Strange question regarding COPs
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New User
Joined: Jul 2008
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Strange question regarding COPs
I'm having trouble determining if I have a bad COP. My CEL never comes on when my truck is missing.
A friend suggested using an infrared thermometer (I have a very expensive for work that has a very tight radius and is extremely accurate) on the COPs.
The badone should be significantly hotter than the others.
Anyone agree or disagree with this?
BTW - I have a 1999 F250 Super Duty 4x4 w/ 5.4 Triton
A friend suggested using an infrared thermometer (I have a very expensive for work that has a very tight radius and is extremely accurate) on the COPs.
The badone should be significantly hotter than the others.
Anyone agree or disagree with this?
BTW - I have a 1999 F250 Super Duty 4x4 w/ 5.4 Triton
Sit. Stay.
Joined: Oct 2001
Posts: 18,308
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From: Washington State
I can neither confirm nor deny that method of testing will work.
However, I know of an easier way.
Start with the rear passenger COP and swap it out with a known good you buy from the auto parts store. Play round-robin until your miss is gone. #4 is usually the culprit. Mainly because it is the hardest to get to. 
However, I know of an easier way.
Start with the rear passenger COP and swap it out with a known good you buy from the auto parts store.
Play round-robin until your miss is gone. #4 is usually the culprit. Mainly because it is the hardest to get to.
Post Fiend
Joined: May 2006
Posts: 10,007
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From: Central Florida
I think you'd be better off checking the manifold's temp at the head. The missing cylinder will be colder than the rest. The wires that go the coil are so small that I can't imagine even an completely closed short could heat them up enough to register higher then the rest through the casing.
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New User
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I haven't had AZ test it yet....but I did call them and they said that without a CEL their tester would pick anything up??
Sit. Stay.
Joined: Oct 2001
Posts: 18,308
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From: Washington State
This was posted the other day.
Tester Coil on Plug Quick Probe
Should make find the offending coil easier, I suppose. It's $86, though. Still, not a bad tool to have if you do you own work on your truck.
Tester Coil on Plug Quick Probe
Should make find the offending coil easier, I suppose. It's $86, though. Still, not a bad tool to have if you do you own work on your truck.
Elder User
Joined: May 2008
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OBD1 systems, such as the one used on the truck in question, will not store a code for misfiring coils unless it totally fails. The "hit and miss" procedure is about the only way to find the bad one until it totally fails.
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Tuned
Joined: Dec 2007
Posts: 338
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From: Hooterville, WI
What AZ uses amounts to a cheap pocket tester. They couldn't read mine, I doubt they'll be able to read yours. I was able to find it though using my dad's (quite expensive) code scanner. It told me I had a PO303, which was #3 misfire. I replaced that one with a new COP and my problem went away. I would check and clear codes for about a week. #3 was the only consistent one. I did get #7 once or twice, but I think that #3 being as bad as it was was giving false readings on #7 as I haven't had any issues since. There are $100 scanners that should be able to tell you what's wrong. Look for one that can read the CAN buss.
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Tuned
Joined: Dec 2007
Posts: 338
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From: Hooterville, WI
Wasn't it 05 that Ford went to OBDII?? I had no problems getting a code in my 01.
Tuned
Joined: Dec 2007
Posts: 338
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From: Hooterville, WI
That I don't doubt, it was very obvious that one was bad.
Elder User
Joined: Sep 2007
Posts: 803
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From: S CAL
All car manufacturers were mandated by the federal govenment to have
OBD II on their vechicles by 1996. Ford then came out later on their trucks with can bus also. That is why a OBD II scan code reader will not work on ford trucks with out the can bus capability also.
Fleet Mechanic
Joined: Aug 2005
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From: NJ
I own the above mentioned quick probe, it does work o.k. if you can it to misfire standing still and for a decent amount of time. Anyone with a scanner that can do a power balance test will be able to detect the misfire right away. I do many of these a week, as long as I can get it miss on a road test just a little I can pinpoint the cylinder in seconds.
Tuned
Joined: Dec 2007
Posts: 338
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From: Hooterville, WI
Except those over GVW of 8K. They will have all the outward appearance of OBDII but only have the programming of OBDI.