1998 Explorer 5.0L Misfire??

[m_squared01606]

Hello All,

New to the board - Lot's of great info!!

My wife's 1998 Explorer has a mis-fire. It seems to come and go.... I know that seems odd!!

Here is what happened...... Seemed to be running fine but has 91K on it so I had a freind who is a Ford Tech do a complete tune up (plugs, wires, fuel filter, air filter, pcv) and shortly after (a day or so) I was driving it and it started to mis-fire under light acceleration.

I brought it back to him and he used his scanner and got a random mis-fire code. We thought it was bad gas.... Lots of that going on around here!!
So then he got curiois and hooked up the shop diagnosis computer and did a performance display the engine running. It showed that #3 was misfiring.....

He played with thh spark plug wire and it seemed better. However it is back again!!!

I am thinking it could be the coil?? But i don't want to throw $$ at it and not fix the problem!!

Anyone have any ideas or experiance with this??

Thanks in advance!!

Mike

 

[IAmTodd]

Bad plug, bad wire? Have you tried replacing either? Since this just started happening after you changed those, I would start there. And don't just wiggle them.

 

[410Fortune]

Correct.
Problem appeared after plugs and wires were messed with.
If the computer says its cyl 3, guess what....

Pull the plug out of 3 and check it. If it was not seated fully, gapped properly, etc it can cause this. The wire may also be broken inside or not tight enough on the plug, allowing it to arc.

It might be time for new wires.

 

[m_squared01606]

My friend the Ford Tech did remove the wire and check both ends to make sure they were crimped properly. He didn't remove the plug but as I said it comes and goes..... It can not be there for a day or be very subtle and then all of a sudden it is a huge misfire

I am recovering from back surgery otherwise I would be more active in the trouble shooting. I know the parts store Mgr very well and he said that he will give me the same wire from a new set and see if that fixes the problem.
I might try that this weekend (feeling much better!)

Just wanted to know if a coil failing can be intermittant??

Thanks for the reply's IAmTodd and 410Fortune!!

And thanks for any other ideas??

Mike

 

[performancenut]

I had almost identical issues with my 1997 5.0 XLT; it was a wire with less dielectric grease inside the boot and a carbon tract that was causing the misfire. There was a visible arc that could be seen at night with the hood light removed and while sitting idling. Removal of the carbon, wire replacement, and extra grease fixed the problem after many attempts at different fixes. If someone will take out the spark plug, do a quick compression check on that one cylinder and see what the reading will be (will give a general indication of that one cylinder and it's associated rings and valves status although comparisons of all 8 is ideal). Good luck; even one misfired cylinder can cause your engine to run rich.

Other option is to inspect coil packs. Look for cracks, etc. Could switch the two packs and see if another cylinder misfires when switched (be sure to mark your wires carefully.)

 

[410Fortune]

FYI the coil packs are really reliable, it is not often they fail, and when they do its usually a total failure.
It is usually something simple with these engine's, bad plug, wrong plug, not installed plug, arcing wire, etc....

What kind of plugs are you running?
Might double check the part number.

 

[bmacd]

how about an update ? I'm having the same Cyl #3 misfire.

-=bmacd=-

 

[m_squared01606]

It ended up being a bad wire..... Replaced it a while back. But now it is happening again! Gonna buy a set of ford wires and replace all of them!

Hope this helps!

Mike