Idle Control Tuning

I just added A/C to my LS2 Engine. The engine is Naturally Aspirated, and has a 6 Speed Manual Transmission, It is swapped into a 1959 GMC 100. I am running the ECM in Speed Density Mode (by putting MAF into fault), as it has a large cam and the intake air piping and MAF are set up with several turns and not alot of straight runs for the MAF.

When I come out of gear, into neutral, coming up to a stop light the engine RPM starts swinging around and can sometimes even stall. This only happens when I have the A/C on. If I turn the A/C off, I have no issues.

What suggestions do you have on how resolve this issue? I use HP Tuners to tune my ECM.

Thank you.

Hi Andy,

Does HP tuners ECU have capability to detect and compensate for AC load?