The bearings in the original distributor started going, so we installed a new distributor. The ICM failed with less than 500 miles. Yesterday I put on a new module and coil. I started driving this morning and tach started jumping around. I know it needs a new tach filter, which I ordered this morning ironically. This afternoon I went to start the car and again no spark. Now I have lots of questions, but I' thought of starting with has anyone anyone experienced this? I don't think there is a short because the old distributor worked great, beyond the bearings. I bought another new distributor and plan to replace it out tomorrow. The car is at my work's car park.

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Olliesdad

yes, a lot of us have had trouble with the ICM. Your distributor is probably fine.

ICM issues:

1. They are not built as well as they used to be: many are bad before you buy them, or go bad after a brief time.
2. They can be ruined by other bad parts in the system, including spark plug wires, connectors, and ignition coil.
3. They are often sold with the wrong kind of heat sink paste....clear instead of white.
4. Delco ICMs tend to be more reliable than 'house brand' ICMs, but not by much.

[This message has been edited by Gall757 (edited 08-16-2017).]

Poor grounds, bad ignition coil, bad plugs or wires can put stress on an ignition module. Those can be a cause of failure. If you used the clear grease that came with the module, that could be a contributing factor. Grab a tube of white or silver heat sink paste from your local computer store or Radio Shack. It has better insulating qualities.

First, thank you so much for taking your personal time to help me!

I used the white gease that it came with. I tried to buy some extra yesterday, but Autozone was sold out. It's honestly my luck! This morning I went to get the car washed and just as I pulled up the car wash just stopped and wouldn't turn back on! Then the Fiero not starting was just icing on my bad day!

I had read that a bad tach filter could also kill the ICM, so I thought maybe that was it too. These things are not cheap, Autozone charged me $50 for that new ICM.

Thanks again for all of your help!

For a better deal on an ICM, visit Ebay.

http://www.ebay.com/itm/Ign...AOSwEzxYQaJf&vxp=mtr

[This message has been edited by Gall757 (edited 08-16-2017).]

That's less than half what amazon is charging! THANK YOU SO MUCH! I'm going to order one right now.

Jump to 4:20 in this video - https://www.youtube.com/watch?v=S8Z4iv7-Ke8

When you have high resistance in the secondary, or you have worn out plugs with too large of a gap, or you pull off spark plug wires when running, the voltage in the ignition coil can build to the point that the spark jumps from the secondary to the primary inside the coil. When this happens the ICM usually gets shocked. An indication that this is happening is a jumping tach and multiple ICM failures. Replacing just the ICM does not fix the root cause.

Have you replaced ALL your spark plugs including the three hard ones to reach? Then check the resistance of the spark plug wires. They should be less than 20K ohms per foot. If old you should just plan on replacing them. Then once you have replaced or checked the plugs and wires, you should replace the coil. The coil will have been damaged and the jumping spark blasts a hole in the insulation. That hole will allow the spark to jump to the primary at a much lower voltage.

If you are shocking your ICM, expect it to fail. It should last a long long time in a properly working ignition system.

Thank you again to everyone for their help. @Phonedawgz, thank you for the video because I never knew what the ICM actually did. It turned out to be a faulty ICM, but I went cheap on the distributor before so this time I bought a better one and timed it. It's been running great all day. I unplugged the tach filter until the new one from Rodney comes in. I am very thankful for Rodney too! I don't think it's the spark plugs or wires because they were replaced in the last 5k miles. And yes, the back ones were changed. I ordered the rubber strip from The Fiero Factory to keep them from rusting up again, I would rather watch for the leaves on a car that gets put up for the winter in Sept than go through getting rusted plugs out again. If something happens, I will post an update but I hope this thread might help another Fiero owner someday. Cheers! Tom