Hi Everyone,

I just bought an 1988 L98 GTA. The car has had a complete tune-up, an alignment, and the ECM shows no codes. The problem is that i'm getting 10 mpg city and 18 mpg highway WITHOUT pushing it (never sees the high side of 4000 rpm). Do you have any ideas why it takes so much gas?

TIA

Andrew

 

have you checked the o2 sensor? Id try that if it wasnt done during the full tuneup.

 

Yeah, check the o2 sensor, that's just horrible mpg.

 

OH NO I CAN'T FIND MINE!!!!!! WHERE IS IT...oooooooo yeeeeah

 

Thanks guys for the info. Isn't the computer supposed to throw a code for this?

 

Not necessarily... the computer has no way of knowing if it's just bad, as long as it sees some degree of response to its actions. Unplugging it or shorting the wire will set the code, and the reading always staying the same (no cross counts). Just being out of calibration, so to speak, won't necessarily appear as an error to the ECM.

Try replacing it. It's the most common cause of bad gas mileage.

 

Thanks RB, I'll go get a new one and replace it.

 

I just replaced mine a few weeks ago and picked up 3-4 MPG, it was only about $18-20 at Advance for a Bosch O2 sensor.