I am getting terrible fuel mileage

LEYVA1991

MEMBER
2008 CHEVROLET AVEO
89,000 MILES

I have a 08 chevy aveo and I work 80 miles away from home, the car is supposed to get 34 miles to the gallon, so I drive to work and back and the car is completley empty, it is wasting to much gas that my 4x4 silverado is getting better gas mileage than the car, can it be the o2 censor, injectors or fuel lines, or fuel pump?

1 Reply

CARADIODOC

MECHANIC
33,916 POSTS

The engine can't burn that much fuel without there being black smoke from the tail pipe. You either have a leak or someone is siphoning your gas.

If no leak can be found, you'll need a scanner that displays live data to view the fuel trim numbers. If they are high positive, the Engine Computer is requesting more fuel. If the numbers are high negative, the computer is trying to reduce fuel without success.

A cylinder misfire, a vacuum leak, and an exhaust leak ahead of the front oxygen sensor can all introduce extra air that will be detected by the oxygen sensor as a lean condition. No matter how much extra fuel the computer commands, there will still be that extra unburned oxygen. O2 sensors only detect unburned oxygen, not unburned fuel. The computer can only adjust fuel metering about plus or minus ten percent beyond factory programmed values.