Misfire out of nowhere

[Barwick]

I'm pulling out of a parking lot today, and all of a sudden the car starts to stumble a little bit, then a little more. I pull up to a light and put it in neutral and it's still stumbling pretty bad.

End up taking it to a parts store and they check the codes, Cylinder 1 AND 6 misfire, multiple codes each (I think there was 3 check engine triggers reported for each cylinder, as if they're both misfiring at the same time).

Any ideas here? I've done the valve cover replacement and had zero problems after that, also changed the plugs when I did that. Do cylinder 1 and 6 fire at the same time? Possibly a grounded signal wire to the Coil On Plugs on 1 or 6, maybe if the two cylidners are linked together somehow?

 

[eL eS]

If youstill have the 1st gen coils intstalled then it could be the insulator boot. Often they would develop pinholes in them that would allow the coil to fire to the chasis rather than the plug.

You could replace the boot but since you would be doing all that work I would suggest you replace the coils.

 

[Barwick]

If youstill have the 1st gen coils intstalled then it could be the insulator boot. Often they would develop pinholes in them that would allow the coil to fire to the chasis rather than the plug.

You could replace the boot but since you would be doing all that work I would suggest you replace the coils.

I swapped coils 1 & 4 today, and took it to have the codes re-checked. Problem stayed at coil 1, it did not move to coil 4, so I have no clue where to look now.

 

[mholhut]

Did you have the codes cleared after you had them originally read? If not, the code will still exist for cyl 1.

The problem with coils is that they are most likely to fail when they are heated... so they may exhibit signs of misfire but not permanantly fail, or trigger the CEL until the engine heats them up.

The fuel injector for cyl 1 may also be the culprit.

 

[Barwick]

Did you have the codes cleared after you had them originally read? If not, the code will still exist for cyl 1.

The problem with coils is that they are most likely to fail when they are heated... so they may exhibit signs of misfire but not permanantly fail, or trigger the CEL until the engine heats them up.

The fuel injector for cyl 1 may also be the culprit.

Yeah, I had them cleared, and 3 for each cylinder came back again, 1 and 6 still, even after I switched them.

I thoguth about the fuel injector too, but it's really really weird that two cylinders started misifiring at the same time.

 

[mholhut]

Not really that rare for two of them to go. Happened to me a couple times. Have the coils load balance tested at the dealer and replace the one's that fail... not just the ones that set off the CEL.

 

[Barwick]

Well, I pulled off the "harder than it should be to get to" cover over the coils on the passenger side, and unplugged the #1 while it was running, and it stumbled way worse, plugged it back in and did the same for #2, stumbled way worse again, same for #3 and #4... then I pulled off the "even harder to get off than the other side that's harder than it should be to get to" cover over the coils on the drivers side, pulled off #5, stumled way worse, replaced it, and pulled off #6, stayed the same, ok... shut her down and swap #5 and #6 coils, pull off #6 and it stumbles worse, pull off #5 and it stays the same, so it was the #6 coil (no freaking clue why #1 showed a misfire, but maybe it's going to die in the future too, I'll wait until it does, since it's way easier to get to). FREAKING FORD!!!!!!