A5 2010 2.0T FSI (211) - Carbon Build Up Issue!!??

[rob78]

I bought an A5 Sportback 2010 2.0T FSI (211). Car was previously used as a company car so mileage is fairly high at 87k but it was priced a good 3k less than any other equivalent A5's so I plumped for it.


Anyway, since buying it, I've have had an on-going issue with Engine Management Warning Light (Amber one) coming on intermittently. It normally stays on for a couple of days and then goes off. There is, however, definitely some underlying issue with the car.
When I run the car from cold it's is fine - starts up and runs smoothly. However, if the engine is off and re-started later (engine at running temperature), engine really struggles to ignite. Last night it took 3 attempts before it finally turned over. The other issues are that is it is rough when idling, misses in the low rev range when accelerating and here is the weird one; the average MPG reading shoots up a lot higher (34MPG compared to 25 MPG, for example) than what it should be.


I have taken the car to an independent garage (VAG specialist). They couldn't diagnose the problem based on error code but what they did say was the fuel was too rich when the car was idling.
I took the car to my local Audi garage. They said they couldn't pinpoint the exact problem but it would be one of two things: leaking fuel injectors or spark plugs and air filters needed replacing. They checked the fuel injectors and they were fine. I've since had a full service with genuine Audi parts done by my independant garage. Suffice to say, the problem is still there.


I have little confidence in Audi and dont want to take it back there (and run up a small fortune in labour charges). Based on the symptoms and doing a bit of research, my gut feeling is that it could be the dreaded "Carbon Build Up". Is there anyway to determine this - any leads I can give my mechanic? Any other ideas what it might be?

NB. Not sure it's relevant but it has had the work done to fix the known issue with burning oil excessively (piston rings work)

[rob78]

EMWL came on again. The error codes were:
2822-P2178 System too rich off idle bank 1
4106-P2188 System too rich at idle bank

I've booked the car in with my local Audi Specialist to look at on Tuesday.....

[Doctle Odd]

Get a VCDS scan, what diagnostic is your VAG specialist using