hyperzone

Its really weird that this post is here now... I just encountered this same problem. filled up a week ago, did the math (10mpg), and was like "WTF?". I thought maybe it was a mistake, like maybe my wife reset the trip meter or something... Filled up yesterday and it averaged 11 on that tank. Ran it to jacksonville and back for some things and had autotap setup to watch the O2's, timing retard, STFT & LTFT. I'm not an expert at reading all this stuff yet but, the STFT was pretty close to 0% only deviating at most 5% that I noticed. LTFT stayed around 0% and deviated no more than 3% that I could notice. O2's were bouncing back and forth like expected so... what else should I look at? What could cause such a shift in gas milage? My usual in the past was about 16-18 mixed driving. I'm suspecting (for other reasons) I may have some exhaust leaks and I also may need to adjust my valve lash but, could those things cause that much of a drop? Also, the car drives great, I cant feel anything unusual.

hyperzone

Figured out my problem. My trip odometer is crapping out. The main odometer is good but the trip meter is barely moving. Like, I drive 15 miles and the trip meter moves 1-5 miles. Its great to find out thats all it was although, cant believe It took so long to notice. Then again, I would only drive the car occasionally and once I thought it had a problem barely drove it till I had time to look into things. Only noticed it by accident too. So, I can scratch that issue off the list now.

1995blacktattop

iTrader: (2)

to the OP

yeah that seems a bit low. how new are your plugs/wires?

i normally got ~ 14-15 city and 19 highway and averaged around 17-18 and then one day a few years ago the gas mpg started averaging 12 or so. i took the car and had the plugs/wires/fuel filter changed (it was right around 100k miles) and was right back to normal. i just took a 227 mile round trip with some spirited driving but also a lot of 70mph highway driving and averaged around 18