Coil Packs

[A1cntrler]

Right now on '07 V8 I have had an issue under load (hard acceleration) where only if I have the window down and can hear the exhaust it sounds like it is missing. Still pulls normal though. Also in top gear if the cruise control kicks on slightly for an incline or if I apply gentle pressure to the pedal, it feels like the truck is going over bumps, but the road is smooth. At first I thought it was the trans looking for a gear, as once it downshifts it runs smooth/great.



It starts up quick and always idle smooth and quiet. The problem does not exist until the engine has warmed up for the first trip of the day. I think once the coils get heated up, they start having the problem.



A little more research and I discovered others with F150's with the 4.6 and the 5.4 motors having the exact same issue. They all traced it down to the coil packs. Yep, there are 8 of them and there are no codes thrown by it, but replacing them supposedly fixes it. At $40 a pc from Rockauto for Motorcraft ones, they don't recommend doing that. People asked about replacing them with packs from MSD or Accell and again those are pricey as well (although cheaper than Motorcraft). The way to go from the guys on the F150 boards I have been reading are ones from Ebay from a guy called Uneeksupply (I think that was how he spelled it) and they were under 100 bucks for all 8.



Apparently once one pack goes they all start to in a short period of time.



I haven't done mine yet (waiting fro the funds) but I only drive it a few miles a day to school and back.



Anyone else have issues with the packs yet in their ST's? I just passed 84k miles on it.

 

[scott degroot]

It is a myth that once one coil pack goes bad the rest start to go bad. Even though there is no check engine light on the misfiring cylinder can be pinpointed with a scanner by observing what is called mode 6 data. Any mechanic that is worth anything knows how valuable this data is on Fords with misfire issues. What we commonly do when we suspect a bad coil is to determine which coil it is and then move it to another cylinder, drive the vehicle and then look at the mode 6 data again and see if the misfiring cylinder moved to the cylinder that we swapped the coil to. Another thing to look for after the cylinder has been determined is to make sure that the spark plug hasn't dveloped a slight crack and that the coil boot hasn't developed a burn spot in it. If so just replace the coil boot along with the spark plug.



Once you find the offending coil and by looking at your mileage I suggest replacing all the spark plugs. Letting them go any longer is just asking for trouble as they only get harder to remove. I also recommend that when you replace the spark plugs that you replace all the coil boots as well. They are about $5 each.

 

[Supercharged SVT]

i would look at Plugs too - all it takes is is a little junk on the plug and it will misfire.

 

[Scott Tanner]

+1 on plugs... My coil packs and wires on my trac have 216k on them... under load, a worn plug will miss like that... in the ignition system, the weakest link will fail first and cause a misfire. the plugs are the only "wear" item in the system, and it can't hurt to change them anyways.

 

[Vic Sorlie]

STanner, your 2002 V6 doesn't have coil packs. If you've got 216K on plug wires, I'd say most members here would advise replacement - how many miles on your plugs?

 

[Scott Tanner]

not coil on plug, but the other type with the 6 terminals...



100k on plugs, and they are starting to cause a buck. they are getting replaced real soon...

 

[Todd Z]

I replaced ( and sell) mine with the SOS ( sultans of spark) high output ones from Perfomance distributors....



36K miles and I No problems and I love them !!



Todd Z