DirtyBirdMKE

98 trans am M6....

I went through 3/4 tank of gas and got 160 miles.... i have a flowmaster exhaust, ORY and 3.23 gears (I know. Previous owner blew up old rear end and swapped the whole thing).......... I have a CEL i think for a bad O2 sensor. Its also got a tune from a hypertech handheld..

what should i look for in trying to solve this issue???

82cetuner

iTrader: (9)

you answered your own question, the 02

DirtyBirdMKE

i figured... i was just trying to get conformation

speedmaniac11m

Im curious to see how the frost tune changes my mpg on my 01 ws6. Ill have it all done tomorrow.

Empatho

iTrader: (16)

The bad 02 sensor is the biggest thing hurting your mileage. When my 02 sensor took a dump my gas mileage took one as well.

DuronClocker

iTrader: (25)

O2 sensor.... weather.. type of driving. I seem to remember getting about that kind of mileage in my '98 Z28 M6 when it was stock in the winter on short trips (worked 2-3 miles from home).

BigMac76

iTrader: (5)

Obviously the o2 will kill gas mileage because the car will default into rich/limp mode. Second thing that will do it as well will be the weather, winter formulated gas just doesn't get the mileage as it does in the summer. Third, how you drive the car, highway or city will affect it as well.

But like previously said, it's a good idea to change out the o2 sensor and go from there. My car is a 99Z with a M6 and during the summer I'll average about 26-28mpg, now in the winter I'm getting between 23-25mpg and also have a bad o2 sensor (P0161) pass side downstream.

Best of luck

prokilllsx

I agree with everyone else. Fix it then check your mileage.