I have a misfire on cylinder 8 drivers side all the way back. Ive tried swapping coils with another and still the misfire. When i pull the coil plug on 8 it doesnt effect the engine at all. Any thoughts i was told it may be the computer its a 5.4 4x4. running out of options any help is appreciated thanks

 

Put in a new spark plug, it's a little cheaper then a computer. Just a little.

 

My 99 is dead on 2 and 8. If you take the plug wire off the coil will the spark jump to the wire or is it dead?

 

I tried changing plug and still the misfire and codes p0308 and P0358. When i pull the plug for the coil 8 no change in the way it runs.

 

It won't operate. Dead.

 

Could be a dead fuel injector.

 

Your gonna cause confusion - the OP has a 1999 5.4L.

 

That 358 is the PCM saying that it didn't receive a valid IDM pulse from the Ignition Module (which is now integrated into the PCM).

The coil driver within the PCM *may* have died. Be sure you have BAT + voltage on the RD/LG (power) wire at the #8 COP connector. Also, check that the WH/RD (control) wire at the #8 COP is pulsing while the engine is cranking/running.

 

Is there a difference besides displacement?

 

Different ignition systems.

 

Thanks. Good to know. I will shut my trap then

 

Ill be checking for the pulsing on the wire tomorrow. If it is a computer where is the best place to get one? I know ill have to tow ut to yhe dealer to have it programmed if i put a new one in. Love the expedition but its delaying my 48 f6 build but its the family vehicle so it comes first

 

Not necessary. Just didn't want everyone to misunderstand the process of zeroing in on the problem. In 1999 the 4.6 used a waste-spark ignition with coil PACKS, while the 5.4 that year used a DIS system with COPs (Coil On Plug).

 

IF its the computer, maybe alloro will chime in. IIRC, he found a source for PCMs that come with the correct software.

 

It's never the same place twice. If you post the number from the computer we can help find one.