COP Burning...HELP!!! - Ford Mustang Forum
 
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post #1 of 12 (permalink) Old 07-30-2011 Thread Starter
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COP Burning...HELP!!!

2001 Saleen 4.6L Supercharger - this car sat for 2 years, I bought it and so far changes the fuel pump, put in new plugs, but other wise the car runs very well. After I changed the pugs (shortly) it started to have a misfire in of all places cylinder#2 ( under the throttle body) I though since was so hard to get the plug in that maybe I cracked it, new plug, ran good for about 25 mile then misfire again. Moved the COP to another cylinder, and that seem to be the problem. New COP car ran fine for about 15 miles and started to smell a burning smell. Pop the hood, damn things ON FIRE. Limped it home, burnt the COP and the pig tail.
Ohm'd wires out the seem to be the same as the other wires going to the other COP's. Check to see if there was a short with a continouity test, no short. Turned the key to the on position, the wires are getting 12v just like all the others going to the COP's. I thought maybe it has to do with when the car is driving, maybe there is a short intermittently so I traced the wires pack back the best I could and found only 1 spot that there could be a problem, taped it up real good and until I can get another COP and pigtail next week I won't know. ANY OTHER IDEAS FOR ME TO CHECK???? HELP I'M DIEING HERE!!!

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post #2 of 12 (permalink) Old 07-30-2011
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Need to understand how the tests were done. The COP are on a ground start circuit. Many ppl do not understand what that means and how it affects the test procedure.

A ground start device always has +12 volts when the key is on. The circuit is completed by grounding the return wire. So if a COP has excessive dwell, usually there are two causes.

There is a ground fault in the return wire.
The PCM coil driver is grounded internally (Bad coil driver).

The only true way to rule out a bad return wire is to remove the COP electrical connector AND the PCM connector. Measure the resistance of the return wire.

Also measure the resistance to ground. This should be "open" with both ends disconnected.

COP Cylinder #2 is PK/WH to PCM pin#104.

Got to be honest here. When a car has been setting for two years and then has a problem like this, I'm thinking water damage or rodent damage. Perform a through visual inspection of the wiring harness. If you find spots in the wire, don't just tape over the entire harness. You have got to look at the individual wires.

If the Ohm meter is showing a ground fault, one method to find the fault is to leave the meter attached and being wiggling the wiring harness. Look for the resistance value to change.

Do not drive the car until the problem is fixed. I remember helping someone that ignored the advice. The motor caught fire and destoryed most of the top end wiring in the entire engine bay.

Good luck.


2003 GT Convertible (sold & missed)
2000 GT coupe (Craigslist project. Fixed. Now my DD). Windsor to Romeo swap.
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post #3 of 12 (permalink) Old 07-31-2011 Thread Starter
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COP Burning

with the pigtail disconnected and wires stripped back it ohms out just like all the other 7 cylinders. When the key is on, I have 12v like is supposed to. There is no short when the car is in the garage. The last time I did this after installing the new pigtail and COP the car ran fine in the garage and threw no codes, its when I take the car out is when the COP burns up. So I did follow back the wiring harnass and found the only spot (visually) that I could see be a problem and inspected each wire the best I could being where it is situated to look for a bare wire. Found the two wires that were actually the closest to the bottom of the bundle and still covered by black tape and that corigatted black plastic to be a little worn, but not bare, and the colors do not match the 12v wire to that COP.
I guess the next step is your suggestion and measure the resistance between the wire.
With the wire connected to the PCM I get 152 ohms on that wire, exactly the same on all the other Cylinders, but I will remove the pin and check there next.
I can't express enough how much I appreciate you taking time and experience and helping out!!!

Thanks again
Russ
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post #4 of 12 (permalink) Old 07-31-2011
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are you sure you put sparkplug in right?


you say car sat 2yrs than you brought it?...

so your saying the car was owned by someone else and you got it with problems and have started throwing parts at it to try and fix and now on last test the coil caught fire, so now you dont know wtf to do...


is this a true saleen or molested gt
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post #5 of 12 (permalink) Old 07-31-2011
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Did you check the #7 spark plug? If the spark plug gap has closed, this could also cause the symptom.

I'm get the impression that some more information may help cement your understanding of the root problem.

It's a mostly useless test to measure the resistance between the two COP electrical connectors. Why? Because there's too many other devices in the circuit. Further, the coil drivers are active components being measured in a "dead" state.

Makes far more sense to measure resistance from the open COP return line to ground. This would look for a fault in the return line and the PCM coil driver.

