2000 Bonneville w/125,000 miles. 6 weeks ago, my MAS had to be replace, and while I had the car in for repair(Dodge dealership), I went ahead and had them replace plugs/wires since this had never been done. Car ran fine until last week my check engine light came on, flashing, car running extremely rough. Luckily I was only a mile from home, so I was able to drive it back. I have a Ford mechanic friend with a scan tool that showed only code P0300. He then pulled each wire from it'* coil checking for spark, and the 1-4 coil wasnt showing any spark. I replace the coil but no change. He suspected the ICM, so I replaced that but no change. I guess it could be that both wires and/or plugs went bad, but I find that hard to believe both would go bad like that. Any ideas what else could cause this scenario?

Thanks
Bob

You say he checked for spark at the coil right?

That'* a pretty odd problem, the items that drive the coil to fire are the ICM, and crank sensor. I don't recall if the PCM has anything to do with the actual control of the spark other than timing.

Check the terminals on the ICM for any corrosion.

BillBoost37....Yes he checked for spark by removing the plug wire from the 1-4 Coil and no spark was visible from either 1 or 4 terminal....he did the same test on the 2-5, & 3-6 coil and good spark was there.

I'm no mechanic, but doesnt the crank sensor signal go to the ECM, and the ECM is what tells the ICM which Coil to fire?

Ok, it'* not the plugs or wires then. It'* like you are thinking....

I haven't had an issue like this, therefore I am not familiar with the whole path of A to B and then C on how we fire certain cylinders. Makes sense though because we case or crank variation learn the PCM. Which would mean the PCM needs to know TDC for correct firing.