Hey guys I have a 99 F250 with a 5.4. Recently it started missing so I replaced all the coil packs and spark plugs. It ran great the first couple times I drove it afterward but now when I start it up in the morning when its cold it idles fine for about the first 5 seconds and then it starts missing, after about 5 minutes it goes away and runs perfect for the rest of the day. Anyone have any ideas this is driving me nuts!?

 

No one has any ideas? I used Granatelli COP's and E3 spark plugs. Could it be my IAC, maf, or o2 sensors?

 

Ok I went and bought a code scanner and here are the codes it spit out.

P0351
P0353
P0354
P0355
P0356
P0302
P0305
P0306

1 I/M EVAP

 

 

First check the wiring harness to the cops. Next might want to go with motorcraft plugs and cops.

 

I`m dealing with the samething .. Mine just started yesterday. i`m hope someone will be able to help .

 

I three am having something similar---codes show misfire on Cyl #7 of the 5.4 V8. I suspected a bad #3 COP wire harness connector as this has happened before on that cylinder however previously it was the COP itself. Changed the #7 COP and problem persists so next up it changing the harness connector; NAPA part number EC259 for a cost of about $20 each.

Seems odd this happens when winter sets in---wonder if it could possibly be related or just coincidence?

Hammered I don't know which scanner you bought but I have the Actron CP9580 with something called "Code Connect" which gives the top reported fixes for any code discovered. This isn't always spot on but it does give an idea of where to begin looking. It also clears codes so you can check your repair with something more than a feeling all has gone well.

 

I changed the plugs in my 08 F250 from Motorcraft to Champion and had a misfire when it was cold. Not just engine cold I am talking 10 degrees and engine cold. Replaced with Motorcraft and no more miss. (Yet) Keeping my fingers crossed ran about 3 tanks of fuel on these new plugs and no miss. Took about 3 tanks on Champion before I noticed miss and got check engine lite. Code was random misfire on 5 and 7. Seems to run better all around. Time will tell.

 

fix .. I change the plugs to Motorcraft and replace the all the boots and springs on the cops ... Runs find now .