I have a 2000 F150 with the 5.4. have been chasing cylinder misfires for around 6 months or so. I would change a coil it would go away. Come back. Change another so on and so forth. Then it got to the point where the misfire kept coming back to the same cylinder. Cylinder number 6 one day i pulled the coil only to find coolant in the spark plug hole. Checked the others and found coolant in cylinders 2,3,and 5. Someone told me to change the intake maniflod that the crossover crack and then leaks coolant which ends up in the plug holes. So after eight hours of work, one new intake manifold,new valve cover gaskets, and one new coil in cylinder two. I still have the misfire. Any ideas. Anyone. Your help would be greatly appreciated.

 

typical issue with the leaky elbow...


so did you bother changing the plugs???

 

Plugs are new about 3000 miles ago. Plugs are motorcraft plugs originally I replaced with a set of Bosch platinum and found out they didn't work and then had to go through the trouble of doing it again

 

And what brand of cop's?

Did you blow/clean all the fluid from the plug wells? I would have pulled the plugs to see what they look like. Any corrosion would foul the connection from the cop spring/boot to the plug. Same for the cop on those cylinders with coolant in the wells. The springs will need to be cleaned and boots dried out before you reinstall them. Make sure your battery is disconnected while doing any of that. Then see if it comes back. Did the CEL come back or is it "still on" and can you actually feel the misfire? Any other maintenance? Fuel filter, clean the TB while it was off, MAF sensor.... etc

 

While doing the intake. Plugs were pulled. Cleaned. Coil springs were all cleaned. Changed the cylinder 2 two days after intake work. Misfire got better but still there. As far as coil brand. They are duralast from auto zone. Had engine lights cleared after coil change. Yesterday. Came back on today. After around 20 mins of driving haven't been able to check them again yet. Codes before cleared were misfires in cylinders 5 & 6

 

how old are the injectors / fuel filter?

 

Injectors are stock. Fuel filter not sure.

 

I did COP/Motorcraft plug change last summer and constantly got cyl. 3 misfire. After swapping out #3 with several replaced coils (thinking I didn't have them seated properly)... it turned out to be a defective new plug (Motorcraft). I am now running (just fine) on 7 new plugs n 1 old one.

Did you use dielectric grease on the COP tips?

 

Yes I used the grease on the tips

 

Fuel filter is probably due if you don't remember. Once a year is good practice. Especially with fuel grades not so good anymore and all the lovely ethanol. So for $10 you can at least change it out. I would put those duralast cop's in question. Not sure of the reviews on them but don't know many people using them. Must be a reason. If your confident the plug or cop is doing fine, try swapping injectors from the cylinder that is misfiring to a known good one. Clear the CEL and wait to see if it moves or comes back to the original cylinder.

 

I'm game for anything at this point!

 

Fuel filter first, Duralast COPs are crap.. Higher resistance than oem ford....

 

Junk. Get a complete set of 8 DG508's on Ebay from Uneek Supply or Global Automotive for about 80 bucks.

 

I'd get the 10 pack -

http://cgi.ebay.com/ebaymotors/IGNIT...Q5fAccessories

Plus a 12 of Labatts Blue and have at it.