Idle +150 RPMS Over Commanded

[blsnelling]

For years, I haven't been able to achieve the idle RPMs like I wanted in my truck. Finally, I spent a couple hours this evening playing with the tune. No matter what I do, something is commanding the idle RPM to be 150 RPMs higher than I have commanded in the Desired Idle Speeds table. This is true for the RPMs in all four columns. I played with every table under Idle -> General. I finally gave up and lowered all numbers in that table by 150 and it finally idles where I want it to. In other words, I have to command an In P/N A/C Off RPM of 500 in order for it to idle at 650 RPMs. What gives?

On another note, I've had issues with the A/C not wanting to run at idle ever since I put this mildly cammed LQ4 in here years ago. That's why you see all my A/C on RPMs as high as they are. Even at 1100 RPMs, it still sometimes doesn't want to keep the compressor on. I can't find anything in the tune that would cause this. Any ideas?

[joecar]

Can you post before and after tunes...

[blsnelling]

This is the tune from before I figured out it was +150. My goal was to idle at 650 only when in idle and no AC. If we can figure out why the AC compressor doesn't want to run at normal idle, I'll bring the others down to something like 800.

FYI, freon is not low and pressure cycling switch has been replaced twice with an AC Delco part.

Truck_09_19_2022.ctz

[Lonnies Performance]

Your stall saver rpm is set to 800 across the board..

It should be typically 100-150 rpm below the desired speed.
This makes it kick in at 800 when you only want 650.

Not sure of the overall effect, but my AC clutch drops out when the rpm goes below this setting to reduce engine load.
I never set the value above the actual rpm, so I'm not sure if it will also bump the idle speed.

B4603 is where you should set the idle speed.
Try making these all 650rpm & set the stall saver to about 150 below the RPM value adjacent to that cell.

[blsnelling]

Not sure of the overall effect, but my AC clutch drops out when the rpm goes below this setting to reduce engine load.
I never set the value above the actual rpm, so I'm not sure if it will also bump the idle speed.

Very interesting.