fordguy2100

Been having a check engine light on and the original code is P0304 which is a misfire on cylinder 4. I've replace the spark plugs (OEM) and replaced 3 coil packs (cylinder 4, and 2 others that needed replaced). Spoke with a guy who thinks I have a leak in the head gasket but I'm not so sure I believe him (wasn't there when he tested it under pressure). Does anyone have any suggestions or help with this problem? Thanks in advance.

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fordguy2100

anyone have any thoughts?

RLXXI

The heater hose that sits right above that cylinder is a known cause for misfire, it will leak coolant onto the coil and short it.

Look at the top of it and see if it has a dried residue that might be greenish if you have maintained your cooling system.

Pull the cop out, blow out any standing liquid with compressed air and replace that cop, don't care how new it is, once it gets hit with the coolant it's garbage.

Tighten that hose clamp or replace the hose completely if it has the quick disconnect end.

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fordguy2100

So I've had the injectors cleaned (was a longshot but didn't fix the issue, now I have a super long crank when I try to start the truck, but it's intermittent and is a random issue, other than that the truck runs good once it gets going and now my misfire is less often and not as noticeable... And recommendations on either of these issues?

Also coil pack was clean, hasn't had any fluid on it

fordguy2100

Still no thoughts from anyone? I'm really hoping I can do this myself and not drop it off at a garage or dealership

Jackedup00

Do a compression test and see what it shows. You can get a gauge from part stores,just leave them a deposit for it and take it back when you're done

fordguy2100

Finally got around to messing with it, used some of the head gasket sealant from autozone and so far no troubles... Hopefully this is the end of that problem

fordguy2100

Thanks, I did a compression test and it failed, hopefully that sealant will hold up

Blove

Today my truck started to shuddering real bad when I try to accelerate it on the road, I felt as if the motor wanted to jump up out of it the way it was doing right, when I got home and cut it off, I looked in the back seat and got my code scanned to see if it would show any codes which it did right, come to find out that it is cylinder 4 misfiring, when I took out the spark plug boot and the spark plug itself, each one was wet right, I smelled the stuff on it, smelled like anti-freeze, even though it was brown looking color on the plug and boot. I'll be getting a shop rag and try to put down in the deep well part where the plug and sire go in at on my 4.6 motor in my 97 F-150. I hate that the plugs go down deeply, I don't like that it is way in the back on the passenger side, but I do not have a problem getting in to get it out, I got me a magnetic 5/8 spark plug socket that'll strongly hold the spark plug on when it is loosen t come out that deep well hole, it does good too. I could not hardly drive it today, no. last year I put in some blown head gasket sealant stuff right, it is seeming to real good, it suppose to be some permanent sealer like it says on the bottle, it has been 5 month that stuff is doing real good as I have been able to put some miles on the truck with the help of that stuff.

Harleynana

OK. I am having similar issue with my 97 F150. V8 5.6. Almost 2 years ago engine seized and had MY engine rebuilt. Ever since I got the truck back its been misfiring and running real rough. I went through the plugs, wires and coil pack. Found anti-freeze in more than 1 well. Dried them up, changed the plugs, wires and one of coil packs. Still hasn't run smoothly even changing those parts. I supposedly had someone fix or replace the head gaskets 2 more times. Its doing it again really bad and find the 7 and 8 had anti-freeze in the wells again. Again mechanic says head gasket. Well I have had to pay to have the same issue repaired or replaced 3 times, now going on the 4th time. is it safe to say its an ongoing issue with F150's? What is the name of this sealant I keep hearing about?