Mk6R - engine running rich

[AUC-05L]

Hi team!

I recently bought a problem....... I have been toying with VWs for ages but this has me stumped! have a mk6 R. engine is running rough and rich! Doesnt hold a steady idle fluctuates a fair bit. revs fine (backfires due to rich problem) drives fine.

the car has a stage 2+ APR tune. There is a APR sticker on the HPFP

When I scan it. it comes up with misfire codes on all 4 cylinders. Plugs all look the same. when i drained the oil it was definitely contaminated with fuel. i drained over 5L... so a fair bit of fuel mixed in with the oil

PCV - a common failure on these looks new. although that usually causes a lean condition not rich.

Anyone got any ideas of how to narrow down the issue?

Cheers

[Lucas_R]

Assuming it also has an aftermarket air intake, have you checked that all silicone joiners are not damaged and clamps are tight? Any air leaking after the MAF sensor will cause poor running and a rich mixture.

Also check all intercooler pipes for damage/leaks as this can also have the same effect.

Do you have any paperwork/receipts or info from the previous owner(s)? If the car has been modified to stage 2+ then its possible that the previous owner(s) went one step further at some stage and fitted the Audi RS4 injectors (probably along with an upgraded turbo). If these injectors were fitted, and then the upgraded turbo was removed and tune reverted back to normal stage 2+ then the injectors wont be scaled correctly and will be flooding the engine.

What other modifications have been done to the car that you are aware of? Basically anything mechanical or software related that has been changed could be the culprit.