kingrancht

My truck has suddenly gotten horrible gas mileage. I was getting 11 mpg (nothing special), but now I'm getting 8 mpg. I have not changed the way I am driving. I have had all plugs and coils changed (could that of made it go down?). I have noticed that my exhuast smells bad also.
Any help would be appreciated.
Thanks

corey_lax

The new plugs are known to be a little worse than the originals as far as performance goes.... But when did you change them? What other sorts of maintenance have you done? When was the last time you changed your air filter/fuel filter/diff fluid/tranny fluid/cleaned MAF/ cleaned throttle body?

Horrible mileage all the sudden, I would think you need to change your fuel filter. Nothing else should come on all the sudden.

With that said, you have an old truck like all of us. You may need to prepare for some big repairs in the near future.

kingrancht

I had them changed late July. Ever since then my mpg has been bad. Guess it's not that sudden, but ever since they were changed it has been bad mpg.
I haven't changed or cleaned any of the filters or any of that. Is that where I should start?
I have not done any other maintenance.
My truck is stock except for a sct tuner

Summers22

iTrader: (2)

What plug brand is in there? All the COP's good?

Especial86

iTrader: (1)

Check all the plugs and make sure they are tight. I would also check to see exactly which plug is in there.. These motors in stock form prefer the sp515 plugs the best. Make sure to add dielectric grease to each cop boot before you reinstall the cops..

Also, like stated earlier, be prepared to get the normal maintenance items replaced and renewed.. The fuel filter and oil should be a top priority if you have not addressed them already.

tritonbullet

Any opinion on which fuel filters to use?

corey_lax

Change your fuel filter and air filter and unhook the battery for 15 minutes. Those are cheap fixes that you should do anyways. Clean your MAF and throttle body while youre at it.

Especial86

iTrader: (1)

Motorcraft, purolator or wix are good fuel filters.. I'm running a duralast filter now with no issues..

tritonbullet

I was gonna snag a filter from work I forget what brand they are..some shop brand I think mighty..I haven't changed mine in like 25k

Especial86

iTrader: (1)

Any brand filter will do the trick.. If you start having issues with the no name filter, then swap it out for one of the other brands I mentioned.. They are cheap and very easy to change, so I wouldn't sweat it to much. But I would change soon if it was me.