New here...been lurking for quite a while. Looking to buy this 98 F150 4.6 160k auto 4x2 from a friend of a friend. It has a real bad engine mis at idle but kinda clears up above 40mph. Dont wanna buy it if the engine is toast!
Yesterday, pulled each injector plug off one at a time and best I can tell is that #4 and #8 are not firing. What he/we have done so far is:
1. Intake Gaskets
2. Clean MAF
3. New Plugs
4. New Wires
5. New Fuel Filter
6. New PCV Hose
7. Seafoam and 92 Octane Gas - been thru about 1/2 tank so far

Any other ideas???? cuz I'm out of them!
Thx

 

Coil packs? Idk.

 

Any Ceck engine light? If its missing that bad something should be getting thrown as a code.

What about your sensors, like cam/crank sensors? I know it should be effecting alot more than just those two cylinders, but electronics do funny things.

 

Do a compression test.

 

A "How To" in the sig below -

 

is the truck throwing any codes??

 

4&8 are next to each other. Make sure the wires are right. Here's a diag -



Firing order ~ {1-3-7-2-6-5-4-8}

 

If everything is hooked up correctly - I'd say coil packs. I had the same issue on my '97 and replacing the coil packs did the trick. Idles so smooth that, a few times I was at a red light and I thought the truck shut off!

 

Doesn't matter, you should drop in a new engine soon anyway. At 150K I did.

 

Why? The limo guys are getting 400 to 500k out of 4.6's.