So i just recently bought a '98 V6 Camaro Atomatic with 127,000 on it. After driving it for the last few weeks I noticed that it seems to run out of gas awfully fast for a 15gal tank. I did some reading on this and various other forums to seet what kind of MPG people get with similar cars. It seems that 23-25 city, 28-30 highway is the norm. Yet last i counted mine I got 12 with mostly city, some highway driving.

Any idea why that is? I did drive around for a bit with the check engine light on because the stupid fuel cap seems to be impossible to close properly. Could that affect my mileage that badly? I counted my MPG by just filling the tank to full. Set the trip odo. to zero. And drive around. Next time I fuel up, just take the trip distance and divide by the amount of gas it took to fill the tank back up.

As an aside, does anyone make aftermarket fuel caps that don't suck and can actually close properly so you're not driving around with a check engine light all the time?

 

Could be the gas cap, most any parts store, plus dealer, should have one.
Visit Advance Auto and borrow the code reader, or buy one from Harbor Freight with coupon, and see what DTC's, Diagnostic Trouble Code, shows up.

Could also be an O2 sensor gone bad, or the PCM coolant temp sensor or its wiring gone bad staying in the 'cold' temp all the time.
Or could be a trans not upshifting to overdrive, or a bunch of other input sensors for the PCM.

 

stop by the local parts store and have them scann the computer for trouble codes. write down the code numbers and let us know what they are. could be any number of things.

 

Well when I bought the car, the tank was almost empty so i went to fuel it up and must have put the gas cap on wrong. On the drive home to NYC from NJ it threw up a check engine light. Couple days later I took it to a shop for them to jsut look the whole car over and see if there was any issues with it. (They replaced the drive belt and tuned and replaced the transmission fluid) Also told me the engine light was from the gas cap. Tightened it down for me and turned the light off. (Didn't think to ask them what the code was) Everything was fine from there.

Then a couple weeks later I fueled up again and again the light came on. Checked the cap, sure enough it seemed to be on a bit loose (it really seems to be too easy to put it on the wrong way) tightened it and went down to Auto Zone to have the code read to make sure it's not a real problem. I'm afraid I don't remember what the code was, I'll try to find the receipt they gave me. but it said the things you guys mentioned as possibilities for the code, O2 sensor, PCM, or gas cap. So I assumed it was most likely the gas cap. Figured it should go away since I tightened it down. And yep, just a couple days ago the light went away so I can't really scan it again.

I just have a hard time believing that a loose gas cap would cut my MPG in half.