Cracked Ignition Coil

[brunnj]

I have a 2002 Ford Taurus with the 3.0L OHV Vulcan engine. I have been experiencing a miss on and off since owning the vehicle. I have replaced the wires and plugs and it still misses. I have loaded the system down with fuel injector cleaners and it still misses. Today I pulled the ignition coil and found a crack along the side of the 3-4 coil pack. I have also had a pending code showing a misfire on cylinder 3 at one time. I suspect this is my problem. Am I correct in assuming this? I wanted to include a picture clearly showing the crack but I could not get that feature to work.

[shorod]

Sounds like a reasonable conclusion that he cracked coil pack is the issue. In a dark area with the hood open and the car running, can you see sparks from the viscinity of the crack?

-Rod

[brunnj]

Originally Posted by shorod

Sounds like a reasonable conclusion that he cracked coil pack is the issue. In a dark area with the hood open and the car running, can you see sparks from the viscinity of the crack?

-Rod

I ran the engine for a little bit and watched the coil and saw no sparks. The engine was most of the way to operating temp. The miss is intermittent and occurs when the engine is thoroughly warm, with low rpms and slight load on the engine. It would be nice if I could mount a camera under my hood to record the coil as I drive.

[shorod]

You could pick up an inline spark test (they're around $3 from Harbor Freight) and see if you can see the misfire in the spark tester when the car is idling. Install the tester between the coil and plug wire. If the light drops out (indicating no spark) and with the apparent crack in the coil housing, that's probably a good indication that you have a bad coil. If you really wanted to be sure, you could find a portable 2-channel oscilloscope, watch the coil primary on one channel and use a high-voltage probe to watch the secondary of the same coil to make sure you have primary trigger even when you don't have secondary spark. That would pretty much guarantee proper diagnosis as long as you have good plug wires, good plugs, and good connections.

-Rod

[brunnj]

Originally Posted by shorod

You could pick up an inline spark test (they're around $3 from Harbor Freight) and see if you can see the misfire in the spark tester when the car is idling. Install the tester between the coil and plug wire. If the light drops out (indicating no spark) and with the apparent crack in the coil housing, that's probably a good indication that you have a bad coil. If you really wanted to be sure, you could find a portable 2-channel oscilloscope, watch the coil primary on one channel and use a high-voltage probe to watch the secondary of the same coil to make sure you have primary trigger even when you don't have secondary spark. That would pretty much guarantee proper diagnosis as long as you have good plug wires, good plugs, and good connections.

-Rod

The problem is the engine doesn't misfire at idle, at least I haven't noticed it. It only happens while I'm driving, usually at a steady speed with the engine under a slight load (going up a hill).

I purchased a new set of Borg Warner plug wires and Motorcraft plugs to go in the vehicle. The connections seemed very good and secure. The car starts up easilly and idles very well. The problem only begins to occur once I have driven for a bit and warmed the engine up completely, and then it only does it intermittently.

[brunnj]

Originally Posted by brunnj

The problem is the engine doesn't misfire at idle, at least I haven't noticed it. It only happens while I'm driving, usually at a steady speed with the engine under a slight load (going up a hill).

I purchased a new set of Borg Warner plug wires and Motorcraft plugs to go in the vehicle. The connections seemed very good and secure. The car starts up easilly and idles very well. The problem only begins to occur once I have driven for a bit and warmed the engine up completely, and then it only does it intermittently.

BTW, how do I post a picture on this forum. I tried using the Insert Image button above but it did not work even though I pointed to the correct location on my hard drive.

[shorod]

You need to post the image to the Internet using an image sharing service such as Photobucket or similar.

If you power brake the car, with the wheels properly chocked of course, can you get the misfire to occur?

-Rod

[brunnj]

Originally Posted by shorod

You need to post the image to the Internet using an image sharing service such as Photobucket or similar.

If you power brake the car, with the wheels properly chocked of course, can you get the misfire to occur?

-Rod

That's worth a try.

[brunnj]

Originally Posted by brunnj

That's worth a try.

I created a photobucket account so I'll see if the photo will show up.

[brunnj]

Originally Posted by brunnj

I created a photobucket account so I'll see if the photo will show up.

After reexamining the coil, I have found multiple cracks. The one in the photo is the single largest crack. You can't tell from the photo, but it is actually splitting. I've put epoxy on all of the cracks to see if that will get me by until payday.

[shorod]

That does look a bit suspicious. Hopefully you didn't have any appreciable moisture in the coil when you epoxied it and that gets you by for a week or two. Just don't expect the epoxy to be a long term fix and let a replacement fall off your budget if it does get you by until payday. If the crack was the source of the misfire, there's likely more internal winding damage that is allowing the field to collapse through the crack.

-Rod

[brunnj]

Originally Posted by shorod

That does look a bit suspicious. Hopefully you didn't have any appreciable moisture in the coil when you epoxied it and that gets you by for a week or two. Just don't expect the epoxy to be a long term fix and let a replacement fall off your budget if it does get you by until payday. If the crack was the source of the misfire, there's likely more internal winding damage that is allowing the field to collapse through the crack.

-Rod

The epoxy didn't fix the problem. It's actually a bit worse. I'll be replacing this coil on thursday.
Thanks for your feedback.

[brunnj]

Originally Posted by brunnj

The epoxy didn't fix the problem. It's actually a bit worse. I'll be replacing this coil on thursday.
Thanks for your feedback.

Ok, here's what I've done to no avail.
I purchased a Borg Warner coil and installed it. I also replaced the elbow on the PCV valve hose and the PCV Valve as the elbow was cracked and brittle. I have new Borg Warner plug wires and new Motorcraft platinum plugs. I am still experiencing a bad miss. It often feels like the engine while driving will just lose power (without shuddering) and then it will often miss (with a hard shudder) while the engine is at cruising speed and under slight load. I am waiting on a replacement Ford fuel line adapter for my fuel pressure gauge so I can check that. I have listened to my injectors operate with my stethescope and I can hear them all clicking at idle even while revving the engine. I have loaded the system down with fuel injector cleaners as well.

I haven't done a thorough check for vacuum leaks or checked compression. Anyone else have any suggestions that I might try or maybe you have experienced before. Thanks.

[RoB51988]

If you havent messed with the hoses I dont see why any of them would be leaking. The only time I ever had a misfire with lack of power while driving is when I had had bad valve and warped head. Do a compression test and see what it comes up with.

[shorod]

Do you still get a misfire code for cylinder #3?

-Rod