Hello,

Since sometime late last year, my '03 F150 w/5.4 has been getting poor performance and fuel mileage, as well as a bad idle. It feels like it is having a miss under idle, because its just a slightly rough idle.

It doesn't appear to change depending on whether or not it is hot or cold. Also, when I first start it up, it often stumbles upon my first acceleration (after the engine has been allowed to cool all night).

I have replaced the spark plugs because they didn't look so great (got some Bosch Platinum +4 plugs, they seemed to give me a bit of performance back).

I have had it in to the dealer early this year, when it wasn't quite as bad, and not reproducible, and they could find nothing wrong. I took it in this Monday because it pretty much always idles like that now. However, they still can't find anything wrong.

I'd like to get my gas mileage back up to what it was for the first 7 months or so (I custom ordered this truck and received it Jan 27, 2003).

I've read a LOT of threads about similar problems, but haven't seen anything conclusive come from it. I am trying to figure out if I can test the coil packs, since it very much seems like it has to be an ignition issue.

The dealer isn't much help, because every problem I've brought it in for has met with much resistance. I had a horrible rear-end whine that took me 3 separate visits to get them to even admit that it was a problem.

I don't want to start replacing things wholesale because thats a good way to empty your pockets.

Any ideas?

 

is it under warranty ? They shouldn't be hassling you if it is. And if it is, is there another dealer besides that one around ? Most dealers should honor the warranty for repairs. What about a computer tweak? ?????

https://www.f150online.com/galleries....cfm?gnum=4362

 

They aren't charging me for the diagnoses (it is indeed under warranty 3yr/36,000), however, if they cannot diagnose it, I fail to see what good it will do to bring it in time & time again.

I have half a mind to take it to a trusted local mechanic and have him find the problem then go to Ford and make them fix it.

I don't personally have the time myself to figure it out. If it wasn't causing fuel mileage problems I wouldn't be so worried, but that = immediate and future money.

I will admit to being a perfectionist in my vehicles. Heck, for that one reason I doubt my 74 Nova will ever be "complete", lol. But, even though I may be accused of trying to make it perfect, the fact remains that a new vehicle shouldn't be idling roughly and have a major drop in gas mileage.

I almost expect the SES light to go off the day the warranty DOES expire!