Hi guys. Car as per title, and has 120k mileage and generally in very good condition with FSH. Had new pistons, rings and rods courtesy of AUDI at 99K miles due to known oil consumption issue. Since then, but possibly coincidentally, has had intermittent throwing of CEL with codes P2279, 2178, 2188. Audi have had it back in and claimed they had fixed a leaking cam chain cover seal so should now be OK. But months later back it comes.

Seems to be triggered mostly when car has been run and left to cool for an hour or two. Didn't happen much over winter, and always starts first time if totally cold or totally hot. But if only warm, doesn't want to start unless I give it some throttle, then its a bit lumpy until back to hot, as if over-choked. Just occasionally it is REALLY lumpy when it happens and might even backfire or pop out the exhaust on the overrun. Then after 10 minutes the CEL sometimes comes on. If it gets past this point it is fine. It has the 2 distinct modes - a) normal working, and b) apparently over-fuelling a little, most obvious at idle, from which it will eventually recover with some normal driving. If allowed to stay in the faulty mode it will eventually put on the CEL.

So the P2279 code indicates an intake system leak - haven't found any leaking hoses (yet), and have changed the PCV but didn't fix it. Next plan is to take off the EGR and clean it - might be quite grubby and sticking as it was previously eating the oil before the new pistons etc. Might tie in with the strange temperature dependence? Or could be a faulty temp sensor? Any other thoughts guys? I see in a few posts about leaking HPFP seals, leaking injectors.....I have a fairly good code/live data reader but not so sure what values to check.

Thanks in advance for any advice.

 

8 months on and still got the same issue every couple of months. So the 2178 and 2188 codes are saying the ECU is richening the mixture at idle as much as it can, to counteract what it thinks is a vacuum leak somewhere. However, when in this mode you can smell the overfuelling in the exhaust, so possibly the vacuum leak 2279 code is wrong in the first place? MAF or O2 sensors perhaps? It has now just done it while stuck in standstill traffic on the motorway, flashing the CEL at me, and was lumpy mid revs for quite a while after, and checking codes later had added a misfire detected one. First time it has been troublesome in 'normal running' so a little worrying. Help needed please....

14th Jan 2022: Happy New Year all. Of course, the TFSI petrol engine does not have a separate EGR valve (it appears to do that function by juggling the input and exhaust valve timings and overlap), so I cant strip and clean that. Back to checking for induction leaks, or faulty MAF or O2 sensors - might try a squirt in carbon cleaner as the valves will be getting pretty gummy by now.......other nasty possibilities are leaking inlet manifold or injector, or worse still a blown rear seal.......nasty...

Any comments people??

 

Dear self (anyone else there???). March 2022 update:

Have now changed the MAF sensor. Initially thought this had solved it. Until first time it got up to temp and left to cool for 90 minutes. Then overchoked on restart, slightly lumpy etc, CEL came on. Read the codes before turning off - 2178 and 2188 again. Then read some live data, and spotted (for the 2nd time, but had forgotten to follow up..) that the crank speed reading was twice what it should be. I will check this on another obd reader, but surely this must be a faulty crank sensor??? Had left the engine running, so I cleared the 2 codes, but it still didn't feel happy and flashed the CEL at me. ANYONE ELSE HAD THIS WITH FAULTY CRANK SENSOR??

 

I have a 2011 with 161k. Last year I paid an indie shop to rebuild the engine due to the oil blowby. Recently the dealer called me in for a safety recall for the "crankcase pressure regulating valve". Naturally the inspection result was "no repair needed" and then they recommended about $5k in repairs. However, I am throwing it out there jic it may be an issue.