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In the same thread @gw082008 suggests testing the icm directly with a rig off the car. I have created this rig, I would like someone (@gw082008?) to validate I have set it up properly. In do not get a spark in my rig. I have another ICM I will test with tonight.
Maybe I also have a bad coil in my rig, I also have a spare to swap in. Both coils pass the 3 resistance tests published elsewhere here.
I am most concerned that the rig is legit since I had to interpret what gw said and the FSM diagram too.
I do have to do the AC voltage pickup test on the distributor too.
This all came about when I was idling along at about 15 mph after 30 mi of driving and the engine shut with a no spark condition. Good fuel pressure and no other electrical problems I can see. My aged MSD 6AL is testing bad so I wonder if in failing it took out other stuff too.
The only thing I see is that the battery ground to the ICM mounting eyelet. It may not be a good enough ground. Mount the ICM on a aluminum plate, which is needed for heat sinking anyway, and ground that plate to the battery.
The schematics are how I bench test my ICM & coil circuits.
Hope this helps!
I have a spare distributor so it makes it a bit easier to test.
Rbob is correct so make sure you properly ground the ICM.
New Years day my Firebird also stalled and would not restart so I assumed my ICM had failed.
Turns out it was actually the coil - it ohmed within specs but would not fire a spark plug.
Good Luck!
Hey Rbob thanks for stopping by, always nice to hear from you. GW thanks for your input to.
I've never dug into the ignition in the many years I've owned the car, from the PO it had an MSD6A, blaster coil, and Cardone distributor. I did put new sp wires on at some point.
I would occasionally chase a no spark which mysteriously went away when I swapped in the backup ICM and swapped back the original.
That MSD6A and the blaster coil made a hellacious spark and noise when I hooked up the spark plug tester to the coil so there was no doubt it was good. This was all in the car.
Now with my permanent no spark I believe i have my rig all set up outside the car (sans the 6A which failed a spark test) per my diagram and GW instructions including using an old dist as the base. I have attached a pic of the rig.
What I note:
* I could not get a spark from my two ICM's or my two blaster coils.
* I got a new cheapo ICM and coil this morning to get a baseline going.
* I do get spark with my cheapos, but it is nowhere near what the MSD6A/blaster put out.
* The cheapo coil gets warm to the touch after about 20 taps of the test wire.
It seems at this point I have two bad ICM's, two bad coils, and a bad 6A.
Should I be able to hit the test wire as fast as I want and get a spark every time?
Also, this is a twin turbo car, and I am at about 12 lb of boost right now. I want to dial in more, what should I do for a permanent solution regarding the ignition? Another 6A?
FWIW if your ICM is a different brand than your coil then you can have issues of one messing with the other. I've had issues with Accel coils and parts store ICMs, MSD coil and parts store ICMs, a brief stint of MSD coil and MSD ICM, and finally the best result with no problems (knock on wood) has been just going back to an AC Delco Coil and an AC Delco ICM. As additional insurance I created a heat sink that mounts to the bottom of the distributor (I'm running a large cap HEI).
I recommend ditching the MSD 6AL and go back to stock.
Just so I understand what I should be getting from the rig, every time I put 12v on the ICM I should get a spark right? It seems like I don't always. I also get residual sparks after I apply the 12v.
Maybe I should just bite the bullet and get ACDelco ICM and coil and use that as my baseline. Right now it's a parts store mixed setup. So annoying can't even get it to act predictably.
Update - installed new OEM stock coil and new OEM ICM. Still no spark. Grrrr. Following the attached diagram to step 5. Question - step 5 references Figure 1, see where I drew in the 8v power supply, where do I connect the 8v ground to?
I did not find an answer to my question above, but on checking my whole setup once again I found
1. the test spark plug/alligator clip combo was missing the electrode - maybe I was getting spark but it would not spark through that thing.
2. inside the dist the connector from the pick up coil to the ICM maybe had a pin inside the connector pushed back preventing a connection.
She started. Whew.
Remember you can test for spark with the plug wires off the dist cap and the dist cap off. Just ground via spring clamp a spare spark plug against something metal under the hood and run the coil to it.
I was recommended to find an ICM ending 369 printed on it but my new OEM ICM had a different number printed on it. I was also recommended to get an OEM coil made in the states but my new one had Poland, Mexico and China on it.
05-31-2023, 09:28 AM
