choff

01 express 3500 5.7 85K original owner
1st lower intake gasket replacement around 42K. Felpro hadn't made the current best option (MS 92000T or whatever the exact number is). Work was performed by a friend that worked at the dealership in my shop. Had no issues until a few months ago. All the tell-tale signs showed up and having watched him do it the first time decided to tackle it myself.

Really took my time and labeled everything, made notes and took pictures. Spent about thirty hours all told. Had lots of fouling, carbon build up in the plenum and intake. Globby & milky oil in the valley and on top the heads. Cleaned, cleaned, cleaned.

Put it all back together waited about ten hours for the silicon at the front and back of the block before I turned it over to see if I got the distributor back in correctly. It fired right up ran very very slightly rough for 2 or 3 seconds and then it just purred. I shut it off, got stuff out of the way opened the shop door and drove it less than a 1/4 mile to make sure 0-60mph was OK.

Got up this morning it was about 28 outside. Fired right up. Drove the truck into the city (25 miles) to go to work. No issues. Ran like a champ, felt like it was a little more responsive. I pulled into the parking lot and left it running. Got out looked underneath for leaks. Popped the hood looked for leaks. Everything dry as a bone. My buddy that stopped by to help me set the intake back in walked up and we were just chatting about the repair when the engine shut of as if someone turned the key off. Just like that. Now it wont start. Towed back to shop.

The codes I got from my cheap scanner said misfire cylinder 3 and faulty crank sensor.

Not getting a spark... well I got an intermittent off the coil, then bought new coil and had the ICM tested at auto zone. Put in new Crank Pos Sensor. No dice. Pulled cap to check, distributor is still turning

What happened? What did I possibly do wrong?

Additional work I did because I was there and or it needed it = New cap and rotor, new PCV & oil pressure sensor (dropped a hammer on it on the workbench). O-rings on the fuel lines, upper intake, TB gasket & valve cover gasket.

help please

choff

Seems a little poetic that it was the part I let the guy at auto zone talk me out of buying. He put it on the diagnostic tester and ran the test 6 times. Each test showed the ICM was just fine. Went to O' Reilly's and two of those guys tried to talk me out of buying it. Fortuneatly, I had just gotten off the phone with an old friend that used to be a GM certified wrench turner who told me that those testers are unreliable.