Hey everyone, Now that I won't be needing the AC for winter I've decided to drop my idle back to the <1K range but something is off. Basically I have to lower my Minimum(dc) to 9 just to get the car under 1K RPM at idle. I thought it could be a vacuum leak but I've checked with smoke and starter fluid and havent been able to locate anything. Unfortunately when I set Closed(dc) and Minimum(dc) to 9 to lower the idle the car stalls whenever I come to a stop. My idle adjustment screw is closed all the way because if I open it any I have to lower the Minimum and Closed to maintain a decent idle speed which seems to exacerbate the stalling issue.

My car is a 1997 Mazda Miata with a JRSC kit (TB before the blower)

My settings are

Minimum(dc) - 9
Closed(dc) - 9
Slow Idle Speed - 850
TPS Threshold - 25
Idle Activation - 700
Dashpot Settle - 75
Dashpot Adder - 1

Upper Limit - 200
Lower Limit - 50
Fast Recovery - 3
Slow Recovery - 39
Closure Speed - 2

Any advice would be appriciated. I've just noticed that most people have Minimum(dc) around 20-25. Would the low Minimum(dc) have anything to do with the stalling issues?

 

Hail Mary Bump

 

Have you tried increasing the Dashpot Adder value? This briefly adds more duty cycle when the throttle is snapped closed.

 

I raised it to 4 with no effect.

Yesterday I disconnected the IAC and manually set idle at 800. Then I plugged it back in and adjusted the values enough to keep it from stalling (or oscillating wildly) and I've managed to get a fairly stable idle at ~1050. If I lower anything by even a point it droops to ~300 and then sways like crazy. I changed my fast idle RPM settings but that either led to a stall or more sway.

 

What is your voltage at idle? What are your AFRs? Have you considered a dual TB setup? Try forcing it rich at idle.

 

Voltage is around 13. I did run it rich which didn't seem to help but when I pulled spark it calmed it down a bit. My spark advance is 9 in the box where it usually idles and 10 surrounding it.

I havent considered dual TB but I am thinking about moving the TB back to stock position and putting a blow off valve on the blower. I think part of my problem is that when the TB closes there's still a ton of air in the intercooler piping that it can't quite compensate for.