well, at least i think its a misfire, only happens from about 1500 to 2500 rpm then its done. im guessing a COP since it did this before my plug and COP change. no engine codes, so i dont know which one it is to replace it(i have some extras from when i did the plug and COP change)........anyone have a way to find out which one it is?

thanks
Adam M

 

is it only misfiring under load(while driving)? or will it misfire in park and holding the rpm up? what brand plugs? mileage? you can go onto ebay and type dg508 in the search bar and you can buy a full set of 8 coils from global or uneek for 75 bucks. or you can get the v10 pack for 95 bucks and have 2 spare coils. and dont forget to use dielectric grease.

to find out which cylinder is misfiring i always either unplugged them one at a time to see which one doesnt make a difference or use a misfire code.

 

ya, its only misfiring while driving, idle is smooth....i did the full spark plug and COP replacement job about 15 k ago(motorcraft plugs and the dg508's, and actuallygot the v-10 pack for issues just like this), now im finally getting to finish my tune up.... i just did the full throttle body cleaning (took the tb and elbow off cleaned with carb cleaner, and had some coolant squirt out of one of the lines on the elbow until i got it capped off)and im wondering if the miss could be from some of the coolant getting down on one of the cop's?

 

its very possible. another thing to look at as far as coolant goes is the heater core hoses. the clamps dont last forever and they let a little bit of water leak out and it'll drip onto the coils. just something to look at. did you use dielectric grease when you did the coils and plugs?

 

ill check the hoses out, and i did use dielectric grease.... probably not enough, buut i did use it.

 

That Sucks, If there's no other evidence, - I might try to stick a gun attachment to the air hose and blow into the back cylinders (3 and 4) to see if coolant blows back at me lol. That's a last resort I guess. I would push the engine when she's acting up or hold it there, - at where-ever load she's misfiring under. The monitor might catch it then, try it several times if you have to. It can be a PITA finding the bad one when the monitor isn't seeing it.

Purchasing your own scan tool would be a good idea. Around 70 bucks. Disconnecting the harness won't work in this case.

It might be worth just taking it to Ford for a stress test. That will reveal a bad one. Call for prices on the stress test.

 

didnt do it at all today, but idle seems to be a little rough, no codes on the scantool. i know it will come back, so im thinking about replacing all 8 cops again, but i REALLY dont want to from doing it 15k miles ago......or just swapping out the back 2 on the pass side bank with my extra cops and seein if that gets rid of it....

 

I would start in front with the two new ones. NOT the rear lol.

That way, you can eliminate 1,2,5 and 6 inside of 45 minutes from being the culprits. The front four are easy, you could knock those out fast.

Change 1 & 2. Still missing? Yes, - Throw 1 & 2 into the 4 & 5 spot and so on.

That's the cheapest and smart way to do this. You already purchased the 10 pack, now use that to your advantage. Hell man , Nobody WANTS to change coils, regardless of how old they are.

Good Luck. - (cuz you'll be needin a little ( : )

 

well with it bein rainy yesterday it started doin it again... and after 3 or 4 WOT runs.... popped a code (is it wierd to like seeing a code?) and it was cyl #3.... not bad to change out and its not doin it anymore........ pretty stoked about it too!

 

well with it bein rainy yesterday it started doin it again... and after 3 or 4 WOT runs.... popped a code (is it wierd to like seeing a code?) and it was cyl #3.... not bad to change out and its not doin it anymore........ pretty stoked about it too!

 

I am glad to see I am not alone. 84,000 on my 2001 Supercrew cab 4x4 with 5.4 L engine. Misses a little at idle and more at 1500-2000 rpm. Changed 1,2,5and6, still have miss the old plugs were worn but not wet or oiled but had some hard white deposits. Going to let a younger Ford mechanic do the other rear plugs.

Did you folks notice the bad cylinder spark plug showing signs of buildup which was different then the other plugs removed?

I think I will change the fuel filter also because it has never been done.

Does anyone know how much fuel drops out, and how long you need to wait for the fuel system to reduce pressure in order to remove the fuel filter???

Wish me luck on finding the missing cylinder or cylinders. It is amazing how it seems to shake the truck when is starts missing under load.

 

[QUOTE=spwjones;3792319]
I think I will change the fuel filter also because it has never been done.

Does anyone know how much fuel drops out, and how long you need to wait for the fuel system to reduce pressure in order to remove the fuel filter???


not much fuel leaks out, and somewhere there is suppose to be a release valve but idk where it is, so i just take mine off without releaving the pressure, its not that bad unless you dont like smellin like gas for a day

 

The pressure release valve is on the fuel rails attached to the injectors. There is a schrader valve with a black plastic cap on the fuel rail. All you have to do is remove the cap, and press down the pin in the center of the valve (its similar to a tire air valve) and the pressure is released.

Also on the misfire, I had a mechanic tell me once that 97-03 5.4's are notorious for killing the #3 COP due to the coolant lines that run over it leaking onto it. Not sure if this is true, but I had that same #3 COP die on mine recently as well.