Hey guys,

Need help in trouble shooting what is going on in my car to cause degrading gas mileage. I have a 97SE with 142,000 miles. Usally i get a minimum of 340 miles per tank but lately I have been barely able to get to the 300 mark.

I just recently changed the fuel filter, air filter, cleaned the trottle body and have also put a bottle of cheveron fuel system cleaner. I have no check engine lights, I even tested the computer by putting it in diagnostic mode to see if it gives me any codes but nothing. Tire pressure is good and no other problems with wheels or anything so I am not sure what is causing it.

Can it be O2 sensors? but dont they give a check engine light if they go bad?

can anyone think of anything else that might be degrading my gas mileage?

-Ken

 

It could be a bunch of things causing poor gas milage. lazy O2 sensor, incorrect reading on coolant temp sensor. To be 100% sure whats causing it you'll have to get you secondary ignition scoped to see if you burn mixture is correct, This is not done by a scan tool or bring it to a diagnostic shop (not pep boys or autobarn). You gota go to a shop where the specialize in engine diagnostic. Other wise your gonna just guess what the problem is. And it can get expensive just throwing parts into a motor with the hopes of getting to the source of it. It should run you under 100 bucks to get it checked out. I wouldn't recommend the dealer cause they have a habit of just selling parts until they hit the problem at your expense.

 

i would recommend pulling the plugs and checking their condition. if its time to replace then go ahead but even if it was not that long ago, you may want to pull them and see if it has been running rich. also, how is the alignment?

 

Alignement is fine! Also plugs were changed at 120,000K as recommended. Its at 140K now.

Humm...guess i need to get it diagnosed.

I also notice a vibration at times and other times its not there...not sure what can cause that.