My '97 SE has an exhaust, y-pipe, intake, and straight pipe (no cats!) and gets 26 miles to the gallon. Gas mileage has steadily gotten better as I've added more performance parts, however, I fear this is cuz it's running lean..could I have been putting some bad strain on the engine during this time of Camry gas mileage? I will be getting my ECU re-programed soon to remedy this problem. I'd must rather be getting 20 miles to the gallon than 26 if it means I'm not screwing up my engine. Anyone else have this experience?

 

Depending on your driving habits and conditions, 26 mpg is fine. Pull your plugs and compare them to the pics in the back of a haynes manual.

 

I get 27-28 on highway alone. So what are your conditions? I doubt that simply running lean will give overall BETTER efficiency to the vehicle, so you're probably fine.

 

my check engine is on, for 4 months i have a bad O2 sensor, i know which one, but i'm lazy and dont have time. Anyways , i just took a trip to the smokey mountains and back, and on the Highway, i averaged around 26- 28 MPG, going 85 - 95 mph+ ( with bursts of up to 120 , had to keep up with buddys 330CI).

 

You're fine, it's not lean, dont get a reprogram to richen it out, if you want more power, any of the aftermarket ecu's actually LEAN it out to make better power, your engine is not straining, its actulally the opposite, running more efficient.

 

Thats normal gas mileage just be happy dont do much city driving.. I average 18mpg

 

Your o2 sensors are constantly reading the A/F ratio and adjusting the air fuel mixture to make your engine run correctly. Unless your boosted there is no way your engine can run lean with bolt on mods.

Enjoy your good gas mileage.