Intermittent Hard Misfire on #8

[BarryCarey]

Hey All,

I had an issue popup last week that I haven't been able to track down.

I'm getting an intermittent hard misfire on #8 (Flashing CEL). When it's not flashing there is a small shake and misfire count keeps rising (viewed via scanner)

I put a new COP on and there's still a slight misfire. No flashing CEL yet (but it was random before) but MS count creeps up.

Plugs are all new Motocraft.

No cracks in wires coming out of harness. I also cleaned the contacts.

I believe the only other thing it could be is an injector issue or a wire issue in the harness.

Does anyone have any advise for tracing down the cause?

 

[Number4]

I think the DOHC engines have a tendency to burn up the exhaust valve due to bad coolant circulation through the heads, but I don't know that this is a SOHC issue.

Still something to check out.

 

[anthonymtz]

Hey All,

I had an issue popup last week that I haven't been able to track down.

I'm getting an intermittent hard misfire on [URL=http://www.explorerforum.com/forums/usertag.php?do=list&action=hash&hash=8]#8 [/URL] (Flashing CEL). When it's not flashing there is a small shake and misfire count keeps rising (viewed via scanner)

I put a new COP on and there's still a slight misfire. No flashing CEL yet (but it was random before) but MS count creeps up.

Plugs are all new Motocraft.

No cracks in wires coming out of harness. I also cleaned the contacts.

I believe the only other thing it could be is an injector issue or a wire issue in the harness.

Does anyone have any advise for tracing down the cause?

I has this exact same issue, I was on the freeway and I was doing about 60mph, so with a empty freeway and my curiosity of how the 4.6 did WOT I punche it, I got to 100mph fairly quick but all of a sudden my CEL was flashing, to make a small story short I had a misfire in cly #8 so i got new plugs for it, well when I went to remove the coil packs there was a puddle of water in it, maybe 2 oz at most, so I got my shop vacuum and sucked it out replaced the plugs, cleaned the coils and ect. Not sure how the water got in there but I have not had a problem ever since, I firstly though it was coolant but it was just plain old water, it runs strong now! Maybe check and make sure water didn't make its way in there! Good luck