TheQuicksilver

Question, got a code thrown for a cylinder 8 misfire. I've been running rough, and was expected it soon, and was just waiting for the problem to be bad enough for the ECU to throw a code. My understanding is that the '03 4.6 V8 was coil-over-plugs. I used to have a Lincoln LS that had coil packs, and they started going bad, and I replaced them as they went out. This was a real PITA, and I started just taking it in to have them swapped - but that was mostly because that motor is shoehorned into the LS, and they were a nightmare to get at towards the back. I'm thinking my F150 is much more manageable and I'll try it myself this time before caving to a shop on it.

In retrospect, I sorta wish I'd done them all at once on my LS, since one going is a sign that others probably aren't far behind. I'm curious what others think about this. If you have to get in there, is the replacement process simple enough that you'd just do the bad one, or would you go ahead and do all of them on one side while you're in there?

And in a similar fashion, if you're swapping the coil, would you just go ahead and drop in a new plug while you've got things opened up? Seems like sort of a waste to go to all that work and not swap the plug too, but maybe I'm being overly cautious.

Jbrew

How many miles on the coils?

How many miles on the plugs ?

Owners manual ?

Answer these, then answering you will be much easier.

TheQuicksilver

Unknown on the first two. I bought the truck with 108K, at 117K now. I'm assuming they've never been changed though.

And yes, I have the owner's manual.

Jbrew

Yea, update everything. Just make absolutely sure you get the CORRECT brand of parts.

I'd go through it at those miles. It's a good idea to catch the O2's as well.

Manuellabour247

At that mileage, it's definitely peace of mind knowing that you have a fresh start on them. If it were me, I'd replace the COPs and plugs. Do not assume that they are gapped correctly. Get a proper gauge and check them before you install them. Might just want to get a basic tune up kit and do everything at once so you limit your downtime on the truck. Oil, filters, etc. Since you're unsure on the maintenance history, this would be a good starting place.

TheQuicksilver

Actually, I just went through all the oil and filters and basics like that a couple weeks ago. In fact, I have to replace the oil dipstick tube while I'm in there too, because when I went to check the oil, I discovered the tube had rusted and broken off. Just had all the front ball joints replaced, too. Been on a maintenance spree, as I'm almost paid off, and would like to get a few more years out of it payment free before getting something newer. This issue with the coil pack was just sort of coincidental.

Mike Gross

As long as you're there, just do them all,cops and plugs. Some people never have problems with their cops, but its recommended maintainence at 100k. You'll feel better about it.

Ive actually been very lucky with knockoff brand Cops. For a set of 8, it was less than a single motorcraft part. Worth a try and no problems in 30k.

You're almost better off buying the coils and installing them, then having your plugs done in a reputable shop. If you're confident doing them, great, but that can go really well or horribly wrong. At Least that way if you spit a plug its the shops fault. This is about the time that starts happening.

4x4dave

Have fun with the dipstick tube. That sucker is tough to get off.