Epic ignition coil failure

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Feb 6, 2021
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So today at around 4:30pm, I was going to get mad kombucha from the grocery store.

The beginning of the trip nothing was wrong, but about 1/4th the way to the store, the abruptly jerked. I was thinking I had hit something, so I was like oh well.

Half way towards the trip, the jetta started jerking like crazy on and off, I thought I was at a rock concert or something. Flashing CEL comes on, oh great what could this be?

I pull into the parking lot and next thing you know the engine sounds like it has a dead cylinder or two.

I turned the car off, on ignition, and put my cheap creader scanner in.

Misfires on cylinder 2 and 3.

Towed the car home, and found the ignition coil to be at fault. Ordered a new ignition coil and 4 bosch spark plugs from ecs tuning.
 
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Coils are a common failure - nothing out of the ordinary. What made this situation epic? I was expecting to read that the coil exploded or something.
 

Astro14

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I understand the word “Epic” differently. If the car continued to run, the failure of this one component could have been much worse. I have had coil failures that resulting in the car not running. One of the advantages of the coil on plug architecture is that a single coil failure enables the car to continue running. Not well. But running.
 
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I replaced the coil on my 1991 F-150 right before we moved here. I had changed out the plugs, wires, rotor and cap. So I figured why not change out the coil? It was the original, and has been broiling under the hood since I drove it home from the dealer. Besides, it was easy to get at, and the wire set came with a new coil wire.

I bought a new Accel High Performance Coil for just $58.00. So rather than wait for it to fail, I just swapped it out with everything else. Now everything for the ignition is new, from the distributor post to the threads in the cylinder heads. For a little over $50 bucks the peace of mind is well worth it.
 
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So today at around 4:30pm, I was going to get mad kombucha from the grocery store.

The beginning of the trip nothing was wrong, but about 1/4th the way to the store, the abruptly jerked. I was thinking I had hit something, so I was like oh well.

Half way towards the trip, the jetta started jerking like crazy on and off, I thought I was at a rock concert or something. Flashing CEL comes on, oh great what could this be?

I pull into the parking lot and next thing you know the engine sounds like it has a dead cylinder or two.

I turned the car off, on ignition, and put my cheap creader scanner in.

Misfires on cylinder 2 and 3.

Towed the car home, and found the ignition coil to be at fault. Ordered a new ignition coil and 4 bosch spark plugs from ecs tuning.
I dont know the year but some MK IV had issues with cracks in the coil, many of these cars had their under engine splash shields tossed away at some point. The expensive fan controller had failures also due to the side shields missing.
 
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I dont know the year but some MK IV had issues with cracks in the coil, many of these cars had their under engine splash shields tossed away at some point. The expensive fan controller had failures also due to the side shields missing.
There was also the TSB for an additional ground for the coil
 

Astro14

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And if you drive it like that long enough, soon you'll either be buying or punching out a catalytic converter.
No.

Because when the ECU (at least, on six of my cars) detects the misfire, it no longer pulses the injector for that cylinder.

The car will run poorly, but it won’t damage the cat, or engine, because there will not be any unburned fuel to wash down the cylinder walls or load up the cat.
 
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No.

Because when the ECU (at least, on six of my cars) detects the misfire, it no longer pulses the injector for that cylinder.

The car will run poorly, but it won’t damage the cat, or engine, because there will not be any unburned fuel to wash down the cylinder walls or load up the cat.
Isn't that the same basic technology MDS uses? Or do they also dump the compression by allowing a valve to remain open?
 

Astro14

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Isn't that the same basic technology MDS uses? Or do they also dump the compression by allowing a valve to remain open?
I don’t own an MDS a car, but I had thought the valves stay closed, so that the cylinder is sealed to minimize pumping losses. More of a spring (compression and extension) than a pump moving air through.
 
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I don’t own an MDS a car, but I had thought the valves stay closed, so that the cylinder is sealed to minimize pumping losses. More of a spring (compression and extension) than a pump moving air through.
That could very well be true. I have a 5.7 HEMI with MDS, but I have no idea how it works. As much as I have tried, I can't feel it cutting in or out. I couldn't even tell you if it's working or not, because there is absolutely no jerking or anything to give a sense of it operating. The 5.7 HEMI also has VVT, (Variable Valve Timing).
 
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