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i have an 88 bonnie 165xxx mileages.

ac delco plugs
duralast wires

ac delco coil pack (magnovox)
ac delco ICM

K&N cold air intake.

AC delco O2 sensor.

i have no idea why im getting bad gas milage and it got worse after i replaced my o2 sensor

no CEL. does idle a little high but drops down and revs up

im getting 12 in the town. and its rediculous. please help


and this is off topic but the ac wont blow out the front vents? just at the top f the dash and at my feet... and it shuts off after i go from low to high... idk just killing to brds with one stone there

What sort of driving do you do? Stop and go? 2 miles to work, 2 miles back? Does the Check Engine light even work? Has the fuel mileage always been this bad? How long have you had the car? How is it on power?

RJolly87 wrote:What sort of driving do you do? Stop and go? 2 miles to work, 2 miles back? Does the Check Engine light even work? Has the fuel mileage always been this bad? How long have you had the car? How is it on power?

i work 4 miles from work, not stop and go, occacionally ill drive to the other side of town.. very little do i.

check engine light does work

i have had bad gas milage for awhile

i have had it since feb. but i bought it from a buddy who has said it has been getting bad gas milage since he bought i year and a half before i bought it

and the thing will pull anything you put it to and will get up and go whenever i make it. no power problems

The vents not switching tells me a vacuum leak. There should be a black odd shaped box on the firewall with a single vacuum line to it. That is the accumulator. I will post pictures tomorrow. It holds the vacuum needed to keep the vents where they are during low vacuum situations, for example when accelerating hard.

Vacuum leaks or a dirty MAF could be causing bad mileage. For vacuum leaks, you can spray throttle body cleaner around the engine top end while the car is idling. If the idle changes/hiccups when you spray a certain point, look for a leak there. You can also listen for hissing.

Clean the MAF filaments using rubbing alcohol or that same throttle body cleaner VERY GENTLY with a q-tip. You don't want to bend the wires.

On my old 87 Bonny my gas mileage dropped all of a sudden, from 425km per tank to just around 240km per tank. After checking a few things I finally found that the cable to the sensor on the airbox was unhooked and after plugging it in everything was fine again. No CEL was on either.