Short version: I want my IAC to stay open with throttle application, then slowly taper back down to idle when lifting off.
Long version: Hi guys, I use HPtuners but have found this forum to generally be more helpful than the HPT forum, so I thought I'd join up and ask here!
I'm having some trouble around idle. It doesn't want to catch the idle after giving it a rev, I've got it pretty close, however it's still not 'right'. I've scanned a mates car for live data, 1 bar MAF enhanced, car is AUTO, unknown cam specs, however from listening to it at idle, it sounds as though it has more overlap than mine. His tune still retains closed loop fueling at idle, almost stock PID's for idle control (just slightly softened Integral values) and fairly aggressive under and overspeed timing. (9* each way). It runs and drives great.
My tune is 3bar SD, has fairly hacked up PID's, open loop fueling at idle, and idle spark tables cut right back to stop idle swings. It idles rock steady at 800, but if I give it a rev, on return to idle it drops below target idle speed and then picks back up. It also has a bit of oscillation when I'm slowly letting the clutch out with small throttle openings. I'm confident my Base Running Airflow is very close, I did the Russ K idle config a while back. My cam is a 227/223@115 for reference.
Now, in the logs of mine and my mates car, I notice my mates IAC position goes up with small throttle applications, and SLOWLY comes back down to idle nicely, mine does weird things with light throttle like going to 0, then spiking back up, then back to 0. With the tune I have now, if I give it a rev, the IAC goes to near 0, then spikes up to about 80 just as its returning to idle, before settling back into its normal idle range values (38ish steps).
What is causing our two IAC's to act so differently? I've tried all manner of PID configurations, from all stock, to slightly softening each individually, to softening all of them, tried increasing them etc, tried adding in throttle followers, tried running massive amounts of Base Running air flow to try and make it catch really high, then use the PIDs to slowly bring it back down but nothing seems to work. Anything I do results in it dropping to 400ish RPM, then springing back up. Any help would be greatly appreciated.
Cheers, Ben