96 XLT 5.0 V8: Coil Packs - Any Specific Suggestions?

[YamahaRick]

My 1996 Ex (220K mi) had its plugs and plug wires replaced previously. It is now experiencing a bit of misfiring under varying conditions, so I figured replacing the coil packs should be my next step.

Any specific brands I should look for?

 

[deadernie]

W I used to always run 89 octane in my 2.4 Ranger. Replace both coil packs with aftermarket ones from Napa and get constant pinging in upper RPMs and lower RPMs with load. 93 octane solves the issue but even the factory coils with over 200k miles didn't do it before they gave up. If I had the $$ at the time I would've went with Motorcraft. YMMV. My $.02.

 

[Turdle]

You could try new coil packs, but I suspect a bad wire or plug is biting you.

Bad right out of the box. Been there.

Do you have misfire codes?

 

[YamahaRick]

W I used to always run 89 octane in my 2.4 Ranger.

...

YMMV. My $.02.

Hmm; previously I had used 89 octane due to valve knock issues when under load. My Ex had been parked for seven years, and I got it out of the cobwebs just a few months ago. Had been using 87 the past few months to save a few pennies. I may try switching back to 89 to see if there is a difference.

Do you have misfire codes?

I have OBDII scanner software on my laptop, along with the proper cable. No CE Light, so I hadn't thouught about checking for codes. I'll see if my very basic tool can find anything.

 

[YamahaRick]

Do you have misfire codes?

Well, CE light came on, and received code P0304 ... cylinder 4 misfire detected. I'll examine and replace the plug, maybe use some dielectric grease on each end of that plug's wire. Hoping for a cheap fix.

 

[1998Exp]

As someone already said, plug wires are the most common culprit. The rubber insulation becomes brittle over time, and they start arcing to whatever is in the vicinity. For some reason it seems to be a bigger problem on my '98 5.0L engine than on anything else I ever had. I replaced the entire set of wires (with Motorcraft brand), just to see the problem return on one wire a few thousand miles later. You may be lucky to see the arcing in darkness, but chances are you won't.
Replace the plug first. If the misfire persists, check the wire. The best tool is an oscilloscope, but most shade tree mechanics won't have one. So just temporarily swap the wires (at both ends, of course) between two cylinders and see if the misfire follows the wire. In any case, make sure the wires are securely attached and can't touch the exhaust manifold.

Well, CE light came on, and received code P0304 ... cylinder 4 misfire detected. I'll examine and replace the plug, maybe use some dielectric grease on each end of that plug's wire. Hoping for a cheap fix.

 

[SoNic67]

Well, CE light came on, and received code P0304 ... cylinder 4 misfire detected.

Examine the wire and the heat shield. Wires have this plastic 'hooks' that keeps them from touching the hot exhaust - and those hooks sometime break.

I replaced the entire set of wires (with Motorcraft brand), just to see the problem return on one wire a few thousand miles later.

That means that the culprit is somewhere else... Or means that those Motorcraft wires are just overpriced junk.

 

[YamahaRick]

Examine the wire and the heat shield. Wires have this plastic 'hooks' that keeps them from touching the hot exhaust - and those hooks sometime break.

Bought a new plug, and headed to a friend's shop for resolution. Good spark coming out of coil pack (checked by pulling cable at coil and seeing it arc), so plug and cable were replaced. No more misfire. Mechanic suggested to get new plug wires suitable for resistance to higher temps. I have an aftermarket FoMoCo exhaust header on it, which may make the temperature in that area a bit hotter.

Regardless, I'm happy it was a very low cost resolution. I'll now look into what plug wire set to buy for complete replacement.

Thanks to all who contributed.