89 f150 idle
Senior User
Joined: Oct 2002
Posts: 150
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89 f150 idle
everytime someone does a tune up due to bad gas mileage they usually forget a very important part which is the o2 sensor. If you have bad gas mileage and no trouble codes, then try replacing the sensor and maybe the fuel filter as well. But def. the o2 sensor as this tells the computer what the end result is ogf all the air and fuel going into the engine.
