Please clarify closed loop idle settings.

[460stang]

I got the PID settings no problem, with a little help from Wikipedia. I think I have some of the other settings figured, please correct errors and fill in the blanks as required.

Idle Open duty and Closed duty- seems to define the responsive range of the idle motor.

Idle activator RPM- ????

Idle activator TPS threshold- ????

Min duty or Max steps for PID- seems to define how low PID can take the idle.

PID delay- How long PID waits to begin action, waits after what event???

Proportional Gain - Larger typically means faster response since the larger the error, the larger the feedback to compensate. An excessively large proportional gain will lead to idle instability.

Integral Gain - Larger implies steady state errors are eliminated quicker. The trade-off is larger overshoot: any negative error integrated during transient response must be integrated away by positive error before we reach steady state.

Derivative Gain - Larger decreases overshoot, but slows down transient response and may lead to instability.

PID lockout RPMDOT - I assume that if I am in a accel over the amount specified PID stops, not sure for what purpose?

PID lockout max decel load - Same as above in the opposite direction?

[Keithg]

I got the PID settings no problem, with a little help from Wikipedia. I think I have some of the other settings figured, please correct errors and fill in the blanks as required.

Idle Open duty and Closed duty- seems to define the responsive range of the idle motor.

Open is slightly above the highest duty cycle you will ever see - hot day, A/C on, lights, fans, warm engine.
Closed The duty cycle when the valve is closed. This is usually 0, but on some Bosch valves it is ~25%.

Idle activator RPM

How many rpm above the rpm set point that you want it to engage. As RPMs drop, when do you want it to take over. So, if warm idle is 900 and you want it to take over at 1200, the activator should be 300

Idle activator TPS threshold

Set this just below the TPS % when the throttle is on its stop (no pressure on the throttle pedal)

Min duty or Max steps for PID- seems to define how low PID can take the idle.

This is slightly below the lowest duty cycle you will ever see - cold day, no accessory load.

PID delay- How long PID waits to begin action, waits after what event???

this is 'how long' the code holds the duty cycle at the recovery value before it will allow PID to engage. Recovery value is the last known good duty cycle plus the 'dashpot adder'

Proportional Gain - Larger typically means faster response since the larger the error, the larger the feedback to compensate. An excessively large proportional gain will lead to idle instability.

Integral Gain - Larger implies steady state errors are eliminated quicker. The trade-off is larger overshoot: any negative error integrated during transient response must be integrated away by positive error before we reach steady state.

Derivative Gain - Larger decreases overshoot, but slows down transient response and may lead to instability.

right

PID lockout RPMDOT - I assume that if I am in a accel over the amount specified PID stops, not sure for what purpose?

PID lockout max decel load - Same as above in the opposite direction?

these 2 test are a check which will ensure that idle speed control will not engage if rpmdot or engine load are above these values. SO, if endine speed is changing or if you are decelerating in gear and the engine vacuum is below a 'normal idle' vacuum value, it will not engage idle speed control.

This is how I understand it, anyway.

KeithG

[tk_tech]

thanks keithg

this is what i was looking for, closed loop was new to me. my iac seems to be running in steps not % is this right.

for min duty or max steps, is this the difference between, idle open and idle closed duty.

and for some reason my idle open and idle closed duty seem to be reversed. i just swapped the numbers around.

thanks for the help
sean

[460stang]

Thanks, now I am off to tune. This dang MS extra code does not work well with my personallity, I think I have tweakers disease, I just can't stop. I can hardly get to work without stopping on the side of the road to fiddle with some settings

[Keithg]

thanks keithg

this is what i was looking for, closed loop was new to me. my iac seems to be running in steps not % is this right.

for min duty or max steps, is this the difference between, idle open and idle closed duty.

and for some reason my idle open and idle closed duty seem to be reversed. i just swapped the numbers around.

thanks for the help
sean

I am pretty sure it is % and not steps, but I do not know how the Stepper motors are merged into this code. Never used one. I think that is what is meant by 'steps', but I am not sure. Min Duty is the minimum duty cycle that would yield an idle speed slightly below warm target RPM with a cold intake and no accessories pulling load.

KeithG

[460stang]

I have been playing with idle settings for a couple hours now (not getting very good fuel milage ).

Here is some of my findings.

Prop Gain- This seems to be the most important setting. Numbers between 5-10 are working well for me. Lower nets slow or no change to correct idle speed. Higher nets to much overshoot

Integral gain - .5 seems to work well, more causes oscalations less and it ignores idle errors over 100 RPM

Driv Gain - .5 is all I can have without oscalations

Also noted that it is important to set closed duty right at where it just starts to affect idle speed. For the honda it was 30%. Less would allow it to drop lower duty but without having any affect it would just allow for more time for idle speed errors.

It seems that the function of closed duty and min steps for PID do the same things and are reduntant.