Deceleration Stumble

[Beeffajitas]

So I've got this condition where the motor stumbles only on decel. I have the Torque app and I can see the Ignition Timing go to zero when it happens. I can't tell if this means the timing is really going to zero, or if the ignition is dropping out altogether. It's a random thing, doesn't happen all the time. It started happening on the black box ecu and it's still doing it on the 411 I swapped in. I changed the ignition module for something else a little while ago, so that SHOULD be good, but who knows these days.

I'm starting to think it's the dizzy. It's the only thing I can think of that would experience any change between accel and decel. I also haven't changed it, so it's unknown condition at this point.

If anyone had a similar condition, please chime in.

 

[cemeteryxgates45]

Not sure if the vortec/411 has this feature but my tbi has a decel mode built into it so that when you let off it looks for brake input after 40mph and if it doesn't see any it'll cut the ignition out and start engine braking and it'll cut it for 2-5 seconds then come back to keep the engine running and it'll do it untill the speed is below 25 or there brake input

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[Beeffajitas]

That kinda sounds like it, but man is it annoying. I had a half-ton 350 vortec before, and I don't remember it doing this.