Engine misses / low power - Ignition Module & test?



My 1999 Saturn SL1 was running well. One evening, I started it up to go home, and it wasn’t running well, and barely had power to make it the half mile home. It still starts up, but seems to miss in park and in gear.

We tried spark plugs, wires, coils, catalytic converter, cylinder pressure, crankshaft position sensor, and fuel filter with no change in engine behavior. I think the EGR valve was looked at and passed. I hope it is not the fuel injectors as I put a cleaner in the fuel every so often. Could it be the Ignition Control Module, and is there a way to test the existing module? What else could it be, and how could I test it?


Ok Miles would be a good thing to say. Have you replaced the timing belt? Any engine codes? Seems like you have tossed a lot of parts at it. It could be injectors, poor fuel pressure, bad temp sensor, bad air pressure sensor. Does it run better warm? A bad icm should throw a code. Have you had the car scanned for stored codes. Many parts stores will do this for free. If you get some post them here.


Thank you for the interest. I think it has about 140K miles. I believe it has a timing chain and not a belt. Engine codes: P0340, P0341. Both codes relate to the camshaft sensor. This Saturn does not have a camshaft sensor. If I remember, the fuel pressure checked out fine, and the temp sensor looked to be visually fine, though it could be internally bad. I don’t think it runs better warm.
Is there a specific code for an Ignition Control Module? Is there a way to test an Ignition Control Module?


Don’t quote me on this but I’m pretty sure that many big box auto parts chains can test an ignition module. There is a good chance that it has an issue since it is actually the thing that sends to cam signal to the PCM. Here is a very good write up of how it works:


Thank you for the suggestion. I made a few calls and found an AutoZone in the area which is able to test the Ignition Control Module in their store. I will let you know how that goes.


I took the ICM to AutoZone. Their test said the ICM was okay. This was not the answer I was hoping for. A mechanic friend said their test may not be able to check all the functions of the ICM.
I then had the car towed to Hill Auto Electric, figuring they would be able to solve what seems to be an electrical problem. They found that there was no spark to the #2 & #3 cylinder, and traced the lack of spark to the coil. They also checked the two wires that send signals from the PCM to the ICM to tell the #1&4 cylinders to fire and the #2&3 cylinders to fire. The wires were sending the same voltage from the PCM to the ICM. This meant the problem was the ICM or the coils, and as I already checked the coils, it had to be the ICM.
I bought a new ICM, installed it, and the engine runs fine again. (Now I am on to a transmission leak problem.)


Thank you for the follow up. It is surprisingly rare. And thanks for the implicit heads up about the auto parts store ignition module testing. I’ve never had reason to do it but was always wondering…