New to me 2000 K2500 missing at idle, occasional stalls

[Nicman201]

Damn. After a week and a half and like 6 full tanks later of driving I was coasting to a stop at a light and it started chugging. Torque shows that cylinder 2 has a steady misfire. It's bad enough where there's some vibration when accelerating from a stop but then it seems ok at cruising speed.

 

[Nicman201]

I'm hoping it's just a bad injector. I jumpered the fuel pump relay and could hear gas trickling inside the intake.

 

[wirlybird]

Might be a long shot but what about the mass airflow sensor? I know on my Tahoe when it is going out it creates all kinds of issues.
Most apparent are stumbling/cutting out while trying to accelerate. Rough running and bad idle.

Another time ran bad and I suspected the Mass airflow sensor it turned out to be a bad distributor cap.

 

[Supercharged111]

Might be a long shot but what about the mass airflow sensor? I know on my Tahoe when it is going out it creates all kinds of issues.
Most apparent are stumbling/cutting out while trying to accelerate. Rough running and bad idle.

Another time ran bad and I suspected the Mass airflow sensor it turned out to be a bad distributor cap.

That one's super easy to rule out: unplug the MAF, go for a drive, and see if it got better.

 

[Nicman201]

That one's super easy to rule out: unplug the MAF, go for a drive, and see if it got better.

I just tried this still chugging but torque not showing misfires with it running while MAF unplugged

 

[wirlybird]

That one's super easy to rule out: unplug the MAF, go for a drive, and see if it got better.

I tried unplugging mine and it didn't help much at all or I guess nothing really changed. Replaced the MAF and the truck was back to good.
I don't know why unplugging didn't change it.
I do remember though that once I replaced the MAF it ran better right away but took a little while driving for things to really get back to normal.

 

[Tp86k10]

Ok. I recently acquired a 2000 k3500, 454 4l80e. 77k miles. I was having similar issues. Mine would idle erratic and occasionally stall, but only when warm. Cold it ran great. No codes, no ses light. Went through all of the fuel system (injectors, pres regulator, filter), did a full tune up, plenum gaskets. Monitor with my nemisys scanner. Could see nothing that would indicate the problem. Cam retard set at 0°. Ended up being that the torque converter was partially locking up at idle. Through some research I found it was a somewhat common issue on the 4l80s. Sonnax sells a valve that fixed it right up. And since I planned to drop the pan anyways for a trans service, it worked out well. Valve is easily accessible once pan is off, changed out in 5 minutes. Night and day difference. Part number is 34200-14k, lube regulated pressure regulator valve (aka line to lube valve). This may not be the same issue your having but man, it sounds very familiar.... Hope this was of help!

 

[Schurkey]

Ended up being that the torque converter was partially locking up at idle. Through some research I found it was a somewhat common issue on the 4l80s. Sonnax sells a valve that fixed it right up.

Woof. That would never have occurred to me. Congratulations on finding that...and letting us know about it.