Get yourself a set of "noid" style test lights. Most autoparts stores will rent them. Place the tester across the COP. The light would flash with each activation pulse. I suspect there will be a huge difference in the length of the flash (duration or dwell) for cylinder #2.

As a reminder when taking Ohm measurements, the circuit needs to be non powered. Any stray voltage will confuse the meter.

It doesn't surprise me that it works fine in the garage. It does take time for the heat to build up inside the COP. Also under driving conditions, the COP is being hit faster.

2003 GT Convertible (sold & missed)
2000 GT coupe (Craigslist project. Fixed. Now my DD). Windsor to Romeo swap.
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post #6 of 12 (permalink) Old 07-31-2011
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[quote=wmburns;2671634]Did you check the #7 spark plug? If the spark plug gap has closed, this could also cause the symptom.


did you mean #2 cyl?

just following along...
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post #7 of 12 (permalink) Old 07-31-2011
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I wish this site would give more than 30 minutes to edit posts.

More edit time, less perm typos

2003 GT Convertible (sold & missed)
2000 GT coupe (Craigslist project. Fixed. Now my DD). Windsor to Romeo swap.
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post #8 of 12 (permalink) Old 08-03-2011 Thread Starter
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Quote:
Originally Posted by wmburns View Post
Need to understand how the tests were done. The COP are on a ground start circuit. Many ppl do not understand what that means and how it affects the test procedure.

A ground start device always has +12 volts when the key is on. The circuit is completed by grounding the return wire. So if a COP has excessive dwell, usually there are two causes.

There is a ground fault in the return wire.
The PCM coil driver is grounded internally (Bad coil driver).

The only true way to rule out a bad return wire is to remove the COP electrical connector AND the PCM connector. Measure the resistance of the return wire.

Also measure the resistance to ground. This should be "open" with both ends disconnected.

COP Cylinder #2 is PK/WH to PCM pin#104.

Got to be honest here. When a car has been setting for two years and then has a problem like this, I'm thinking water damage or rodent damage. Perform a through visual inspection of the wiring harness. If you find spots in the wire, don't just tape over the entire harness. You have got to look at the individual wires.

If the Ohm meter is showing a ground fault, one method to find the fault is to leave the meter attached and being wiggling the wiring harness. Look for the resistance value to change.

Do not drive the car until the problem is fixed. I remember helping someone that ignored the advice. The motor caught fire and destoryed most of the top end wiring in the entire engine bay.

Good luck.
I pulled the the connector off the PCM, and just assumed that I could find pin 104 by counting the pins, but that must be wrong since there is only 102 pins, can you point me into the direction of a schamtic?
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post #9 of 12 (permalink) Old 08-03-2011
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Quote:
Originally Posted by rjtantillo View Post
I pulled the the connector off the PCM, and just assumed that I could find pin 104 by counting the pins, but that must be wrong since there is only 102 pins, can you point me into the direction of a schamtic?

from this site...chiltons
Gale Cengage Product Failure

wire diagrams on left at bottom of menu..click + signs...look for connectors...

if you use the search function at top of menu you must click on search for it to work..using enter on key board it will not work
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1999-2004 PCM connector C294

Connector C294. Remember to measure the resistance of the wire itself. Should be low.

Check for a ground fault. Measure between the wire and a known good ground. Should be high.

Good luck. If these tests are good, next step is for focus on the PCM itself.

hotcobra03, Are you the same ID on Stangnet?

2003 GT Convertible (sold & missed)
2000 GT coupe (Craigslist project. Fixed. Now my DD). Windsor to Romeo swap.

Last edited by wmburns; 01-01-2015 at 01:56 PM.
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post #11 of 12 (permalink) Old 08-04-2011 Thread Starter
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Quote:
Originally Posted by hotcobra03 View Post
from this site...chiltons
Gale Cengage Product Failure

wire diagrams on left at bottom of menu..click + signs...look for connectors...

if you use the search function at top of menu you must click on search for it to work..using enter on key board it will not work
This also came in handy....Thank You all again for your help!!!

http://fordfuelinjection.com/index.php?p=88+
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Quote:
Originally Posted by rjtantillo View Post
This also came in handy....Thank You all again for your help!!!

Ford Fuel Injection 4.6L harness

this link is good but it doesnt give the referance values of the pins..

referance value is what your to be reading with a tester...

and wmburns...thats a yes...im am on a couple of sites and use the same screen name on all
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