2 Error Codes...Crazy hits 150K

[MaxRS6]

Hello all:

Crazy hit 150K and I took him for a spirited run. Around 120 he went into limp mode. I did a scan and have the following error codes. This has happened a few times with the same below error codes since I had the turbos replaced. It usually happens during full acceleration. During day to day normal driving and acceleration, I've had no issues. It seems to pop up during full acceleration or a high speed run.

2 Faults Found:
<O:p</O:p
17887 - Brake Boost Vacuum System: Mechanical Failure
P1479 - 008 - Implausible Signal
17963 - Charge Pressure: Maximum Limit Exceeded
P1555 - 001 - Upper Limit Exceeded - Intermittent

Later, I hooked him up to Vag Com and did some logs. I did three runs from 40 mph to 160 mph. The car ran fine on each run, and did not go into limp mode. I do note the actual boost is exceeding requested boost at times on the log. For example, on the below at around 4600 rpm the requested boost is 2000 mbar- yet the actual boost is 2330 mbar. For some history, when I recently had the turbos replaced, the car kept overboosting going into limp mode on each drive. They determined the waste gates were not set correctly, and had to pull the engine to adjust the waste gates. After they did this, the car started running normally except for the few limp modes noted above. However; I hadn't pulled any logs until now.

Anyone have suggestions on how to research/determine what is causing this intermittent loss of boost?

TIA Brain Trust

http://i827.photobucket.com/albums/zz195/MaxRS6/RS6%20Turbo/Log160mph.jpg?t=1317047801

[JSRS6]

Seems like they might still need adjusted. They are closer to where they should be, but not quite. It's enough to keep you out of limp mode most of the time.

[MaxRS6]

^Thanks for the input Josh. I suspect that may be the case, and have asked the tech for his review and input. I suspect it will be tuff to make this determination for them due to the work involved on their dime. However; I know/trust he will do the right thing if this does turn out to be the issue. It is a tuff diagnosis to make definitively. This will make engine pull #5 for the turbo replace odyssey if it has to go under the knife again. Oooof..;(

[JSRS6]

That's crazy, Crazy. Haha. Don't forget the usual suspect, n75. Could be intermittent.

[skribe]

^^ was going to say that. assuming you've replaced that along the journey.

[hahnmgh63]

Curious to see where the timing is at with Boost like that?

[MaxRS6]

^^ was going to say that. assuming you've replaced that along the journey.

The N75 was replaced when it was at the Audi dealership when they were trying to find the boost issue. It was the turbo not producing any boost. When I found that out after it being in their hands for over 5 weeks to diagnose the issue- I pulled it out of the Audi dealership as they were clearly inept at diagnosing issues. They thought it was actually the intercoolers, and some other minor items even though it was producing zero boost. They were plainly idjuits and I have had multiple discussion with AoA and provided them supporting documentation of the service managers lies and sorry service. LOL- I had a call the other day from the dealership's new service manager (yes- I hope I was partially responsible for the departure of the prior sorry a$$ liar they had previously). The new manager wanted me to return with promises of doing better. I told him I would never be unhappy enough to return to that sorry dealership (Parker Audi- Little Rock).


Curious to see where the timing is at with Boost like that?

I am going to try to pull some more logs this evening and I'll get the timing while I'm logging.

[MaxRS6]

throttle and timing angle included with log- 2nd gear pull WOT

http://i827.photobucket.com/albums/zz195/MaxRS6/RS6%20Turbo/Logtimingangle.jpg?t=1317131807The

Below is where it went into limp mode at 160. On row #3054 you can see where the ECU starts to cut boost. The throttle angle is also strange on both of these logs as I still had it WOT- yet it shows the angle to be less than 100.

http://i827.photobucket.com/albums/zz195/MaxRS6/RS6%20Turbo/Limpmodeat160.jpg?t=1317131915

[kismetcapitan]

I'm going to take a wild stab at this and say it's the hoses connecting the boost controller to either its vacuum source, or to the wastegates. I once had similar symptoms on my Skyline - the car would simply not boost according to where I was programming it. It was either over or under. The turbos were new. So was the boost controller. The Skyline has about seven hard pipes in the plumbing for vacuum source, wastegate connections, everything. There was a leak somewhere but I couldn't track it down. Eventually out of frustration I ripped all that out and installed three nomex-braided lines - one from the vacuum source to the boost controller, and two equal-length lines to each turbo. Everything suddenly worked.

[LIRS6]

I'd like to live where you live ... just sauntering out for a few 40-160 mph runs .. are we talking about a track .. a highway .. a neighborhood street .. your garage? Oh, and I know nothing of what your issues may be - sorry and good luck.

[JSRS6]

Randy, I would take a look at your n75 again. Your boost looks just like mine did when I had a bad one.

[MaxRS6]

Randy, I would take a look at your n75 again. Your boost looks just like mine did when I had a bad one.

^- I'll certainly give it a try- sure can't hurt. It is driving me bonkers- and I need to get it corrected relatively soon for another Ozzy adventure- Otherwise, I'm going to have some miatas and RX7s passing me on the straights..;0


I'd like to live where you live ... just sauntering out for a few 40-160 mph runs .. are we talking about a track .. a highway .. a neighborhood street .. your garage? Oh, and I know nothing of what your issues may be - sorry and good luck.

Probably should keep it off the public forum...;0- I will say it is done late at night/or early morning and zero traffic/bear risk

[MaxRS6]

Guys- Does it look strange that the throttle angle doesn't stay at 100% (note rows 405-416) when it is WOT?? On my other logs, the throttle angle was 100% throughout the RPM range when going WOT. Heck if I know- I'm a bean counter- not a car mechanic.

[JSRS6]

Throttle body adaptation, clean pedal potentiometers...

[MaxRS6]

^Thanks Josh-

The APR tune does have throttle body alignment feature. I'll give it a shot to see if it will make the log angles look normal.

[V8weight]

I would pull the throttle body and clean internally, then do a re-adaption....I think the actuators may be sticking.

[JSRS6]

That was my third thought in that train of thought, pat. I figured the adaptation first, then pedal, then tb.

[MaxRS6]

^Thank you Pat & Josh- I had the indy shop order another N75 yesterday to rule that out (or in) completely. When they install the N75 next week and test, I will have them do all of the above. We will see how that goes with getting a resolution. I will also have them completely recheck all the hoses to the N75 and the hoses down to the waste gates. They have done some smoke tests and say there are no apparent leaks. However; I want them to triple check. If the current Indy shop doesn't resolve the limp mode by next week, I've decided to ship it off to APR's corporate office in Opelika. I'm ready to debark this odyessy.

[MaxRS6]

Update- No love yet..The N75 replaced, new silicone hoses intstalled from the N75 to the waste gates. Crazy is driving me and the tech crazy. Sent logs to APR and their reply..

"From the logs I can tell that the car is overshooting the requested boost pressure that the ECU is asking for. This would be symptomatic of a leak somewhere in the n75 circuit or possibly a pinched hose in the N75 circuit.<?XML:NAMESPACE PREFIX = O /><O:P></O:P>
<O:P> </O:P>
The other thing we could look at is the N75 duty cycle which is shown in block 114"

The car is back in the shop as they continue to try to find the root of the issue. He may be headed to APR vedy soon to give them a go at the fun.

[SzymekCRX]

From these two codes I am guessing that we have a boost leak, probably through PCV system & Bbooster (suction jet pump in that case). Are the DVs ok ? Something's holding your boost when it should be already diverted. Even the N249 is suspected not to work correctly.

Just IMHO :)