Hey everyone,

I have a 99 f150 with the 4.6l V-8. I noticed this about 10 days ago. While driving after the truck is at operating temp there is a stutter in the engine. It feels like when you are stuck in snow and someone else is pushing/rocking your vehicle from behind. You can hear what sounds like a wavering engine tone, but the speed and RPM are still moving just slower than before the problem. I can also drive through the problem and it will suddenly clear itself and run strong to the next gear shift. I found an exhuast leak that was fixed yesterday, I replaced the fuel filter, and cleaned the K&N filter. If anyone has any possible ideas please try and steer me in the right direction.

Andrew

 

Spark plug wires (if you have wires - not sure if they still had them in 99).

My 97 is very sensitive to plug wires, and I've replaced thme a couple times.

Use factory Motorcraft wires ONLY! You can get htem at a discount thru Tousley Ford in St. Paul: 10% over cost.

That's where I'd start; then plugs or maybe even the coils.

Jim

 

Clean your MAF. The K&N oil may be fouling it.

 

I cleaned it about 1 hour ago. Still doing it.

Andrew

 

A bit more info after I filled up with premium. I seems to have smoothed out some but is still stuttering. When I hit the gas easy no problem, when I roll in more throttle to speed up without kicking the tranny down it will hit about 2500 rpm's and start this route of spitts and stutters, all the while the rpms are climbing and mph is climbing slowly they are not jumping up and down. If I go WOT tranny kicks down and at about 32-3700 rpm it does it then clears and pulls fine. A friend who is a machanic said that it could be something with the tranny/torque converter that is linked to ecu. I also can hear a wavering exhuast tone as it happens.

Andrew

 

hey everyone,

Just an update to the problem with my truck. I took it to the local eagle speed garage. One cracked plug and one plug walked almost all the way out of the head. Thanks to everyone for all of the suggestions/ideas.

Andrew

 

Retorque the plugs to 28 ft/lb and do not use antiseize on them. This will keep them from blowing out.

 

I got this truck from my father 2 1/2 years ago. He had the plugs done 2000 miles before he gave it to me.

Andrew

 

dont know if this would help....but my 5.4 needs a throttle body cleaning every so often. i know its time when the truck wants to die at idle.

 

If one was almost out and another was cracked, you might want to check them all and retorque them.

 

My Mechanic did this. He had to trouble shoot this the old fashion way. He pulled plugs and checked all of them. He found these two problems and corrected it. The throttle body was cleaned last fall. I check that when I cleaned the MAF sensor and it is still very clean.

Andrew

 

Is your mechanic aware of the 28 ft/lb recommendation? It's not in any of the books, the factory spec is 15 ft/lb. I'm betting he just zipped them down by feel.