I keep getting a #6 cylinder miss fire that I can't figure out.
1998 4.2L 192K miles.
Replaced wires, plugs, coil pack yet the problem is still there. Any ideas?

 

have you checked the codes again
the problem may be the injector.
maybe

 

I'll check again, but they have came back the same code. Nothing about injectors. But at 192+ miles I bet they are gunked up.

 

Did you disconnect BOTH sides of the battery before you worked on it ? Did you reconnect Positive first when you rebooted the PCM?

Is it misfiring or r u just getting the check E light and the code ?

 

I took off the negative only which cleared the codes.

I am getting a check engine light with code. It usually happens at low speed like when I am in a 25 MPH zone. Another time it happens is when I am coasting down this long hill where I livewhen the engine is just getting up to temp.

I used a stethoscope and heard the injector chattering away so it is a least doing something.

 

Injector plugged, large intake leak at the port runner for that cylinder, valve problem.
Use a vaccum gage to look at the action, then go with what the gage is suggesting.
It's an art, reading gage action for cylinder problems so get the info first and look at it.
It's found in older shop manuels, pictures and all, in the library.

 

If it's an earlier '98, you may have a manifold gasket getting ready to go.

 

So when you pulled the plug, what did it tell when you read it?

Did it look like it had just come out of the box because it had been steam cleaned by coolant? I know you didn't just toss it! Either way, the crank position sensor is getting a touch of a misfire and you haven't dug down deep enough for diagnosis.

What's with pulling battery cables to clear codes? You all like to work too much. Just pulling the fuse to the PCM in the underhood fuse box will do the same thing...

 

Okay , so it's not missing ? - just want to be clear

Your just getting a check engine light , but it's running fine right?

 

Yes just check engine light. The engine runs smooth. The only problem this truck has given me, EVER, is a bad alternator. Thats all. Well, a tranny rear seal leak, but this has been a perfect vehicle for all 192+ miles. That is why this is so frustrating. I might just take it to Ford and have them put it on the scope.

 

You have to do carefull analysis because the ignition monitor is detecting that cylinder as not contributing the same amount as the other 5 cylinders, within narrow limits.
It does this by measuring the rotation time of each cylinder and compairing to a table of normalized averages for all cylinders of a fault free operation.
The crank sensor signal is used for many things beside just to begin spark control.