[ZLRob]

Originally Posted by radz28

Would it be easy to describe or characterize what you have changed for these mods'? I saw you mention Flex-tuned, so I imagine your car is tuned. If you haven't looked already, I might also see if your Virtual Torque tables have been adjusted. It's hard to say not being able to see the tune or a scan, but if you're tuner touched anything air flow related, it could be your VTT idle areas could have moved around. I doubt your mods' might require that, but in the event someone changed them from stock, it could be that's something to look into. Again - I wouldn't think that would be necessary for your list of mods', but I wouldn't know what your tuner did or didn't touch.

VTT will influence idle. A calibrator who helped me said that he liked seeing TMA pull around 10* of timing at idle, just so it's doing it's job, and had enough timing swing to add or pull torque to achieve the desired idle speed. Of course, there needs to be a minimum advance so you don't melt cats and such, but I'm just saying VTT is very important for idle, and if that's not shaped correctly, you can have some naughty behavior.

Also - have your Driver Demand Increasing/Decreasing Immediate/Predicted torque rates been moved around or anything? There's a TUTD function in those, too.

What is TUTD?

The Driver Demand tables were modified by someone who owned it before I did but I set them back to stock. The same issue occurs. I just checked the Virtual Torque and even the Virtual VE tables and found they have been untouched compared to the OE tune stock file.

You know, when I see the issue happening I see TMA pulling as much as 11.5 degrees before it ever gets to idle. When that occurs I see timing jump from 10 degrees to 14.2 degrees which is not terrible, but something is up for sure. I'll attach a screenshot of the event so you can see what the primary event looks like.

Originally Posted by raptor5244

FWIW, my 2021 ZL1 was bone stock and did what you describe.

It's frustrating isn't it? The issue is being narrowed down on mine and it has been found that it is Torque Management making the PCM pull too much timing for the brief moment the issue occurs and it is evidenced by a sharp spikes in the Torque Management and timing advance graphs the moment it happens. We can't figure out why it's happening though.