RS4 (B5) Fuel Trim: Bank 1 & 2 (Mult): System too Lean

[Golich]

I have the following DTCs after the little engine symbol came on in the instrument panel- but car was running fine.

VAG-COM Version: Release 311.2-N

Control Module Part Number: 8D0 907 551 F
Component and/or Version: 2.7l V6/5VT G 0001
Software Coding: 04711
Work Shop Code: WSC 77881
Additional Info: WUAZZZ8DZ1N900775 AUZ7Z0Y1497437
2 Faults Found:
17538 - Fuel Trim: Bank 2 (Mult): System too Lean
P1130 - 35-00 - -
17536 - Fuel Trim: Bank 1 (Mult): System too Lean
P1128 - 35-00 - -

When I first got this code last week it was defined as intermittent. Agina the car was running fine. So I cleared the code and went for a spin. Logging the boost and MAF. There was no return of the codes until later this week during normal driving i.e. nothing mad.

My RS4 is standard. The highest MAF reading I get both then and now is only 230 g/s.

I was thinking the MAF might be at fault going on the fact that you guys think I should be 300+.

[DavidT]

MAF failure I expect. The maximum maf reading divided by 0.8 gives a rough hp figure, so a standard RS4 should be around 300 as you say.

[S2tuner]

The MAF on a stock RS4 should read at least 280g/s@6000 RPM. Anything lower than this and it's dead, plus with these faults, it is DEFINITELY dead!!!!

HTH,

Mihnea

[Golich]

Cheers lads its good to have a 2nd opinion.

I'd just finished writting the post above convinced it was the MAF went out to remove the entire MAF unit. (Audi exchange the MAF complete with the section of pipe the MAF is bolted into) I discovered the jubilee clip that holds the intake manifold flexi to the the alloy "Y" pipe was loose and the flexi came off in my hand!

I thought those fecking dealer techs didn't tighten this when they changed the plugs last month when it was in for its service. But then I thought well at least I don't need a MAF now - £85 saved!

Trotted off to the dealer to pick up my new rear wheel bearing and RS6 front flexi brake pipes required for my new RS4 8 pot Brembos, told the parts guy I didn't need the new MAF.

An hour later the car wasn't boosting - no engine light but no boost. 10mins later the engine light came back on. I'm well pissed off as by now the stealer parts section is closed early on Saturday!!

So now my max boost is 0.45bar while my requested is still 1bar. Max MAF reading is now 151g/s.

ON a slightly different subject. I thought a stock RS4 ran 1.1bar. I am not sure if I've seen that. The pre-limp mode logs over the last week have only recorded 1bar boost. I've yet to see even a spike above that. The requested is also only 1bar. Is this correct?

[Golich]

Changed the MAF - car on full song and no engine light

I must do some more data logging to compare sick with what I think is now healthy again!