Poor fuel economy
 

Hello Everyone,

This is my first post here. I have a 2002 6 cylinder camry with 145k miles. Since I bought it, I've gotten about 20mpg average, mostly highway driving, and this is based on my own calculations (fill up at pump, drive till next fillup and record miles, fill up to same level again and calculate).

I always thought this was low but the car functioned fine so I chalked it up to it being a 6 cylinder. A couple months ago, my battery died, and when I replaced it, the car wouldn't hold an idle on its own; I had to lean my foot on the pedal to prevent it from shutting off. I tried a different battery but the issue remained. After driving for about an hour, the issue had corrected itself. I spoke with the guys at Autozone and they told me that if there is some kind of imbalance, the computer system will learn and compensate for it. However, if the battery is removed, this learning is cleared.

The compensation is a nice feature to allow the car to function, but its presence is indicative of an underlying issue. My guess is that my low mileage is resulting from some sort of imbalance in the system - I'm not sure if it's related to fuel, air, electrical, etc.

Any thoughts as to what might be causing the poor fuel economy? Where should I start looking?

Thanks for you input.
-David

The engine is supposed to have an Air Idle Control valve that adjusts idle. But also has an electric throttle. The throttle setting might need relearning after a battery disconnect.

How is the acceleration?

Check for vacuum hose leaks, air intake leaks, plugged exhaust, bad A/F sensor, spark plugs.

Make sure the trans is shifting into over drive when hwy driving.