built2crash802

Hi all,
2.0T Manual, I've had it for 2.5yrs gas milege has always been 26-29.5mpg. Just brought the car in for service cause of hesitation and bad mpg (19mpg), turns out it was carbon build up so they scrapped it off put in a new gasket. I convinced them it was becuase of the oil consumption and got out of it free. Any way, hesitation gone but MPG still around 21. My thought is carbon build up on the O2 sensor or MAF sensor causing bad MPG. Anyone have any ideas?

jagtoes

Did you get any codes? Also did they replace the plugs ? Did they clean or replace any of the injectors? How many miles on the car? If it were an O2 sensor it should throw a code.

built2crash802

It was throwing misfire codes at the dealers, on a couple different cylinders. Plugs were replaced at 37k, car has 60k on it now. after carbon clean up there were no codes.

Dolamite

Check your fuel trim. I doubt it's the MAF very highly. The o2 sensor, also unlikely. It's possible to check the o2 sensors using their diagnostic software or you can yourself with vagcom. Did you tell them you were getting poor gas mileage? You need to check your AFR.

I test drove a new 2014 b8 2.0t tip for a week and didn't average more than 23mpg.

built2crash802

AFR?

jagtoes

Air Fuel Ratio. You would need to plug into the OBDII port with a diagnostic tool to find out this reading.