Negative torque values at idle

[Martinle]

My car - 2017 ZL1 M6 - has been idling high since I let her out of the garage this spring. Put her on the dyno and was told I have negative torque values at idle which probably is the cause of my high idle. My car has only been tuned by Jannetty Racing. I can think of no reason for them to put those values in, but they (values) cannot change by themselves, as I've been told.

Any thought would be appreciated.

[Ben Charles]

If it’s too negative it will idle high… may just need to bring up the tq, the DD table can cause this as well

[Ben Charles]

Could also be a Vac leak, tune may be fine…

[GHuggins]

Without a log or file it's hard to say, but you should have negative timing too. If you have negative timing and negative torque then it's trying it's best to bring the idle down.

As Ben stated - vac leak or may even need the throttle relearned if the battery was dead/unhooked. I'm told by the engineer that helped design the torque modeling that these things will "learn" up to 30 Nm one way or the other back to whichever model is the highest.

Negative torque at idle isn't a bad thing - especially with a manual. Ideally you want it around 0 +/- 10 with a large cam.