TheMiataOwner

Hi everyone, I'm having a bit of closed loop idle tuning woes. I used to have an issue where when the car was hot, if I blipped the throttle, there's a good chance with accessories on that when the RPMs come back down, my car will bog down and die. Sometimes it would bog down but not enough to die.

I have finally got it to the point where I can't kill it by letting the RPMs drop after blipping the throttle, but I'm still having a few issues. For 1, now my idle settings are making my RPMs oscillate when the RPMs come back down after letting off the throttle (starts at the beginning of log attached). I want to say this is due to my idle control PID settings, but I haven't had this issue before and I made pretty minor changes to those settings. I don't believe there's a vacuum leak as my idle MAP hovers around 32-34 kPa.

Another issue is that my RPMs also hang now after I let off the throttle and then come down to begin the oscillation. Furthermore, when it starts to settle after the oscillation, the RPMs are way too high, higher than my target RPMs. I suspect it is because my initial value table isn't right, but let me know if I'm wrong or if there's more to it.

Finally, probably the most minor issue compared to the others, but if I quickly blip the throttle at idle, my RPMs will bog down and then climb up, which you can see me do in the log after 200 seconds.

Here are things I've done: set my base idle (idle valve at 0% duty and fixed advance) when fully warmed up at 750RPM. My lowest target warm RPM is currently set to 900RPM, but I want it to be 850RPM. I have the idle VE table turned on, but I suspect I haven't been able to tune it well since I can't artificially get it to go to a higher load at specific RPMs. In terms of other idle settings, I've tried to incorporate the initial value table, messed with CL idle settings, idle control settings, idle advance settings, and RPM timing corrections. I nabbed Braineack's idle RPM timing correction settings and I believe his accel enrichment settings as well, which seem to help it recover faster from bogging down after coming into idle.

TLDR: Need help idle tuning... Idle RPM oscillates lots before settling, hangs RPM after letting off throttle while stationary, bogs down when letting off throttle and RPMs go back down, and bogs down when quickly pressing throttle.

My setup is a 2001 engine in my 1991, running an MS3 basic, GM IAT, NB1 intake manifold, and Bosch EV14 700CC injectors. VVT is currently disconnected to hopefully help with idle tuning.

What pointers do you guys have for me? Tune and log are attached below.