Ok, so I've read alot of old posts from 2010 and prior about things like this but I haven't seen anything quite like what I'm dealing with. When it's about 50 degrees or below the first crank in the morning, it usually runs like crap. I'll drive about a mile down the road and when I can see the temperature gauge rising to normal, I stopped, put it in park and then I hear everything smooth out. Then I'm good to go. When I pull up the codes it shows numerous of 300 codes for coil pack misfires. It's about six of them. When the truck is warmed up after a while I can cut it off and run codes again and it's usually just one. It is the p0351. I know the IAC is a possibility but the COP codes worries me. I heard that a common cause of this is a body to engine ground but I couldn't find anything. Maybe I don't know exactly where to look. What should I do doing?

 

How many miles on the engine, spark plugs, and coils? What brand plugs and coils are in it? Was dielectric grease used at the last plug change, and could it have possibly been overused?

On general principles, I think I'd clean the MAF and IAC.

 

It's 220k miles. I cleaned the MAF. The coil packs and plugs are new. I changed these, thinking it was gonna fixed the problem. The packs are Accel. The plugs were pre-gapped to specs

 

Did you use MOTORCRAFT plugs, torqued to 28 ft/lb? Accel coils may have been a mistake, they don't have a good track record in these engines. I recommend only Motorcraft, Denso, or Delphi. Did you use a small amount of dielectric grease in the boots, keeping it off the spring contacts?

 

Yes, as glc said, use MC plugs and coils.

 

MC plugs were used. I had it done at a shop. I cannot say they used grease but one would assume they did what they're were suppose to do. 6 misfires out of 8 plugs. Prior to changing them and after. I'd like to think a little out of the box on this one. Is there anything else other than the obvious that could cause this? Engine to body ground?

 

I really believe it's the coils.

 

Nah. I don't think that. I'm sure your knowledge exceeds mine but with this truck and it's history, I can tell you that the packs that I took out was MC and replaced with cheap ones. What's the odds that new cops doesn't improve anything? I've read so much stuff about how people go through these coil packs like candy. 1 MC set after another. I just thought someone could shine some light as to what kind of short or ground can cause this, regardless of the type of packs. Sorry!

 

I can understand where your coming from, lots of frustration. Really doubt there is chassis/frame ground problem....but stranger things can happen.

Was it missing or misfiring prior to changing the spark plugs and COP's?

Do you still have the old COP's?? IF so, can you swap in one of the old COPs to a "known cylinder" that is showing a misfire currently. (or just get 1 new MC COP or brand that was previously suggested by GLC , post #4. )

Then rescan for codes.... IF....things improve....Then that proves that the "new" cops are not up to the task. Quality of aftermarket stuff has degraded tremendously.

Most of the stories of misfires from "new installed" COPs and spark plugs ....probably stem from 2 things. 1) going to aftermarket COPS after reading advertising hype of their products, when in reality they don't perform any better then OEM. or folks get sticker shock & go get the cheapest things they can find. 2) improper installation of products or not doing a complete job.

NOT saying this is your situation.
Incomplete job meaning; leaving the rear most spark plugs not changed because they are a pain to get to. Or, getting new COP's and spark plugs and not changing the Boots and springs with them. and over use of the Dielectric grease .

Sometimes ya just gotta go back and redo things , inspite of trying to do right the 1st time.