L83 Bank 1 Lean/Bank 2 Rich only at idle

[gwvisegrip]

New User. 2015 Chevy Silverado, 5.3L, 150K, Gwatney performance DOD Delete kit installed and programmed with stage 1 cam. New upstream and downstream O2 sensors. MAF and VVE Fuel Trims within 1-2%. Still have a lopey, stumbly idle.
I will upload scan file shortly.

Running down the road or around town, O2 sensors on/off track each other perfectly and LTFT are spot on.
When Idling warm it is slightly rough. Not really searching for timing BUT Bank 1 Upstream O2 is bottomed out Lean and Bank 2 Upstream is topped out Rich when in closed loop. As soon as I force Open Loop, Idle is all smoothed out and both O2's are rich.

I've tested for exhaust leaks and intake leaks and found none. I've also tested the CATs (Temp Test) and found no obvious issues.

I'm leaning toward a slightly plugged Fuel Injector (I did not replace them when I rebuilt the motor in November) but I'm at a loss here. I have tested them by turning them off at idle and they do cause a distinct miss.

Also, the Cam has an 11% Fuel lobe increase and the motor has a distinct sewing machine TICK to it and is DEFINITELY the Fuel Pump (I used a mechanic's stethoscope for this) not valve train. Anyone else had this issue? It's annoying as hell. May need to put a louder muffler on it to mask the noise but I like it quiet for now. (Getting older)

Thank you in advance for any advice. I've done all the work and I'm doing the programming so I'm the target. LOL.....

[TriPinTaZ]

Stock manifolds or headers?

[gwvisegrip]

Stock manifolds, stock exhaust.

[gwvisegrip]

Reset LTFT today and drove a bunch. Seems better but will still fall into this pattern at idle at times. Got a tank of fuel with Lucas injector cleaner now.

[D-TUNED]

you might want to check valve sealing if the problem is only at idle. 02 sensors are okay for engine performance however are very dumb they they only detect oxygen. so a miss fire at idle will seem like a lean condition but its only bc the cylinders/cylinders effected are pumping oxygen and partial raw fuel. and another thought just by looking at dat is the upstream 02s could be crossed however unplugging the down stream 02 sensors would be a good diag tool. unplug them and see if it helps

[FastV]

New User. 2015 Chevy Silverado, 5.3L, 150K, Gwatney performance DOD Delete kit installed and programmed with stage 1 cam. New upstream and downstream O2 sensors. MAF and VVE Fuel Trims within 1-2%. Still have a lopey, stumbly idle.
I will upload scan file shortly.

Running down the road or around town, O2 sensors on/off track each other perfectly and LTFT are spot on.
When Idling warm it is slightly rough. Not really searching for timing BUT Bank 1 Upstream O2 is bottomed out Lean and Bank 2 Upstream is topped out Rich when in closed loop. As soon as I force Open Loop, Idle is all smoothed out and both O2's are rich.

I've tested for exhaust leaks and intake leaks and found none. I've also tested the CATs (Temp Test) and found no obvious issues.

I'm leaning toward a slightly plugged Fuel Injector (I did not replace them when I rebuilt the motor in November) but I'm at a loss here. I have tested them by turning them off at idle and they do cause a distinct miss.

Also, the Cam has an 11% Fuel lobe increase and the motor has a distinct sewing machine TICK to it and is DEFINITELY the Fuel Pump (I used a mechanic's stethoscope for this) not valve train. Anyone else had this issue? It's annoying as hell. May need to put a louder muffler on it to mask the noise but I like it quiet for now. (Getting older)

Thank you in advance for any advice. I've done all the work and I'm doing the programming so I'm the target. LOL.....

Make sure the 02's aren't on the wrong banks...