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Re: poor gas mileage, help! Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Mon, 17 Dec 2001 16:27:07
In Reply to: poor gas mileage, help!, dein, Mon, 17 Dec 2001 13:42:30 Members see ZERO ads on the bulletin boards and get more feature. - Help Keep This Site Online - Signup |
It's always important to have the plugs gapped properly, but I doubt that will be a big impact to fuel mileage.
I assume the mileage used to be better, and it has recently gotten worse. First thing I'd do is pull the spark plugs. How do they look? They should be a light grey color. If they look a fluffy black, you're running rich, and running rich also means lousy fuel mileage.
Check all the spark plugs, not just one or two. Are three looking good, but one is black? Or two and two? You may have sticky fuel injector(s) - they open up, but stick open and squirt in too much fuel. Fuel injectors can be cleaned, and sometimes running a tank or two of fuel with some quality fuel injector cleaner can help some.
The first two things to check are the O2 sensor (oxygen sensor) and the Fuel Pressure Regulator (FPR). If the O2 sensor is getting old and tired, it may be telling the engine computer that the engine is running lean, and the engine computer is responding by richening up the mixture. It's even possible that the O2 sensor is completely shot, in which case the engine computer will run the engine rich as a default.
The fuel pressure regulator determines the fuel pressure. If the pressure is too high, more fuel gets squirted into the engine, resulting in a richer mixture. There is a vacuum hose running to the FPR - make sure it doesn't have any leaks or is plugged. You may need to have the FPR pressure checked.
What is 'lousy' mileage? I usually get around 20-21 mpg with a turbo automatic in day to day driving, which is mostly around town with some highway. A manual tranny would provide a couple/3 mpg more. Highway should be around 25-26 automatic, close to 30 with a manual. But that's almost all highway, and no speed-racer.
Good luck!
posted by 140.157....
, Mon, 17 Dec 2001 16:27:07 <-- Viewing This Message
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