What triggers, PID closed loop idle

[nathanhardy]

What settings tell the computer to switch over to pid closed loop idle control it’s not obvious stated in tuner studio

[rickb794]

I think it's always on.

[nathanhardy]

I’ll post a log tmrw but I get this random hang up to where the car gets stuck in a high idle and it take a while to drop down to closed loop..

[nathanhardy]

The last time it did it it was actually idling great then without touching anything it shot up to 2000 rpm where it usually goes when it does it.. I couldn’t tell what changed and like always I wasn’t logging

[ShirtUser]

Most of the time, for me, when the motor seems to be stuck on a high idle and doesn't come down, it's because the Overrun MAP threshold is set too high.

Another issue can be if your initial IAC open value is too big so the initial idle RPM is far above the target, and then the PID settings are aggressive so it tries to adjust quickly, causing the falling RPM to be faster than your slow deceleration threshold, which will kick it out of closed loop. In this case, the idle will start to drop and then go back to the high RPM, then start to drop, and repeat.

Talking about MS3 1.5.2, in order for closed loop idle to engage, the following conditions have to be met:

-Current MAP must be above Overrun MAP threshold even if you have overrun fuel cut turned off (on Engine State Settings page)
-Current TPS position must be below Throttle closed TPS threshold (on Engine State Settings page)
-Current speed must be below VSS Threshold if you have "Use VSS" enabled (on Engine State Settings page)
-Current RPMdot must be below the Slow acceleration threshold (on Engine State Settings page)
-Current RPMdot must be above the Slow deceleration threshold (on Engine State Settings page)
-Current TPS position must be below the Wide-open throttle threshold (on Engine State Settings page)
-Algorithm must be set to "Closed-loop" (on the Idle Control page)
-Time since above conditions are met must be longer than the PID Delay (on Closed-Loop Idle Settings)


I found that using the Closed-Loop Idle Initial Values table and "Use Last Value or Table" set to "Use initial value table" works best for me. You can use last result, but it gives me inconsistent results on my motor. I found using MAT for the lookup table works well.

If your RPMs are sticking really high when you let off of the throttle, it's because the initial value it tries to go to is too open.

Obviously, a log will be definitive. But based on your description of it idling ok and then shooting up to 2k without touching anything, I'm going to guess that your Overrun MAP threshold is too high.

A log would be best

[shiftin04]

I would imagine you can set up the SD card to watch the return to idle stuff. That way you can pull the log when it randomly happens.

[nathanhardy]

Most of the time, for me, when the motor seems to be stuck on a high idle and doesn't come down, it's because the Overrun MAP threshold is set too high.

Another issue can be if your initial IAC open value is too big so the initial idle RPM is far above the target, and then the PID settings are aggressive so it tries to adjust quickly, causing the falling RPM to be faster than your slow deceleration threshold, which will kick it out of closed loop. In this case, the idle will start to drop and then go back to the high RPM, then start to drop, and repeat.

Talking about MS3 1.5.2, in order for closed loop idle to engage, the following conditions have to be met:

-Current MAP must be above Overrun MAP threshold even if you have overrun fuel cut turned off (on Engine State Settings page)
-Current TPS position must be below Throttle closed TPS threshold (on Engine State Settings page)
-Current speed must be below VSS Threshold if you have "Use VSS" enabled (on Engine State Settings page)
-Current RPMdot must be below the Slow acceleration threshold (on Engine State Settings page)
-Current RPMdot must be above the Slow deceleration threshold (on Engine State Settings page)
-Current TPS position must be below the Wide-open throttle threshold (on Engine State Settings page)
-Algorithm must be set to "Closed-loop" (on the Idle Control page)
-Time since above conditions are met must be longer than the PID Delay (on Closed-Loop Idle Settings)


I found that using the Closed-Loop Idle Initial Values table and "Use Last Value or Table" set to "Use initial value table" works best for me. You can use last result, but it gives me inconsistent results on my motor. I found using MAT for the lookup table works well.

If your RPMs are sticking really high when you let off of the throttle, it's because the initial value it tries to go to is too open.

Obviously, a log will be definitive. But based on your description of it idling ok and then shooting up to 2k without touching anything, I'm going to guess that your Overrun MAP threshold is too high.

A log would be best

Where is this setting?

Time since above conditions are met must be longer than the PID Delay (on Closed-Loop Idle Settings)

[ShirtUser]

Startup/Idle menu -> Closed-Loop Idle Settings -> PID Delay(s)

[nathanhardy]

The table where you select where the valve is helped but it is still not perfect, I need to tweak those tonight on my drive home.......