Hey guys, my 2004 2.7t a6 geting about 16.7-16.9 mpg onaverage and no more then 20.5 mpg on the higway at around 60mph. What could cause this? I did removed both of the downpipes and completly gutted them, could this be a cause? Also check engine light comes on and off, coed says its o2 sensor.
I also heard that I can shut them off completly once i do a comp chip. If i do apr stage 2+ and shut off rear o2 sensors u think my mpg will get better? thanx a bunch!

 

Anyone?

 

Is your 16.7 MPG calculated or are you getting it from the car computer?

 

The rear O2 sensors do not adjust fueling at all, they are there to indicate cat efficiency. Mine have been coded out in my tune. I also get far better MPG than you with a full stage 3 car

 

bad o2 sensors cause the computer to default to thier rich safety maps. Rich A/F means less mileage. and like nothing77 says... stage is not designed to be efficient.

 

So if would do a tune, something like stage 2+ (well i thibk i got anything done for stage 2+ anyhow so), I could shut off rear o2 sensors and my gas milage should be better then what it is now? I mean I understand if u get 18-19 mpg with stage 3 just because you push more power, but when your car near stock and u get 16,9 thats kind of not right.

 

no the rear o2 sensors do not effect the engine. I agree that your mileage seems a bit low. I;m stock and I swear I get like 30 miles to the gallon on the highway. Is your driving style involve a lot of open throttle? Best way to instantly improve mileage is to adjust driving style. how many psi are you running in your tires? Do your wheels need alignment? Have you cleaned your MAF lately?

The CEL is probably coming from your piggies. Did you relocate or modify the 02 sensors after the gutting?

 

I usualy do drive fast, but for about a whole week a drove like a grandma, i dont think i went over 65. My average was still 16.9 mpg. After i gutted down pipes I instaled that noun fouler and then put a o2 in it, didnt had any coeds for about 1000 miles or so.