I've been playing around with the closed-loop idle control for the past week or so, and i've gotten it to wind itself up a few times by engine-braking down into the region where the closed-loop idle tries to operate. The code then keeps increasing the dc, and when I push the clutch in the DC is high enough that it causes the engine to rev up above the RPM point at which it closes the valve and stores the very high DC as the most recent DC that it'll start at next time the engine enters closed-loop idle. Then, as RPMs fall since the valve was closing, it goes back into closed loop, the idle valve opens up to the high DC value, and the RPMs shoot back up out of the closed-loop operating region. It will just keep doing this until you cycle power to the MS. A similar thing happens if you engine-brake down into the region, and then press the gas to accelerate out; it will just happen next time you try to idle.

My first (and probably more difficult to implement) thought was to have the closed loop idle only operate if an input pin is connected ground (by wiring the clutch switch in parallel with the neutral switch, with a diode in there so you dont activate launch control in neutral) That way the engine braking problem would be avoided all together.

Probably a quicker way of accomplishing the same thing would be to have a choice of whether to use the current system of taking the last DC and adding the DC adder to it, or taking a user-specified DC as the default to start at each time you enter closed-loop control.

 

What are your PID lockout settings set to?

Also, you should have the RPM adder set pretty low, like 100-200 rpms. That way you won't get into a situation where you can engine brake down that low.

Ken

 

I have the RPM adder set to 250 right now (idle RPM is 800 so that its far enough above the secondary cutoff that I can see it in almost all situations). Higher values of this seemed to help mitigate oscillations. I also tend to leave it in gear heading up to stoplights, going downhill etc, and do a bit of creeping/stop-go driving between 700 and 1500 RPM in the highest gear I can.

Anywho, all the settings are:
Freq : 200
Cranking (dc) : 90
Minimum (dc) : 0
Closed (dc) : 0
---------------------------
Fast Idle Temp (C) : 0
Slow Idle Temp (C): 27
Fast Idle Speed (RPM): 1500
Slow Idle Speed (RPM): 800
----------------------------
TPS threshold (ADC): 32 (fully closed is 29-30, fully open is 210 or so)
Idle Activation Adder (RPM): 250
Dashpot Settle Time (x0.01 sec): 30
Dashpot Adder (dc): 2
----------------------------
Deadband (+/- RPM): 40
Upper Limit (hi RPM): 200
Lower Limit (lo RPM): 80
Fast Recovery (x0.01 sec): 5
Slow Recovery (x 0.01 sec): 30
-----------------------------
Closure Speed (x0.01 sec): 5
Startup Delay (x0.01 sec): 50

 

I've got some new changes coming for closed loop idle that should help some of the issues people are having... although you'll have to change your P, I, and D settings. You should be able to raise them considerably, and set lower control intervals as well, which should help with responsiveness.

Ken