help with missfire

[flip_86]

i'm kinda in the middle of getting my tune worked out, truck was running a little rich, but now after a recent trip to the dyno it has a missfire during wot. It runs great all other times, 3/4 throttle it runs good, pulls hard, but wot it missfires and struggles. Has whipple 2.3 at 16psi, sbtb, ba2600, cai and tune. Fuel filter isn't very old, plugs are 3 or 4 months old. I checked on here for plug gap spec and i think i gapped them at .034, i was also running less boost at the time. I'm thinking either i have a coil dying, or maybe the spark plug gap is too big and spark is being blown out, but again this just happened recently so coil is probably more likely.

Is there any other ideas? Is there a way i can check the coils? Maybe with sct x4?

 

[Dusten]

Pull the plugs. Before you check anything else check them. Testing for a weak coil requires more software than the x4. You can ohm a coil pack but that'll only test a dead coil not a weak one

 

[flip_86]

Gap should be closer to .032? Does tbat sound right?
Thanks

 

[Dusten]

I doubt the gap is the issue. I wouldn't be surprised if you burnt a plug

 

[flip_86]

Pulled all the plugs, 2 burnt, front on the right bank and rear on the left bank, replaced all the plugs with new gapped at .033. Ran it, ran worse than before. Pulled all the plugs again, all good. Ran if again, no change. No cel

 

[RIDE THE]

Hopefully, you didn't eat up the plug bosses with that detonation.

Do you have anybody that you might know at Ford that could help you out with an IDS power balance test or retrieval of mode 6 data? This is the easiest way to determine suspect cylinders.

 

[flip_86]

Not really, i could probably get a boroscope and visually check them

 

[Dusten]

Pulled all the plugs, 2 burnt, front on the right bank and rear on the left bank, replaced all the plugs with new gapped at .033. Ran it, ran worse than before. Pulled all the plugs again, all good. Ran if again, no change. No cel

It takes a lot for these trucks to throw a misfire cel.

 

[flip_86]

The shop i dyno at can do a cylinder ballance test, if it was head damage would it have gotten worse after changing the plugs though? I guess with the burnt plugs it could have caused incomplete burn and wouldnt have been as noticeable

 

[Dusten]

The shop i dyno at can do a cylinder ballance test, if it was head damage would it have gotten worse after changing the plugs though? I guess with the burnt plugs it could have caused incomplete burn and wouldnt have been as noticeable

You answered your own question

 

[RIDE THE]

Power balance and Mode 6 data.

https://www.youtube.com/watch?v=jOFL99D_f4Q

 

[flip_86]

Did a cylinder ballance test, #1 cylinder is dead, the plug is new, swaped coil with another cylinder, tested again, #1 still dead. No oil or coolant contamination or consumption, nothing unusual in the oil seperator, sounds like a head problem

 

[flip_86]

Well, not dead, down 25 percent

 

[flip_86]

Pulled all the plugs again, something hit the spark plug in number one, the top of the piston is damaged, motor is coming out. Any tips on pulling the motor to speed things up

 

[Dusten]

It's unlikely something hit it. It's likely it was detonation.

Pulling the engine is pretty straight forward

 

[flip_86]

i recovered the a/c system, how do the lines at the back of the head seperate? just push the white tabs in?

 

[Dusten]

lines at the back of the head? The heater core lines? ya, just push the white tabs and seperate.

 

[flip_86]

These heads can be repaired to some degree right? If damage isn't too severe or cracked?

 

[Dusten]

These heads can be repaired to some degree right? If damage isn't too severe or cracked?

A machine shop can determine that, but yes. .

 

[flip_86]

Got everything undone, almost ready to pull it out, just the motor mount bolts left. Impact gun wouldnt turn them, and i'm using a newer mac gun. I had a 1/2" ratchet with a 1.5" wrench on the handle to get some extra length, i got it to turn about 1.5 turns, surprised it didn't break, i dunno what i'm gonna do next, i don't have a torch set there. I have a longer ratchet i could bring home though, or maybe take some weight off.