Bad COP?
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Mountain Pass
Joined: Jan 2011
Posts: 132
Likes: 5
From: Monroe, NC
Bad COP?
My truck is not showing a code so i'm having to go thru a process of elimination that isn't working out for me.
My symptom is a mis-fire that happens when the engine gets warm. It seems to run good at first start-up but slowly gets worse a couple miles down the road. Is this a symptom of a cop going bad? Maybe two? What is the best way to identify the bad?
My symptom is a mis-fire that happens when the engine gets warm. It seems to run good at first start-up but slowly gets worse a couple miles down the road. Is this a symptom of a cop going bad? Maybe two? What is the best way to identify the bad?
Elder User
Joined: Feb 2006
Posts: 545
Likes: 5
From: FL
It is possible for a COP malfunctioning when hot .
One simple way to find out is to buy one good COP ( Motocraft ) and swap one COP at a time until your misfire is gone (assuming only one bad COP ) .
How many miles do you have on the clock ?
when the plugs/ boots/coil springs changed last time ?
When a spark plug gap gets larger ,it takes more current to jump the electrods , then COP works harder and it gets overheated and that can cause failure .
Good luck,
One simple way to find out is to buy one good COP ( Motocraft ) and swap one COP at a time until your misfire is gone (assuming only one bad COP ) .
How many miles do you have on the clock ?
when the plugs/ boots/coil springs changed last time ?
When a spark plug gap gets larger ,it takes more current to jump the electrods , then COP works harder and it gets overheated and that can cause failure .
Good luck,
Thread Starter
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Mountain Pass
Joined: Jan 2011
Posts: 132
Likes: 5
From: Monroe, NC
I pulled and replaced all the boots when it started the problem a week ago. I cleaned the spring sockets and added plenty of diaelectric grease everywhere. I bought a new cop and now on my 4th swap out with no luck. I guess I will painstakingly go thru the rest of them over the course of the weekend. I betting that I have two that are bad and that is messing me up on the process.
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Mountain Pass
Joined: Jan 2011
Posts: 132
Likes: 5
From: Monroe, NC
I bought another new cop on the way home yesterday and this morning swapped out #7 cylinder and I think I have found the culprit. It ran smooth all the way to work. On another note, I'm pretty sure that when I swapped out #9 it ran better but still missing when hot.
I think my frustration in my process was that I had two bad cop's.
I think my frustration in my process was that I had two bad cop's.
Fleet Owner
Joined: Aug 2010
Posts: 21,253
Likes: 1,656
From: Reynoldsburg, Ohio
Backing up just a bit you say you couldn't retrieve a code with a scanner? Is the data link connector working? Did the MIL or Check Engine Now light come on?
I had a similar temperature related misfire with aftermarket COP's, overnight cold lower than 38* would cause misfire. Once engine was warmed and restarted the miss would go away, MIL still showing a fault. That's not unusual for cheaper COP's.
Another thing to check is the wiring harness connector as their locking tabs have been known to break either from old age or a heavy thumb. They can temporarily lose contact and throw a code. Replacement pigtails are available through most good parts sellers, I use NAPA EC259.
HTH
I had a similar temperature related misfire with aftermarket COP's, overnight cold lower than 38* would cause misfire. Once engine was warmed and restarted the miss would go away, MIL still showing a fault. That's not unusual for cheaper COP's.
Another thing to check is the wiring harness connector as their locking tabs have been known to break either from old age or a heavy thumb. They can temporarily lose contact and throw a code. Replacement pigtails are available through most good parts sellers, I use NAPA EC259.
HTH
Fleet Mechanic
Joined: Feb 2011
Posts: 1,812
Likes: 88
From: Thousand Oaks, CA
Our car was misfiring because of water getting on 2 cylinders causing the springs to rust. Did not throw any codes. I'm in the process of getting Torque Pro running on a Thinkpad PC to look for early signs of misfires. I've read that there has to be a certain number of misfires before a code is set.
Fleet Owner
Joined: Aug 2010
Posts: 21,253
Likes: 1,656
From: Reynoldsburg, Ohio
Most hand-held scanners like an Actron CP9580 can read the misfire counter---its typically a pending DTC but does require a threshold be reached before it will throw a cylinder-specific code.
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