down the source and here is what I have:

- VAG-COM Block 114 shows from 1.55 to 8 ms deviation between Corrected Load and Actual Load as well as a nearly constant 99.6% N75 duty cycle which according to the Bentley points to: N75 valve, N75 wiring, stuck wastegate, boost leak, or malfunctioning turbocharger.
- 2 psi max on the gauge. Vacuum reads normally (20-22" at idle).
- Pressure tested the system and found no leaks, boost gauge read 5 psi when pressurized.
- Pressure gauge reads normally when hooked directly to compressed air source.
- Only DTC is 17965: Charge Pressure Control, Positive Deviation and even that doesn't regularly return when cleared.
- N75 valve functions normally under output test with VAG-COM.
- Wastegate actuating rod moves when compressed air is applied to the diaphragm, as well as when applied through the N75 valve. Rod moves normally when constant pressure is applied during the N75 output test.
- No change in boost when changing between the stock BPV and Hyperboost.
- Compressor wheel spins freely
- No "bad" noises from the turbo

So, it appears that either the wastegate is staying open when the car is running (due to wastegate/diaphragm/N75 problems) or there is an internal problem with the turbo. I'm considering briefly bypassing the N75 valve just to see if it is a wastegate problem.

Am I missing something? Is there a way to tell if the compressor is being spun without major disassembly? Does anyone have any other suggestions? While I would love to just yank out the K03 and replace it with a K04 it is just not practical at this time.

Thanks,

Sourdough Josh

Really sounds more like a turbo problem to me.

Dead

I'd disarm the wastegate and see if it boosts. Just be careful and don't over boost.

Yippers®

I'd bypass the N75 for a test .. just don't whack on the car ...

Dead

That's why I suggested it already. ;-)

Audiboy

to force close the wastegate. This will give you an idea if the wastegate pressure valve is somehow stuck open.

Then, just take off the downpipe and catalytic enough to get a mirror in there and see how the wastegate's looking. I think you are on the right track

Also, how much pressure did you put through the N75 to open the wastegate. It should open max around 6-8 psi.

Yippers®

fools never differ" Which are we ?

Dead

Great mindless fools.