2001 Chev 2500HD - 8.1L /Allison Stalls

[RC Performance]

I've got an 01 2500hd with an 8.1L and an Allison. I've got an intermittant engine stall. First start up in the morning drive 10 miles and the engine dies for a few seconds and restarts on it's own. The problem does not return for the rest of the day. Has anybody run into this? No dtc's cam and crank sensors were replaced by GM.

[steven kiser]

are you sure there are no codes. i've gotten codes in global and not in the normal way. i think this is going to get wores and worse and you'll find injector pump is on the way out. i'll dubble check and post monday.

[RC Performance]

Yes, I'm positive no codes and the fuel pump seems to be fine (502 Gas engine). I'm thinking there is a faulty driver in the ecm. When it does stall it takes about 5 seconds to restart when the torque converter stays locked. There is nothing out of the ordinary showing in the datalogs.

[steven kiser]

"when the torque converter stays locked".
that may be your answer. if a converter stays locked during a stop it will stall the engine. it's like coming to a stop in a stardard transmission driven car and not depressing the clutch. see if the converter disenguages when the brake pedal is depressed. there may be a signal issue here. check the harness where it passes through the transmission. it may be melted. i've seen this happen from people resting their foot on the brake pedal for long period of times while ideling. it does seem to me that the issue is the converter staying in lock up. good luck. just a poont to make here. the tip of the converter staying locked seems as it was posted as an after thought. giving all information in a post for repair is essential. i've seen many issues solved because on the third or fourth post more information is added...........................just a tip, not a critisizm.

[RC Performance]

No sweat. It doesn't stall at a stop, it does it while cruising at highway speed. What's odd is it usually only happens once a day when starting out.The truck is at highway speed within 2 minutes of start up,drive it almost exactly 10 miles at 75 mph, and it stalls for 5 seconds or so and then restarts. I'm thinking it's a circuit that is affected only in open loop. I may just swap out the ecm as a test. (I hate changing parts).

[steven kiser]

may be picking up air in the fuel system. seems like timing may be right for an air pocket.

[RC Performance]

That sounds reasonable.

[berrelauto]

My truck did the same thing , No codes and it was the crank sensor It also happened on 2 other customers trucks

Dale

[steven kiser]

have you taken a movie of what's happening when it does this? this is an ideal issue for it. it's a constant. i've taken movies of what's going on and loaded it into my main diagnostic scope and done a frame by frame. you may see something as far stretched as a spike in the alternator right before it stumbles. i've solved a few intermitant issues on gm's by putting a resistor at the alternator plug. i think you're right in line with the loop thought. i wonder what would in fact happen if the alternator is spiking all the time and just as the computer switches to open loop it allows the spike in and momentarily shuts down. a reburn may resolve this issue as well.