Bad Gas Mileage after Fuel Induction Serv
 

I have a 1997 F150 5.4 that starts up and runs like a top. I recently had a fuel induction service done on my truck and now I am getting really bad gas mileage. Truck went from about 14 to 10 and the last week I checked it was at 9. Driving habits haven't changed..I do idle it a little longer now that it is winter here in Buffalo but this is driving me crazy. Changed gas stations, looked for non-ethanol but you can't buy that here any longer here. Had the plugs changed, fuel filter changed, cleaned the MAF. I just don't know. Could it be an o2 sensor? I have no check engine light on.

Would not a the check engine light come on if it was the o2 sensor? Any help or advice would be appreciated

Letting it sit and idle isn't helping any, I read an article on yahoo news today talking about that.
http://autos.yahoo.com/articles/auto...car-in-winter/

Mine did the same thing. You need to let your computer adjust the injectors again. I would say after 100-150 miles my mpg went way up.

It has been several tanks of gas and the mileage is getting progressively worse. I have no check engine light

Its likely just a coincidence of changing to winter mix gas which is known for much worse fuel mileage (I think, or is that summer gas??) :)

The 02 sensors can be bad without throwing a CEL, if yours have some mileage on them and haven't been changed it may not hurt.

Might also try resetting the PCM by pulling the battery terminal off for 5mins or so and see what that does.

Winter fuel mix is more volatile and gives downgraded MPG. Just a coincidence you did the injection clean while winter mix is in your tank

I agree, probably just a coincidence with the injection clean. Keep in mind that the the use of defrosters turns on the air conditioner compressor which will use more fuel. Is this the first winter you owned the truck? If not has the truck had a lower MPG in winter? Years ago had a similar MPG reduction, change plugs, no help. About a year after that air conditioner compressor went bad and had new installed. After that MPG went back up to where it should be. My guess bad clutch on air conditioner compressor. Good Luck.

Surprisingly these modular trucks use a hell of a lot of gas while idling/warmup. Warm up will drop my 14=16 mpg down to 12 or less when I let it warm in cold weather. I can get great highway mileage but idling uses more than driving for some reason it seems.

We have real gas here in AK, no ethanol, but even at that, they do put in additives, so our winter fuel mileage goes to heck like everyone else's.

My mileage was better, truck was prettier back when this old thread began.

LOL, Jbrew