I have a misfire and I think it may be a COP. I had a miss on the same cylinder years ago and I bought an aftermarket COP to try to fix it...then like a dummy I threw away my stocker after staring at it on my shelf forever. A buddy of mine who sold his truck gave me about 4-5 of his old COP's but I don't want to spend forever putting them on and waiting for a CEL...or switching mine around and checking for the code to follow. It would be ideal if I could just see if they were good/bad and throw one on to replace the aftermarket coil.

 

Bench testing will only show you if it's completely dead. They need to be load tested on the engine.

Swapping them around is really the easiest thing to do. You also need to pull the spark plug and look at it.

How many miles on the plugs?

 

Not really (easily). You can make resistance checks that are close to useless but easy. After that, it gets a lot more difficult.

You're best to simply install the coil in the easiest cylinder to reach and see whether or not it introduces a misfiring symptom.

 

You can, but it's expensive. Not to mention most shops don't have the equipment or knowledge.

Coils are PWM driven, and with that you need a oscilloscope to see the oscillations

With that being said, you still can't get the same experience as if you had it on the engine itself. Things such as heat, humidity, vibration, etc will all contribute, something that a bench test cannot.

Coils are considered consumable items. Same goes for injectors and plugs.

 

Thanks for the responses...maybe I'll just buy a replacemet Motorcraft one and call it good.

 

Denso makes motorcraft cops supposedly. see rockauto for prices

 

Motorcraft, Denso, or Delphi. All OEM quality.

How many miles are on the spark plugs? Pull the plug and look for cracks, damage, and fouling.

 

If you want to actually identify which cylinder is the issue, use a scan tool (or equivalent) to look at the misfire counters in Mode $06. That's the fastest way to pinpoint the hole when the misfire isn't severe enough to set a fault code.

 

I'd say there are only 30-35k on the new plugs...changed at either 80 or 85k, can't remember. I changed 'em.

I have a scan tool, it's how I knew it's the cylinder with the new coil.

I think my plan will be to change the plug to a new one, and swap the coil with another cylinder at the same time.

 

To review; the engine control system does all the coil testing you need.
There are only three possible faults a coil can have.
1. An open primary or secondary.
2 a Short.
3. Shorted turns in the winding that may or may not be temperature sensitive.
.
System detects # 1 with either a code 030x or a 035x. These are two different failure types
Shorted turns shows up in a different way as lower output voltage that causes misfires under certain conditions. This misfire does not normally set any codes but must be looked for with a Scanner observing misfire history in program. The memory location has no ability to set code.
This type fault is not considered a hard fault because it comes and goes per the condition but still has a record in memory.
The only test for this fault might be an Inductance test compared to a known good coil with consideration for tolerance but still would not pick out a temperature related issue.
.
Bottom line is use a Scanner to look, or to trap the cylinder with freeze frame data when it occurs.
Good luck.

 

Just a quick update:

I bought a new plug and swapped it into the cylinder that threw a code.

Then I took that coil and swapped it with the front one so it would be easier to get to if it threw another code.

So far so good.