Need Help with Idle on LS3 with 6L80E (Aggressive Cam)

[spektr44]

I have a 1968 Corvette, LS3 with automatic transmission 6L80E. We just fired up the engine for the first time in 10 years as a project. The car has an aggressive cam but we lost all paperwork on what kind of Cam it is. We bumped up the idle to 850-900 RPM and increased the airflow a bit. The car idles more or less OK. It does well at High RPM, however, after you let the gas pedal go, the RPM drops to 400-500 and the engine stalls.

I am new to tuning LS motors. So, any guidance is appreciated. I enclosed the logs and the tune. Please advise.


stok 12_08_Mod1.hptRun Log 12_09_2023.hpl

[Cringer]

I have a 1968 Corvette, LS3 with automatic transmission 6L80E. We just fired up the engine for the first time in 10 years as a project. The car has an aggressive cam but we lost all paperwork on what kind of Cam it is. We bumped up the idle to 850-900 RPM and increased the airflow a bit. The car idles more or less OK. It does well at High RPM, however, after you let the gas pedal go, the RPM drops to 400-500 and the engine stalls.

I am new to tuning LS motors. So, any guidance is appreciated. I enclosed the logs and the tune. Please advise.


stok 12_08_Mod1.hptRun Log 12_09_2023.hpl

The log file is very sparse. You need to add quite few more PIDs IMHO to properly tune idle. I made an instructional idle video, and the the video description has a link to the scanner config. https://youtu.be/TVsFcMHySAc

There are quite a few commanded idle tables in the ECM and yours all disagree with each other. I have fixed that disagreement and commanded an idle of 825 rpms. The good news is that the idle appears to be pretty stable. I made two tunes for you to try out. A basic one that fixes the commanded idle disagreement between the tables, and one that also makes tweaks to idle air and spark. Hopefully this helps.

Fixed conflicting idle rpms only (all set to 825):
stok 12_08_Mod1 - Cringer - basic RPM changes only.hpt

Fixed conflicting idle rpms, plus a few changes to idle air and spark:
stok 12_08_Mod1 - Cringer.hpt

[spektr44]

Thank you so much! We tried both Tunes. The idle sounded great. However, after we revved up the engine and allowed it to return to idle, the engine stalled right away. We will watch your video, collect additional data points, and share the logs.