Hi All: I noticed recently that my gas mileage on my 98 Grand Marquis has gone down. I used to get 21-22 mpg now I'm dowm to about 17. I have not changed my driving habits. The engine is not skipping and runs as smooth as ever. Admitteldy, I haven't gone in for a major tune up. Someone suggested spark plugs and O2 sensor. I can problably tackle the plugs although it looks like I will have to remove the fuel rail I have never attempted this before. I have no idea how to change the O2 sensor. Should I try to tuneit myself?
98 Grand Marquis Poor Fuel Economy
Aug 25, 2003
4 Replies
Have they changed to "clean burning" gasoline recently in Houston? We just did here in the Austin, TX area and I noticed for the first time on a trip to Dallas last weekend that I was getting 17.8 instead of my usual
22-24 mpg > Hi All: I noticed recently that my gas mileage on my 98 Grand Marquis
Someone suggested it could be my O2 sensor or spark plugs. Would the car run rough if this were the case? I know that my brother has a 99 Crown Vic and has had to replace three of the coils (the ones on top of spark plugs) but the engine had symptoms of roughness etc. My car runs fine.
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