c.o.p caught on fire

What?!?

Never heard of anything like that happening. I can understand the origional COP possibly shorting out due to deterioration and old age, but thats crazy the brand new one did the same thing.

Did you replace the ENTIRE coil itself, or just the boot/wire?

Maybe you have a short in your wire harness, or for some reason that part of the engine is producing extreme heat.

bad voltage will cause caps and transformers to fry (in ac voltage). One thing to do would be check the voltage or amps at the plug for the coil. I have no idea what the specs for this would be. Since you only bought the coil today Im sure you can return it. If it was my car and it happend again or you find the signal to be out of range it might be time for the stealership to look at it. Good luck!

..wonder if the module is allowing the coil to turn off.
maybe the coil is constantly firing...or your melting it with Amps, this may sound crazy but go ahead and check for an amp leak at the alternator.

maybe compare the voltage to a couple of other coils? see if the bad one is acting different...

I think jbauer is close.

Each COP has 2 wires. One is red. The other depends on the cylinder, but is always 2-color (solid with a stripe), and never red. The red wire will be at battery voltage whenever the ignition is turned on. The striped wire is pulsed by the Powertrain Control Module (PCM), turned on just long enough for the current to ramp to a preset value (usually in the 4-6 amp range), then immediately turned off to generate the spark. High coil current (which equates to heat) should occur for only a small percentage of the time. If a COP is energized all of the time, it will overheat.

I can think of 3 conditions whereby the a coil would have excessive power dissipation.
(1) The peak current is not attaining the preset threshold (which is checked by the PCM at every spark), so the PCM is holding the coil (COP) on too long. This could be the result of a bad connection or corroded wire to that COP that limits the current.
(2) The PCM has failed and is energizing that COP 100% of the time.
(3) The wire between COP and PCM is shorted to chassis, which will also keep the COP energized 100% of the time.

In the case of (1), the engine may seem to run normally. One cylinder may have a weak spark, and the MIL ("service engine soon" light) should eventually turn on.
In the cases of (2) and (3), there will be no spark generated and you should feel a miss, particularly under load.

With the ignition on, but engine not running, both COP wires should read battery voltage, and all COPs should be no warmer than the metal they are bolted to.

With the engine at idle, the red wire should still be at battery voltage, but the striped wire should be lower in voltage (but nowhere near zero). As RPM increases the voltage at the striped wire will go down. Comparison to a known good COP is a good idea.

Be careful when making measurements with the engine running. Voltage spikes on the striped wires can reach 400V. A shock could cause an involuntary reflex that places a body part in peril. Some precautions include standing on a piece of wood, keeping one hand in your pocket, and placing an insulating blanket between your leg and the fender.

I recommend having the PCM tested before installing any more new COPs (unless you don't mind sacrificing them to science).

You obviously know how to use a voltmeter, which should help a lot.
Did you make the measurements by first removing a connector and probing into the pins, or were you able to make measurements with the COP still connected (this sometimes involves piercing the wire)?

Sorry about the wire colors. I have a 2001 wiring diagram and thought they would be the same for 2000.

Let's assume for now the measurements are with the COPs still connected. The "10V and pulsing" seems normal to me. At idle (~600RPM), each coil is pulsed one for every 2 engine revolutions, or approximately 5 times per second.

Does the other COP wire read battery voltage (~14 - 16V if the engine is running; ~12-13V ignition on but not running)?

Do you have the negative probe at chassis ground, or are you measuring between the 2 COP wires? If the latter, then >12V means either a driver that is always on, or a short somewhere between the driver and COP.

COP drivers have a very low failure rate in normal use . . . less than 10 per million, but it does happen. Unfortunately, the individual driver devices are usually not separately replaceable; they just replace the entire PCM.

Was any work done under the hood or in the vicinity of the PCM just before the first COP melted?

OK, i'm gonna tell you what it can be..to my knowledge, and i strongly believe you'll find your answer in one of these. this is ALL that it can be..if you think i know what i'm talking about use this as a guidline.

*You are suppose to have a constant 12V to that wire you tested..so you are good in that department.

* Voltage well not cause your C.O.P to catch fire, AMPerage CAN and WILL.

*The first thing is the coil.. typical coil has about 0.5 Ohms of resistance..any less then that you start running into trouble..in some weird way, it could be possible your old coil failed, AND that the new one was also defective in the same manner.. If this is the case, you need to Sue the living CRAP out of Ford or whoever in mexico manufactures those coils.

*Secondly, This is the TEST YOU MUST DO.. you MUST check for amperage.
You need to put your meter in series with that cylinder. (Make sure you have the exact Appropriate fuse in your meter for the amp scale, or you'll be out how ever much you paid for that meter)

I'll tell you right now, if that fuse blows you found your problem.. IIRC most meter fuses are like what, 10 amps? anything close to 10 amps, you found your problem.

