Fault codes....

4.2 V8 40v Naturally Aspirated - 335bhp
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MingS6
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Joined: Thu Sep 17, 2009 1:14 pm
Location: Worcester

Fault codes....

Post by MingS6 » Mon Aug 08, 2011 12:14 am

My S6 has been a rolling project since I bought it! (2009). Nothing major just this and that. I have used Vagcom since early 2010 to keep an eye on the car. Since that point I have had an ongoing batch of fault codes in the Engine module. Performance on the road does not seem to be effected but now that I am using the car (I wasn't much before, just the odd 2 mile run here and there) I am noticing things can't be right as mpg is around 12-14 on average.

It has been rolling road tested since having it at PS and MRC with pretty much what it should be as the result.

Anyway these are the codes:

5 Faults Found:
16711 - Knock Sensor 1 (G61): Signal too Low
P0327 - 35-00 - -
17972 - Throttle Actuator (J338): Under-Voltage during Basic Setting
P1564 - 35-10 - - - Intermittent
16716 - Knock Sensor 2 (G66): Signal too Low
P0332 - 35-10 - - - Intermittent
17549 - Load Calculation Cross Check: Implausible Value
P1141 - 35-10 - - - Intermittent
17521 - Oxygen (Lambda) Sensor; B1 S1: Internal Resistance too High
P1113 - 35-10 - - - Intermittent
Readiness: 0000 0000

I have studied Vagcom and ran a check on the MAF using measuring block 002. It pulled 254g/s of air or (318BHP). This would indicate the MAF is OK.
I have also ran a check on 032 (fuel trim) but the readings were 0%. This was because I cleared the fault codes which reset the trim.

Audi would probably say a fault with the module as I have 5 faults. I would discount this myself.

I believe one issue may be throwing the other faults. It is plausible that both front lambdas are down, but both lambdas and both knock sensors seems unlikely. I tested the knock sensors a while back and they were in limits.

Throttle actuator under voltage during basic setting, Elsa says to perform a TBA (throttle Body Alignment). It does say this is required if the battery is disconnected. I have had the battery off a few times but never performed a TBA. Didn't want to throw confusion into the mix by doing one now either.

I have checked and found loads of articles on separate faults. Lots of reading with no single answer for any of them. I have not found anyone who has had a combination of the five!

I think performing an adaption run and checking the fuel trims will help diagnose the MAF. I understand the limits are -/+ 3% on the first (idle) and -/+ 10% on the second. Can anyone confirm this to be the limits for the fuel trim on an S6?

I am confused as to where the Throttle actuator issue sits with all this?

I have not had the covers off recently or found any split vac pipes etc.

Any quick win ideas guys?

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PhilT
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Re: Fault codes....

Post by PhilT » Mon Aug 08, 2011 12:58 pm

Is the ECU mapped? If so, who's map is it?
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MingS6
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Posts: 4
Joined: Thu Sep 17, 2009 1:14 pm
Location: Worcester

Re: Fault codes....

Post by MingS6 » Mon Aug 08, 2011 5:12 pm

PhilT wrote:Is the ECU mapped? If so, who's map is it?
No it is standard!

I took it out today

Scanned for faults before taking it out.
3 faults were picked up.
1 Knock sensor signal too low
2 O2 sensors, both banks, both pre cat

Took it out, did about 40 mile across the peaks (not perfect conditions- twisties, wet, altitude, average speed cameras and slower traffic). Anyhow it's where I live so no option really.

Fuel trim started adjusting and has settled at -0.9%idle and 0.8%malt.

I did a WOT pull in 2nd to around 6900rpm. Hit 262 g/s of MAF airflow. That equates to 327.5 Bhp at 1800ft asl running on 95RON. Not too bad!

Both pre cat lambdas then!?! huhmmm
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s6 on the peaks2.jpg

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