Car identity and help with error code P4092

[Pollock]

Hi guys,

Been meaning to put this post up for ages but now I have an actual fault with it now seemed to be the best time.

I got my RS4 about August time this year. Its a 2007 silver avant and it had about 50k on the clocks when I got it. The dealer that sold me it didn't have much info on it so I thought I'd check the forum to see if anyone owned it before me to see if they could shine some light about what mods have been carried out on it.

Heres what I know so far: -

Interior wise it has bucket seats, carbon trim, arm rest, tinted windows, cd changer but was unplugged for ipod cable.
It has a Milltek Cat back installed, I think its the non - reso model as its bloody loud but could be wrong.
It has a Gruppe M carbon intake.
It has had a remap but the dealer couldn't tell me anything about it other than he knew it had been mapped.

I took it to a rolling road to see what power it was putting out. It maxed out at 350 HP @ 7440 RPM, 305 ft.lbs @ 3910 RPM. Are these decent values for whats been done to it.

Now to the actual fault

I plugged my vagcom cable into it the other day and was seeing a pending P0492 fault coming up. I looked into this and it said it was bank 2 on the SAI.
I cleared the fault to see if I could drive around for a few days and have it go away. I had the battery off a few days earlier changing a bulb so thought it might be similar to the ABS warning that comes up about the steering angle needing reset.

After I cleared it I noticed that the readiness test results were different. Instead of just the SAI system failing, the catalytic converter, o2 sensor and o2 sensor heating also had failed/incomplete next to them.

I had a look around on the forums and thought that due to the car being mapped and the Gruppe M intake install that this might be a normal reading. The Gruppe M intake removes and blocks the vacuum for the SAI system and filters out the air pump going to the exhaust, I assume. Also due to it only happening recently in the colder weather could this just be a side effect of the mods on the car. I haven't been able to check with all the rain going on that the SAI pump might not even be there either.

Any thoughts?

Sorry for the long post and if I'm just repeating a previously documented problem.

Cheers for having a read.

Heres a pic of her in action at Silverstone back in November

[MikeFish]

Welcome and FON.
Don't know about the fault but you are massively down on power. Those sorts of rolling road numbers are normally down to a vacuum leak. Whereabouts are you? If anywhere near Banbury I'd get yourself down to MRC to sort the power issue and the fault codes (might be related). I'm sure if you give them the number plate they'll be able to tell you if they remapped it previously. If they haven't then you might as well get it done while there.

[MikeFish]

FYI a standard car with no mods and no carbon clean should be around 380bhp. Cleaned it should be around factory figures of 414.
Aftermarket exhaust and map should be around 390 before a clean or 420-30bhp when cleaned.
A vacuum leak will lose you about 60bhp.
I'd say with your mods I'm guessing it needs a carbon clean so you should be around the 390 to 400 mark without any faults.

[Pollock]

Cheers for the reply guys. I'm in Glasgow. Is that 400 at the wheels? I just assumed that I'd get about a 20% loss due to the drivetrain and left it at that. Can't wait to feel that extra 50 horse if thats the case!

Could I sort out this vacuum leak myself? Been looking at the self study guides trying to sort out what parts I should be looking at. Am I right in thinking it could be something to do with the combination valves at the back of the engine or one of the hoses leading to these. Iv got a vacuum pump so could see if these valves are holding up under pressure.

[Pollock]

Bit of a premature post there. Got a bit ahead of myself. Now I've had a look through the forum found out a few things.

Gonna try a hand vacuum pump on the vac hoses under the front carbon cover and see if theres any leaks.

I had run the output test procedure through VCDS and everything seemed to operate fine apart from the power flap but I'd be worried if it did since its not there any more.

Is the carbon clean really worth it. Surely a few track days a year and a bit of spirited driving in between would burn it all off.

I'm still at a loss with the o2 sensors and catalytic convertor. Does anyone know if there is some sort of time delay before those tests are carried out and passed or should it just test green straight away.

[MikeFish]

I assumed as you were in the uk and your 350hp was the estimated crank numbers rather than whp as we in the uk generally use the crank figure rather than the power at the wheels that is most popular with our transatlantic friends.

Carbon clean will get you max numbers back but will need cleaning again in a year so in my opinion it'd a waste of time unless you are chasing big numbers on paper. And no, giving it a good thrashing won't get rid of it, you might slow the rate at which it gets dirty but I don't think you can either stop it or reverse it without stripping and cleaning

[Pollock]

Cool. Cheers for the info. I'll check with ecotune and see if it is an estimate. I kinda hope it is so i can see what another 50 horse feels like.

[bluenosewrx]

A for audi in Clydebank can do the clean or autohuas, I'm assuming your maf sensor is gone and sounds like you definitely have a vac leak

[Pollock]

Cool. I'll have a look in VCDS and see what the maf sensor is saying. Still waiting on a dry day for the rest. The car is running fine apart from the readiness flags. Might feel a bit sluggsh at first start but no loss of power after that.