Won't run after warm up but fires

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Joined: Sun Feb 24, 2019 11:03 am

Won't run after warm up but fires

Unread post by PatrickABCD1234 » Sun Feb 24, 2019 11:33 am

2000 GM 3800 starts normally when cold but sputters and dies after warm up. Will fire but not run again until cool. I've read many posts about this but no solution. I promise to post my solution when I get it figured out, with some help. : )

When warmed up, not starting: Fuel 48psi, spark jumps 35mm gap at end of all plug wires. Cam pulses once per 2 crank revolutions and crank 3/18 pulses are normal 5v also(rotating by hand while probing ICM connector, injectors unplugged). DTC is random misfire. ECT, IAT, TPS, MAF, MAP read normal values. Unplugging MAF makes no change.

When hot it will start and run if reved up while cranking but misfires and will die if rpm gets to low.

From what I have read a bad crank sensor usually causes no spark when it heats up. After the car warms up a bit then died I get pulses from it and spark. Does it seem like the ICM? Or maybe CPU? Thanks!