Hello. New to the forum, thanks for any and all advice.

Got a 1994 G20 last year for a deal, was expecting problems but has run fine until recently. Started it up one morning when it suddenly died while idling. It would crank but not turn over. I changed the fuel filter last year so I'm assuming its probably not that. I crawled under the van, had a friend half turn the key and could hear the fuel pump engage. Changed the spark plugs, cables and ICM. After this it would turn over and run, but if I let it idle at a light it would die. It would also do a chugging/skipping while driving at low rpm as if it was trying to die out again. I noticed the chugging/skipping was worse idleing in drive and reverse than in park.

From here, I changed the Idle Air Control Valve, and topped off coolant. Check engine light came on around this point and threw a code 42 which the manual says is 'Electronic Spark Timing'. I checked the connections between the ICM and the ECM with a multimeter for continuity while stress testing the cable as best as I could and it seemed to be able to pass signal. Did the same for the pigtail from the ICM to the coil and the cable/connector seems fine.

I finally took it to a mechanic friend. On the way over to his shop it seemed to drive and idle totally fine. Once I arrived, I let it idle in the parking lot for a bit and started poking/moving some of the wires to the ICM. After touching the group of two cables, it started chugging/skipping again and died. From here I left it with my mechanic friend who replaced a small length of cable going to the group of 4 wires on the ICM, and also re aligned the timing. This got rid of the check engine light and the chugging seemed to go away. He took it for a test drive and said it was all good.

I picked it up this morning, it drove perfectly for about 15 miles. I was stopped at a light when I noticed it slightly lurch forward. I noticed the gas was very low and hoped it had something to do with that. After I filled up, as soon as I pulled out from the gas station it stalled and died. Once I started it up again the chugging/skipping was back, allong with an occasional loud metallic clank/knock that sounds like its coming from somewhere near the engine. It seems to happen too intermittently to pin point exactly where its coming from.

Any and all advice is on next steps or things to look for is greatly appreciated.

 

Did you put the heat transfer putty under the ignition control module?

 

Also since it sounds like an ignition issue it's always a good idea to spend a little bit of time diagnosing in the dark with all of the lights out. If there are any glowing purple ants crawling over something replace that.

 

Thanks for the reply

I did put the heat protection stuff under the ICM

Also not sure exactly what you mean by glowing purple ants?

Thanks

 

If you see the glowing purple ants you will know what I am talking about. You will see them if you are leaking high voltage from something like the coil. If it has a crack it will look like there are glowing purple ants crawling along the side of it. With all of the dirt and grime on a dark colored part to begin with it is hard to see a carbon trace on a hairline crack. Much easier to see when it's running. I had the same thing on my old TBI S10.