BADFAST

I have a 2002 F150 4.6 5 speed. about 8 months ago i was driving down the highway and it started misfiring, check engine light came on and i took it home and scanned it. simple enough it was a coil pack on cylinder 2. new coil pack was installed and ran perfect. about 3 months ago same dilema. this time NO check engine light. feeling maybe there was still a code there with no light i scanned it again. nothing showed. it wasnt to bad so i continued to drive it. about a month later it got worse. so i scanned it again. nothing. it doesnt run bad at a constant speed, but only when you get on it and the demand is there it will misfire and fall flat on it's face. thinking it was a fuel problem ive changed fuel filter and pump and also checked for plugged injectors. still same misfiring. it makes 30 psi at idle and 40-55 down the road. which if im correct is about dead nuts for these motors. after that i changed the Throttle positioning sensor. nothing. i swapped a used air flow sensor in and still nothing. also tried cleaning both of them. also unhooked vaccum line off egr and no result. ive pulled the plug and it was white. no black carbon on the plug to be found. so it obviously has no fuel to the cylinder. i would think if it has good psi and clean injectors it has to get fuel? or if it was a coil pack it would throw a code after 8 months right? im just tired of putting time and money into this truck. any info or thoughts would be GREATLY appreciated. thanks

louie83814

Have you checked all your wires? Mine was having the same exact problem with no check engine light. I took off my wires one at a time and tested with a volt meter and found that they were off from where they needed to be or had no continuity. I changed them with some new plugs and it is running like a champ now. Mine was topping out at 54mph on hills at close to 5k RPM, took it up a grade after the change and 70MPH no problem and just towed my camper over same grade. So I would check those too. Good luck.

cgouldy

Checking with volt meter where do they need to be?

BADFAST

mine has individual coil packs instead of wires. im going to change plugs and packs but it just seems odd that the plug showed no fuel. thanks for the info though!

udderbrudder

I wouldn't assume a fuel problem just because plug didn't look bad. I have posted many times on this topic (as many other members have). If you use the search option you'll surely come up with some info. Good luck.

1997F150XLT

How did you do your injector test? It could be that you have a bad set or injector wires. Also you should be able to hear the injector clicking if it is working at idle.

19674x4

change all your plugs, and wires. overgapped plugs will cause a miss under load.

BADFAST

i pulled the injectors out to make sure they werent plugged. i also hooked a fuel psi guage up to it and put underbwindshield wiper while driving and it carried 50-60 psi. my plug gap was right about at .062. that could be my problem. i think normal is .052?

19674x4

normal is .52-.56. they are WAYYY over gapped.

BADFAST

i guess that would make sense why it got worse over time. thanks for the help i will let you know how it goes