I moved to Los Angeles, CA (Alt: 400 ft) from Reno, NV (Alt: 6500 ft)recently. My gas mileage in Reno/Sparks was about 340 Miles per tank. Now it is about 200 Miles per tank...any idea'*. I thought the computer would automatically sense altitude change and make corrections....

Help!!! 2.71 a gallon PREMIUM!

Thanks in advance, Craig

When was the last time you replaced the o2 senor and or fuel filter/air.

The computer should learn but how quickly is the question. Try hooking the battery for a good 1/2 hour.

See if that helps out.

When I purchased it in November of 2004, I did a complete PM on it. From Interior and Exterior Detailing, down to Wires, Plugs, All filters (except trans service), New loaded calipers with rotors, and a thorough cleaning and adustment of rear brakes, belts.

Disconnected battery terminal as suggested, I can hear a distinct "tone" change, so I believe that may have cured the problem...we will see on next fill up or two. But damn if the radio now doesn't work..LOC...I am the second owner of car...no codes left for me. My 93 SSE didn't have this AntiTheft portion on it so I never even thought to pull codes first. So this correction fixed a computer problem but expedited the non-working CD Player/Working Radio replacement sooner than I wanted to...for a remaned OEM one. No tunes for a week while another is in route.

Careful with the advice guys.....could have cost me more to have the dealer unlock it.

NV, welcome back!

All things being equal, the lower elevation should be better for mileage, not the other way around. You are suffering from a very well known disease called "Californitis" that affects Californians in the wallet due to the additives and gas mixture required for emissions. California gas is the worst in the nation, which is funny, since you burn MORE because of inefficiency problems.

HOWEVER, I wouldn't expect it to be that much of a difference. Is your torque converter slipping? Time for a trans flush and full tuneup, even another O2?

I speak from experience. I'm a native of CA (the upper half), and travel there quite often. I typically re-fill just before leaving OR in order to prevent the typical 10% drop in fuel economy. That leaves me enough to see the family and get back to OR on one tank.

They are probably using 10% gasahole additive.
Kills mileage.