99 5.4L 4X4 80K miles- Had a long standing problem with shutting off after startup- seen other posts about this- not much more than a nuissance.

Now I have a new problem. The thing starting missing like crazing during acelleration. I changed the plugs and checked the primary of each coil with an ohmeter. I only checked the secondary on 3 of them (don't ask me why).

New plugs make the engine run much better overall, but did nothing for the miss.

I've got no check engine light on either.

I've pulled the wires from the coils one at a time and driven the vehicle. It seems to run the same.

I've pulled the wire from all but 1 of the fuel injectors (it was too hot to get the #7, I'll try later). It runs worse at idle, but basically the same under power.

The engine seems a bit weaker with any cylinder not firing, but it doesn't seem to affect the miss? Any ideas? Help!

 

Have you tried having the dealer plug it into the computer to see if you get any codes?

 

It's fixed- it was an ignition coil- don't know which one 'caus I mixed them up when I took them apart. BTW- didn't have any idea how much better truck would run on new plugs.

 

What did you do with the poop???

 

threw it down in disgust

 

My 2000 F150 5.4 last week acted like it wasn't running on all cylinders. Sure enough, the coil was faulty and it was running on 5 out of 8. The dealer replaced the coil/plugs and she runs like a champ again. By the way, my truck has 98,000 miles. 100,000 mile tune-up but 98 is close enough.