Intermittent miss firing on my 02 F150 5.4

[kovacs32]

So about 3 months ago I got a miss fire, turned into a dead miss, engine light started blinking so i checked codes and had a dead miss on cylinder 1, replaced coil and was fine. 2-3 weeks later same thing happens, check code and dead miss on cylinder 8, replaced that coil and was fine. Now I dont drive my F150 a whole lot, especially in the winter time due to having a company truck. about a month ago i started it up after it sat for a week, it had a dead miss and the engine light was blinking. after it warmed up the dead miss turned to a slight miss and the engine light turned solid. I eventually drove the truck for a 40 mile trip and the miss entirely went away as did the check engine light. Any idea whats causing this? I was going to replace all 8 coils but i didnt want to do that until i knew I wasnt having somthing else causing them to go bad.

thank you,
Ryan

 

[CamaroKid91Z]

My experience with those 97-03 F150s is, once on coil coils out, it seems they will sequentially go out one after another. I can't tell you how many times i've seen one go bad then another one go bad a week or two later. My suggestion is get 6 more new ones, and replace the plugs at the same time. I'm not 100% sure but I think the 02's still had the problem with the spark plugs only being threaded into the head about 3 threads and blowing out. I think im 03 they fixed that problem. pntbalgamer on here would know more since he fixes those at his machine shop.

Good Luck!

 

[kovacs32]

Thanks, I will just replace the rest of the coils. Plugs were done les than 5k miles ago so they shoud be fine

 

[pntbllgamer]

O5 was first year for 3 valve in the F150, well 04 1/2 was first year. So 97-04 1/2 had problems blowing spark plugs.

 

[CamaroKid91Z]

O5 was first year for 3 valve in the F150, well 04 1/2 was first year. So 97-04 1/2 had problems blowing spark plugs.

Well thats obvious... But I was wondering if ford fixed the threads in the head in 02 or was it 03... I know nick would know lol

 

[pntbllgamer]

They fixed them when they redesigned them
And made it a 3 valve.

 

[fastredgmc]

They fixed them when they redesigned them
And made it a 3 valve.

Yeah they fixed it so good that you cant get the plugs out of the head without them busting into pieces. Don't know how Ford could screw up on somthing so simple.

 

[chuckycaprice]

Yeah they fixed it so good that you cant get the plugs out of the head without them busting into pieces. Don't know how Ford could screw up on somthing so simple.

They keep designing it around the "Blue Oval".

 

[Justindwright]

yeah, at that age, replace all the coils and see what happens. Maybe do a good top end carbon cleaning too. They are about $15.00 each at rock auto for the standard motor products brand. Good deal if you can wait.

 

[ReiKo]

Check the plugs first to see which coil went bad...

 

[igotaneed4speed]

I would check the cat's/back pressure after you've driven it with it missing for a while. The engine light flashes when it sense a extreme rich condition that will harm the cats, typically over temps them and they melt... When I used to do spark and fuel maps on the 5.4's back in the day at ford I melted a set of cats in about half a second by accidentally fat finger the lambda input valve, sent it pig rich for seriously half a second before i reverted the value. It didn't matter how fast i changed it back because cat core temps went up over 1800* instantly and they were done for.

high back pressure can cause random cylinder misfires, typically on the same bank of the engine if its a split system.

 

[kovacs32]

I would check the cat's/back pressure after you've driven it with it missing for a while. The engine light flashes when it sense a extreme rich condition that will harm the cats, typically over temps them and they melt... When I used to do spark and fuel maps on the 5.4's back in the day at ford I melted a set of cats in about half a second by accidentally fat finger the lambda input valve, sent it pig rich for seriously half a second before i reverted the value. It didn't matter how fast i changed it back because cat core temps went up over 1800* instantly and they were done for.

high back pressure can cause random cylinder misfires, typically on the same bank of the engine if its a split system.

You know it's funny you say that because even before this started happening I been losing power and fuel mileage. How can I check the cats? I might just get them removed but I don't want an obnoxiously loud truck So I may get some high flow cats welded in

 

[igotaneed4speed]

You know it's funny you say that because even before this started happening I been losing power and fuel mileage. How can I check the cats? I might just get them removed but I don't want an obnoxiously loud truck So I may get some high flow cats welded in

Easiest way is to pull the hego's out, the ones upstream between the engine and the cat inlets. The other way is to loosen the collect/flange bolts at the manifolds. Once you do either of those it should start up, not miss and be noticeably more responsive if that's the case I'd have new cats put on, high flow aftermarket ones are typically a lot cheaper than factory replacements... In the two years I worked in a dealership doing drive-ability work and the 3 years i worked spinning dyno's for Ford I have never heard of all the coils failing at the same time, that's a crock. I think I've only seen three or four coils fail period and they were not on the same vehicle. Most of them crap out on the back two cylinders in the trucks and suv's cuz the cowl leaks water right on top of the back cylinders or the heater core/hose leaks and trashed the coil.

 

[derbydad276]

my 01 6.8L triton did the same thing 1 coil at a time over a 4 month period after the third coil went bad I just replaced all of them
with accell coils cuz they were cheaper

 

[dave89iroc]

They fixed them when they redesigned them
And made it a 3 valve.

No, they went to more threads in 02 IIRC

 

[1BadSn95]

O5 was first year for 3 valve in the F150, well 04 1/2 was first year. So 97-04 1/2 had problems blowing spark plugs.

Well thats obvious... But I was wondering if ford fixed the threads in the head in 02 or was it 03... I know nick would know lol

They fixed them when they redesigned them
And made it a 3 valve.

We had a 2002 F250 with a 5.4L. Blew plugs out like its job around the end of 2003. Took it to the dealer for this known problem at the time they warrantied the heads with the "updated" heads that i believe have 6 or 8 threads. they told us the updated heads came out in 2004 for all the 2v's. Obviously the 3v was the next change in 2005. Surburban Ford gave us the option of new heads installed for free or a entire new motor for 1600 bucks installed. We took the motor.

Yeah they fixed it so good that you cant get the plugs out of the head without them busting into pieces. Don't know how Ford could screw up on somthing so simple.

No shit. Not to mention you need a special tool to gap them and they plugs arent cheap either.

No, they went to more threads in 02 IIRC

I think it was 04 then went to the 3v in 05

 

[SVT32VDOHC]

I had a bad coil on 97 F-150. I'm pretty sure I got lucky and the one I touched gave me a shock and I changed it. No problems after that. I had the misfire after driving down 94 in a heavy snow storm.