Testing Ignition Coil

[Joey82]

Hi All,
Just started a thread about an AC issue and since I went ahead and did stuff related to the intake, I was going to swap the spark plugs too. While I'm at it, I was considering the Coils as well, (this is the 4.6 Coils-on-Plug). Given the price for all 8 cylinders with genuine Motorcraft, I don't want to risk throwing money away on something that's not broke. Is there a way I can bench test each of these out of the vehicle with a regular old multimeter? I've seen some videos but it seems like they related to 3 and 4 pin styles compared to this two pin style. No clue what I'm doing and no plan but pretty good liquid courage and curiosity if I just new what I'm looking for.
TIA!

 

[94Eddie]

Are any misfire codes being tripped? I wouldn't replace the coils on a hunch as there are good odds that they are good. Or just one, maybe two, are bad. Maybe reading the misfire rates for the cylinders can shed some light on whether a coil is a problem.

 

[Joey82]

Are any misfire codes being tripped? I wouldn't replace the coils on a hunch as there are good odds that they are good. Or just one, maybe two, are bad. Maybe reading the misfire rates for the cylinders can shed some light on whether a coil is a problem.

Thanks for the reply! And I should've said, but no codes or anything like that. I'm more just trying to figure out if they're aging (second set about 10 years ago. Accel brand). When I first swapped them, one original was definitely bad and throwing a code. When I swapped that one, it was like the engine woke up. When I swapped the remaining... Nothing. No big improvement but happy for the peace of mind. Years later now, I'm just trying to see if I should stay in front of things and go back to Motorcraft since I'm doing the spark plugs (again, just preventive maintenance at 110k). If these things were cheaper, I wouldn't give it a second thought, but $$$ for something that might be perfectly good is tough to justify.

 

[94Eddie]

How many miles are on the plugs?

 

[Joey82]

Mileage-wise, not many at all. Maybe 20k. And immediately, you think I'm crazy. I get it. But years, it's probably been 6-7.
The original plugs and coils went around 75k. When I got the truck, it developed a misfire. I believe it was the 8th coil that had gone bad. Swapped that and immediate gratification. Within a year, I swapped the plugs and other coils to have a baseline. But maybe a few years, and I couldn't ignore a ticking. Kind of like an exhaust leak that wouldn't go away. Beat my head against the wall until I found an old receipt. Then I noticed the plugs they gave me were for an expedition! Swapped them for the right part number (all Motorcraft) and the ticking went away. Not much in feedback or anything though.

Fast forward to now and I have another set of plugs I was going to toss in. And despite the mileage on the coils, I'm wondering if I should throw that in the mix as well. I try to drain/swap parts every five years on all my stuff, but these coils are just a bit too pricey to call "routine". If there were some validation with a multimeter or something, I'd feel justified. But literally throwing away a new car payment for no reason makes me sick.

 

[Bazz270]

Your PCM is a bench

No misfires simply means that a coils are good.
You have no reason to replace the coils.

 

[94Eddie]

Mileage-wise, not many at all. Maybe 20k. And immediately, you think I'm crazy. I get it. But years, it's probably been 6-7.
The original plugs and coils went around 75k. When I got the truck, it developed a misfire. I believe it was the 8th coil that had gone bad. Swapped that and immediate gratification. Within a year, I swapped the plugs and other coils to have a baseline. But maybe a few years, and I couldn't ignore a ticking. Kind of like an exhaust leak that wouldn't go away. Beat my head against the wall until I found an old receipt. Then I noticed the plugs they gave me were for an expedition! Swapped them for the right part number (all Motorcraft) and the ticking went away. Not much in feedback or anything though.

Fast forward to now and I have another set of plugs I was going to toss in. And despite the mileage on the coils, I'm wondering if I should throw that in the mix as well. I try to drain/swap parts every five years on all my stuff, but these coils are just a bit too pricey to call "routine". If there were some validation with a multimeter or something, I'd feel justified. But literally throwing away a new car payment for no reason makes me sick.

I changed my plugs at 120k miles and found the center electrodes had worn so much the gap was twice what is spec'ed. This was causing a hard start issue and slight misfires. Changing to new plugs fixed the hard start problem and the misfires. If you had a lot of miles on them it might be the source of your problem. Since you used Motorcraft OEM plugs then I don't think they need changed. It is miles that wear out plugs and not time. Sometimes non Ford plugs can cause issues.

Since you mentioned that the #8 coil went bad there is a problem with the 4th gen V8s letting water drain straight into the #8 spark plug well. This can cause misfires and coil to plug connection issues. The video below deals with this problem. It is worth checking out, IMO.

 

[Joey82]

Bazz, that made me laugh! But I think you have a point. And thank you Eddie! We just had terrible storms the other day. Really wish I checked after. I have the plugs and even if it's been nothing mileage-wise, they're paid for and simple enough to do. I'm going to pass on the coils but I'm going to take the plugs out in order and examine each to see if there's any cause for alarm. I know the condition of the plugs can tell trained mechanics what's going on. My concern now is degradation related to the coil boots themselves if they're getting showered like that. Still, no misfires (knock on wood) but never hurts to stay in front of these things.
Thank you guys!

 

[Bazz270]

You can replace the boots only (use the oems).the coil should be seated with press fit like condition.

I mean after the coil retaining bolt released,you should feel some kind of medium effort to take the coil out of the engine.

If the coil slides out of the engine without any effort ,replace the boot.