I'm new and have searched till I'm blue in the face. . . but I needsome more input. My truck (a 98 F-150 Lariat) has been extremely well taken care of. I have done the TB cleaning prior to finding this site. The truck has 90K on it, I have just replaced upper and lower radiator hoses as well as the belt, as well as a tranny and radiator flush. The truck seems to have a stutter between 1500-2100 rpms. It just seems to catch sometimes, however to CEL or warning lights. Problem isn't evident when more throttle is used or when accelerating at WOT. The wiring harness isn't touching the AC condensor nor anything else. I know it has the COP ignition system, and that it can be troublesome.

Does anyone know whether the problem is with plugs, the wires, TPS or MAF? It idles fine at cruises fine, but just has this hiccup on slow acceleration and I havent been able to find a definitive answer when searching. Thanks!

 

have you tried replacing the fuel filter? and i would also suggest using seafoam... its a pretty good product and many from the sight have used it. i would use in it the vacum lines and in the gas tank every oil change. Hopefully its just a bunch of gunk crap in there. hope that helps..

 

used chemtool B-12 on the TB's, and put seafoam in the gas tank last oil change, sorry ofrgot to mention that.

 

Man, I love this new web page design!

Sooner,
With 90K, have you changed the plugs yet? If not, it's about time to change anyway but could contribute to your hesitation, stutter, what I call, "The stumble."

 

well i would try the fuel filter. and i would check the pvc vavle and hose leading to the back of the engine ... its prone to cracking and the pcv is only like 4 bucks. my truck wouldnt idle properly and i finally went on a lim (the pcv valve passed the self check i did which i read out of a repair manual) but i replaced it anyways and it fixed the problem. other then that i would check for gasket leaks. it may be a timing issue but i dont kno enough about that to lead you in the right direction. hopefully someone comes on here and either backs up what i said or gives you more info. sorry i cant be of more help, just trying to help you out with the things i had go on my truck.

 

Here is what got rid of my hesitation problem with my 2000 5.4:

- Used two cans of Sea Foam (1 for Intake, one for gas tank)

- Cleaned MAF with electrical cleaner

 

Well it idles fine, no miss at idle from what i can tell. Like I said I've cleaned the TB and used seamfoam in the gas tank within the last 3-4 tanks of gas. I don't think the spark plaugs have been replaced except for one when the truck kept dying at idle because of a faulty cop ignition part that the dealer replaced under warranty. I plan on doing the plugs soon and cleaning the MAF sensor.

At this point, what cleaner can be used on the MAF, i thought I read that someone had used windex, but don't yell if thats bad to do. Secondly, if I replace my plugs. . . which brand/type do you recommend and do I need to put any locitite-type stuff on them because of my reading about plug blowouts?

Thanks again guys

 

i havent changed plugs yet but as far as cleaning the maf DONT ACUTALLY TOUCH IT!!! buy some electrical contact cleaner ( i got mine at the local auto zone) and spray the he// outta the maf. keep all the tubes by the maf off so when it evaporates it wont go in to the engine(it wont hurt the engine i just didnt like the idea of burning that crap, im picky what goes in there ) let it soak and spray a couple more times... be very carefull not to touch a thing with ur hands or anything... the little wires will break instantly .. trust me.. its pricey to get a new one

 

So far so good. . . I bought another can of chemtool b-12 to clean out the TB and every rubber hose I could get my hands on to spray that stuff into. Even though I had already done the TB 3K earlier, I did it again anyway. I bought some electric contact cleaner at Orielly Automotive (I love that store so much more than Autozone) and sprayed it multiple times on the MAF sensor wires. Soaked those and let them dry about 3-4 times. Then listen to the engine grumble to a start choking down that chemtool.

And voila, after letting it run enough to smooth the idle out, I took it for a test drive and NO STUMBLE! I still plan on replacing spark plugs just cause it needs to be done, but the stumble between 1.5Kand 2.1K rpms is gone. Hope this solves it for me. . . thanks for all of your help guys!

 

yep no problem, if you never have cleaned the maf before then more then likely that was it... they get pretty dirty and who knows why ford didnt make it a maintance item cuz in reality it is. i spray it down every 20-30k which is probably over kill but hey better that then never.