Hi All,
A couple of weeks ago I picked up a '99 S4 Avant (Imola Yellow!). An awesome car and I love to drive it! However, I'm having a problem with it and I was wondering if anybody has run into something similar and could help out...
Using VCDS (VAG-COM) I pulled this error code from the ECU:
17965/P1557/005463 - Charge Pressure Control: Positive Deviation
This is the only code I get. Some googling suggests that this is an overboost problem. Here's what I've checked out so far:
- Checked the Throttle body boot - seems fine, removed and inspected
- Smoke test of intake system - no leaks observed
- VCDS output test of N75 valve - solenoid appears to be working fine (heard clicking)
- Checked the Diverter valves - broken, replaced both with 710N's - code comes back after clearing
- Cleared the codes and logged blocks 115, 118 using VCDS
- Did a few pulls in 4th gear from 2k RPM up
- First couple of pulls indicate correct boost
- Subsequent pulls cap at ~5psi, requested boost at ~11psi, N75 duty cycle constant 10.2% - I think this is limp mode
Took it to German Automotive in the North Shore who couldn't find anything obviously wrong with it to cause this problem. Intake system was smoke tested by them with no obvious results. They also said the Turbo waste gate was actuating correctly which appears to rule out the N75.
They suggested the car might have been chipped/mapped - badly - which is what's causing the codes/limp. Not 100% sure on that because if it was chipped you would see the ECU request > 11psi boost. He gave me the card of Kent from Speed Source and I'm already talking to Dave from NZ Performance Tuning...
So I guess the only thing left to look at is a full pressure test of the intake system or maybe something funky going on with the N75 valve or the waste gate of the turbo.
Is there anybody here that can offer some help or advice? I'm a bit of a noob with this car so all I know is what I've picked up from reading about it. Failing that, can anybody recommend a superstar mechanic or other genius that knows their way around this car and would take a crack at diagnosing the problem?
Thanks for your help all!
Chris.
P.S. I'm happy to share my VCDS & cable with those that need, I'm on Auckland North Shore if anybody needs :)
Hi Chris
Congrats on selecting the best colour!!!
Try searching or posting this on www.audisrs.com. There is a whole lot of experience on the board of the B5 S4/RS4. A quick search seems to point to N75, or possible boost leak.
I would get the system pressure tested.
I would also look for someone with experience with the S4/RS4 as they seem to have their peculiarities.
Quote from: vaudiw on May 10, 2011, 09:48:12 PM
Hi Chris
Congrats on selecting the best colour!!!
Try searching or posting this on www.audisrs.com. There is a whole lot of experience on the board of the B5 S4/RS4. A quick search seems to point to N75, or possible boost leak.
I would get the system pressure tested.
I would also look for someone with experience with the S4/RS4 as they seem to have their peculiarities.
Cheers, I'll check that out...
Yeah, I figured that finding a S4/RS4 experienced mechanic might be a good idea - unfortunately not sure where to start looking, so I asked here :) Happy to take any recommendations that people have!
People seem to happy with Brodie European. I haven't tried them but will soon.
Quote from: vaudiw on May 10, 2011, 09:48:12 PM
Try searching or posting this on www.audisrs.com. There is a whole lot of experience on the board of the B5 S4/RS4. A quick search seems to point to N75, or possible boost leak.
P.S. The community at audisrs appears to be really awesome! Other forums seem to be full of jackasses (Audizine B5S4 forum, mostly)
Quote from: vaudiw on May 10, 2011, 10:01:27 PM
People seem to happy with Brodie European. I haven't tried them but will soon.
Brodie seemed to be relatively familiar with the S4 compared to some others
Took it to Brodie European this morning... They discovered a massive tear in the passenger-side Turbo->IC hose along with various other niggles. Ordered in the parts and invited me to bring it back for fitting next week when they arrive.
Very impressed with their service - probably will be my go-to guys even though they're way out of my way from the shore :)
Happy days, sounds like you'll have it sorted soon then.
Had the pipe fixed yesterday, took it for a drive for an hour or so - feeling very nice now!
And the codes/limp haven't returned! ;D