Cracked Ignition Coil

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.

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

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.

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

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.

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.

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

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.

That's worth a try.

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

http://i420.photobucket.com/albums/pp290/jabrunn/crackedignitioncoil.jpg

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

http://i420.photobucket.com/albums/pp290/jabrunn/crackedignitioncoil.jpg

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.

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

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.

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.:headshake

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.

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

-Rod

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

-Rod

Don't know yet. Check engine light isn't on and I haven't dropped by Autozone to get them to check for any pending codes.

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.

With a bad valve and warped head, was your problem all the time or intermittent? Mine is intermittent, and as a matter of fact, the engine runs well the majority of the time. That's why this is so puzzling. I know there is a TSB listed for the 2002 Taurus with the Vulcan engine for P0300, P030X and P0316 codes at Alldata.com. I've seen lots of posters on here and another automotive forum with the same problem. I did have a pending P0303 at one time and that one seems to be the most common one on both forums.

I did run across a friend's Contour with the 2.5L Duratech V6 that had a random misfire, but no misfire codes. Her car was pre-OBD2 so it didn't have quite as nice of diagnostics. What I ended up finding by accident on that one was a broken wire for the fuel injectors. After unsuccessfully searching for the misfire a few times, the car left her stranded at work one day, cranked but wouldn't start, had spark and fuel. I backprobed the fuel injection wiring with an oscilloscope to scope the injector signal, had her crank the engine and the car started. I found that if I wiggled that connection, I could get the car to stall or restart. The connection for the injector main feed was intermittant in the harness. I fixed the connection and the no-start and misfire never returned. For what it's worth, her boyfriend had previously tried a new coil to no avail.

-Rod

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

-Rod

Not sure. Auto Zone was closed when I got off work so I'll have to get the pending codes (if any) checked tomorrow. I know I still have a miss so something should be pending but who knows.

I did run across a friend's Contour with the 2.5L Duratech V6 that had a random misfire, but no misfire codes. Her car was pre-OBD2 so it didn't have quite as nice of diagnostics. What I ended up finding by accident on that one was a broken wire for the fuel injectors. After unsuccessfully searching for the misfire a few times, the car left her stranded at work one day, cranked but wouldn't start, had spark and fuel. I backprobed the fuel injection wiring with an oscilloscope to scope the injector signal, had her crank the engine and the car started. I found that if I wiggled that connection, I could get the car to stall or restart. The connection for the injector main feed was intermittant in the harness. I fixed the connection and the no-start and misfire never returned. For what it's worth, her boyfriend had previously tried a new coil to no avail.

-Rod

I hope mine isn't a wiring problem. I don't have access to an oscilloscope (without paying for it) and don't want to have to trace a short in the wiring. If that is what it is though, then so be it. At least from what I've heard using my stethescope, the injector on cylinder 3 is working. Hopefully I'll know more tomorrow after I get any pending codes read. I really need to purchase a good scanner.

I hope mine isn't a wiring problem. I don't have access to an oscilloscope (without paying for it) and don't want to have to trace a short in the wiring. If that is what it is though, then so be it. At least from what I've heard using my stethescope, the injector on cylinder 3 is working. Hopefully I'll know more tomorrow after I get any pending codes read. I really need to purchase a good scanner.

There are no pending codes on my PCM. The other day, with the tank only 1/4 full, I dumped injector cleaner and fuel system cleaner in. The car has run much better since. I purchased a new fuel filter and am waiting for my Ford fuel line adapter to arrive for my fuel pressure gauge so I can check all of that and replace the filter. I am leaning toward a fuel delivery problem (filter, pressure regulator or pump) or possibly something in the EGR system.

Please keep us informed with what you find.

Be sure not to over tighten the new Ford fuel line adapter. That seems to easily tear up the gaskets in the adapter and cause them to leak.

-Rod

Please keep us informed with what you find.

Be sure not to over tighten the new Ford fuel line adapter. That seems to easily tear up the gaskets in the adapter and cause them to leak.

-Rod

Thanks for the advice.