Hello everyone,

1998 f150 4x4 5.4L

Yesterday, for no apparent reason, I started to idle rough at a stop sign. As I accelerated, the truck was shaking. The exhaust note sounds very different.

What could the problem be?

My only mods are a K&N FIPK and a Ravin exhaust.

I was thinking that I was firing on only 7 cylinders, but I only have about 30k on the truck?!?!

Please help...

Thank you very much!

 

I think your on the right path with a cylinder misfire. Pull the plugs one at a time and see what they look like. Spark plugs can tell you a lot.

-Jon

 

You'll probably get a computer code soon.

At your mileage it is probably a bad plug/plug wire/coil pack.

I had one plug and one wire go at your mileage. Mine is 98' too, 4.6L.

Dealer ripped me off. Should have bought code reader right away.

Try cleaning the little wire sensor on your MAF first with a q-tip dipped in windex. Be gentle though. Don't want to break that wire!

Also, try pulling one plug wire from the coil packs at the front corners of the motor. Do one cylinder at a time (shut it off between wire changes or you'll shock yourself silly) until you find the bad one. You'll find it when you remove a wire and the engine still runs like crap but the idle doesn't change from your all wires connected idle. Then you've found the defective one, assuming it's the ignition wires/system. If you remove a "good" wire then the motor will run even worse.

 

Sounds to me like it's trusty 'ol coil pack #4. The heater hose right above it leaks directly on to the coil and burns them out over time. I can gaurantee it's the #4 coil pack, pick one up from Ford and replace it, it's real easy. Cover it in foil to keep the fluid off it later. I had this exact same problem with my old '98 5.4 and from what you've said it sounds like #4.

-Kelly

 

Thank you guys very much.

I appreciate the time you took to reply!

Mechanic told me it was a coil/wire/plug screwup.

Thank God its not a long operation!!! I need my truck for this weekend!!!


Take care...