*Thirdly, if you find excessive amperage (i'm willing to bet you will..for your sake) you are shorting out somewhere. Something, some where is shorting.. what your going to do is bust out the wiring diagram, and your going to trace the 2 wires from the harness that goes to the coil.. your going to cut all the electrical tape, etc. etc. and trace those two POS wires every which way they decide to frikin go.. and find out where they are shorting and look for any opens or something.

* 4th...this is my second car, I haven't been around a LOT of Fords, although they are my preference..my parents drive imports and stuff. But, to my knowledge, there is no module for Fords COP design.. if their were, the only place i imagine it could of been was on top of the coils themselves, sitting there waiting for a signal from the ECM..
To my knowledge, the trigger module for the coil is integral with the on board computer.. if it's malfunctioning then yes, it CAN do what you say, and yes, it CAN be limited to only one cylinder...in which case, if you haven't ever played around with a tuner and stuff.. i'd still sue the living crap out of Ford..because this is america and we can

The PCM fires the COP by grounding the COP as you guys have discussed.

You can tell if the issue lies with the PCM or the wiring by unplugging the connector to the PCM and checking if the ground wire connected to #4 coil is still shorted to ground.

Put your multimeter to test continuity and one lead on the #4 COP ground wire and another lead on a good chassis ground. If there is continuity with the PCM unplugged then your problem is with the wiring. Move the wiring around and check if the line shorts. If there is no short then the problem is with the PCM always grounding out that line and you will need a new PCM..

Riley

Not sure which one is the hot wire.

Check one of the COPs that has the single "red" wire (that will be the +12v wire) and note if it's on the right or left side of the connector. It will be the same on the #4 COP.

Riley

well, regardless if you find continuity your going to end up having to trace those wires Lol, theres no way around it..unless your hoping for a fried PCM hehe

Good luck bud, i really hope you find it

Jbauer said:

well, regardless if you find continuity your going to end up having to trace those wires Lol, theres no way around it..unless your hoping for a fried PCM hehe

Good luck bud, i really hope you find it

Click to expand...

If he gets continuity with the PCM unplugged then yes, he will need to trace wires since the wire is grounded without the PCM grounding it..

Now, if he doesn't get continuity then the wires are most likely fine and he can look towards the PCM.

Riley

Skud said:

If he gets continuity with the PCM unplugged then yes, he will need to trace wires since the wire is grounded without the PCM grounding it..

Now, if he doesn't get continuity then the wires are most likely fine and he can look towards the PCM.

Riley

Click to expand...

Thats what i said.. Damn, commas PWN me

I got lucky and found a 2000 GT powertrain control wiring diagram.
The( White - blue stripe) wire is common to all 8 coils and is at battery voltage whenever the ignition is On.
The (Green - violet stripe) wire goes to an IGBT driver transistor in the PCM. This driver turns on to provide a path to Ground to charge the coil, then turns off to transfer the stored energy to the spark plug.

I agree with Skud; the only wat to be absolutely sure you do not have an external short from the Green-violet wire to chassis is to disconnect the PCM, and then measure between the COP connector pin and Ground with an ohmmeter. An open circuit means no wiring short, and therefore the problem is within the PCM. Touch the meter probes together first so be sure it recognizes a short OK.

I recommend disconnecting battery negative terminal cable before pulling the PCM connector, so as not to accidently create any new problems. The PCM may have multiple connectors (the wiring diagram is not clear on this). At least one of them has 104 pins. So you mighty have to remove them all.

I don't know where your PCM is located. On my '03, it is behind the trim panel just to the right of a front-seat passenger's right ankle. There are other connectors blocking access that have to revoved first (digital pictures come in handy when it is time to reassemble).

When you reconnect the PCM, the car may feel different for a few driving cycles, since the dynamic memory will have been erased.

If you are willing to settle for 80% confidence, would prefer not to disconnect the PCM, and have a good ohm meter that can read less than 1 ohm, you can try this:

-1- Disconnect the battery negative cable.
-2- Measure the resistance between the (white-blue) wire connector pins on two different COPs, one on each side of the engine. This will give you some idea of the resistance of the wiring harness. The reading should be less than 1 ohm.
-3- Now, measure the resistance between the COP #4 green-violet wire and the negative battery cable (not the battery terminal). Reverse the probes and read again.

If both readings in step -3- are identical and similar to step -1-, there is a good chance a wiring short exists (remember, this method does not provide 100% certainty).

If the readings in step 3 change when the probes are reversed (one might even be an open circuit), you most likely have a problem within the PCM. Semiconductor devices often fail with a polarity-dependent resistance. In this case, the confidence factor is closed to 95% you have a defective PCM.

I could get you the IGBT driver transistor free (the company I work for makes them), but I don't think the Visteon PCMs are user-serviceable. They usually fill them with a gel-like silicone material for better resistance to heat, humidity, and shock.