Spark plug issue

[Mattsauces]

For the past year ive been experiencing hesitation and misfiring in the #4 cylinder. I didnt know what to do so i took my truck to the ford dealer. They said that once the spark plug was changed the problem was gone. Now its been 3 months since having the plug changed and the problem came back. i replaced all the spark plugs the other day and the #4 plug looked different then all the others

on the left is the #4 plug (3 months old), on the right is a plug from the other cylinders (2 years old). What might be the cause of this problem?

 

[Dan Whitaker]

Bump

 

[Cable]

I am having the exact same problem. Truck started running crappy, took it to the mechanic, he pulled the code and it was misfire on the #4 cylinder. Needed a tune up anyway so I let him replace all the plugs. 2 months later the problem came back. Took it back to the mechanic and he thinks it might be a hair-line crack in the head, right between the valves which is slowly allowing antifreeze to leak into the cylinder and foul the plug. My mechanic has worked for ford for over 20 twenty years and says hes seen this problem on a number of explorers with the ohv engine. Hope this helps.

 

[joefnh]

Mattsauces, The carbon buildup is most likely caused by excessive fuel, misfire or oil leaking into the cylinder

I would look into the following items:

1.) Spark plug wires, It's cheap to replace This would address misfire.

2.) If its the fuel injector, this is easy to replace but more expensive

3.) Oil leaking into the cylinder is harder to diagnose . Are you noticing the car burning oil? This buildup would result from a small amount oil burning and may not be noticed on the dipstick too readily.

Good luck

--Joe

 

[Mattsauces]

ya ive changed the plugs and wires, its running good for now. The issue abou the coolent getting into the system is something that me and a friend were thinking could be a problem. I guess ill just have to have alot of spare spark plugs

 

[Runnin'OnEmpty]

How does the #3 plug look?
The reason I ask, is that the same part of the coil pack fires the #3 and #4 plugs. Take a look at the 3 and 4 coil terminals, and see if there's evidence of shorting there.

I'm thinking an ignition problem here, because that plug just dosen't look bad enough to have a fouling induced misfire.

Might be a faulty coil pack.