I’m just starting to delve into tuning, and I’m trying to figure out why my AFRs are fluctuating, even at idle, when I would expect them to be fairly stable. Attached is my .msq and a log of the car coming up to temp at idle.

Car is 2000 with VVT swap with 01-05 injectors, run by a Rev-built MS3. I recently installed LS2 truck coils wired sequentially. I used Andrew’s numbers for the dwell correction and table (post #373 @ https://www.miataturbo.net/build-thr...-84579/page19/). My wideband is an LC-2 (just recalibrated) with a CAN interface to the MS3. I also installed recently an AFR gauge, which closely mirrors the AFRs I’m seeing in Tunerstudio. I thought there could be some interference on the O2 sensor ground (which only the AFR gauge shares), but even when the gauge is disconnected from the ground there is no change to the AFRs.

Finally, my idle is fluctuating and higher than it should be. I’m thinking this is related to not being able to dial in my AFRs. I’ve set it to idle at ~900 RPMs in the closed-loop idle target once warmed up, but it’s idling over 1000 RPMs.

Do you guys think this is just a tuning issue or do I need to start looking at my install and/or faulty sensors?

Thanks much!

Bryan