Idle control using Stepper Motor (M400)

[mr2andy]

Guys,
I seriously have some issue with idle control using the stepper motor running m400 unit. I need to first understand how Motec control the stepper motor. With proportional gain set at 0.05, when I toggle the "polarity" between 0 and 1, I can see the stepper motor valve opening and closing. This is how I check to see if my wiring setup is correct or not. Now that I know the ECU has no problem controlling the valve, I started to play with the idle control setting to monitor how the valve react and this is where I got lost.

First and foremost, I have the idle control wiring up BUT not plumbing into the system. The engine is still running without idle control and the engine is idling fine. The reason I want to add the idle control is because in order to idle properly in cold start, I have to set the idle to around 1000rpm but that also mean during hot idle the engine is still idling at 1000. I know that once the engine is hot, I can have it idle properly at 800rpm and that's the goal with the idle control module I'm adding.

Now, back to the idle control setting, i understand what PID is. My question is, in the motec software, what does initial position mean? what does normal position means? what about Min and Max output?

Can someone explain how motec control stepper type idle control. Should the initial position be fully closed or fully wide open? and normal position mean? What is consider normal?

Help please.

[Scott@FP]

Hit F1 a lot.

For 6 wire steppers like Mitsu, disconnect the two B+ wires.
Aux 5-8 need to be wired correctly for each stepper type. You have not indicated what stepper this is, or vehicle, there are datasheets available for most of the common ones.

Normal Position doesn't apply to steppers, but normal position for PID would be midpoint of control range, 'normal' operating area for those conditions.

Initial position is where stepper goes to on key-on, before starting. Usually coolant temp as an X axis.

Suggest downloading one of the Mitsubishi base maps from http://www.motec.com.au/downloads/startfiles/ and looking it over to get you in the ballpark. However I totally disagree with these base files PID settings, they make the stepper very hyperactive. Suggest using very small P and D values with no Int until you start getting decent response without being hyperactive. Sometimes things work best without P,I, and D all active, sometimes only one or two work better.

[mr2andy]

Its a 4 wires GM stepper motor in a custom alluminum block.

[Scott@FP]

If you haven't seen it there is a datasheet for the GM stepper on the download page, http://www.motec.com.au/downloads/downloadsappdrawings/

[mr2andy]

Hey Scott,
Thanks for looking into this. If the "Delco Idle Stepper Motor #V15" is what you were referring to, then yes, I have already seen that and that's what help me wiring up my stepper motor. Like I said in my first post, by toggling the polarity in the ECU manager software, I can see the valve fully open or fully close which I then confirm that my wiring is setup properly.

I did use the parameter setting that was suggested on the same document. My issue is, no matter what I do on the "initial position" table, I can't seem to get the idle control valve to do anything. Once I switched the polarity setting and see the valve either go fully open or close, it does not respond to any other setting. No matter what I do in the initial position table, the valve sit there and won't do anything.

I'm very much clueless here and desperately need some help.

Thanks

[Scott@FP]

ECU needs RPM signal (run condition) for many of the functions to work. Is this with engine running?

[mr2andy]

Yes, the engine was running... that's the only way to get the idle control activated.

[mr2andy]

Anyone from Motec willing to pitch in some thoughts? Any help will be appreciated.

Cheers
Andy

[mr2andy]

Can someone explain what "Min output" and "Max output" means when it comes to stepper idle control? also the initial position and normal position table.

Cheers

[AdamW]

I've never used a GM stepper with a hundred series but here's a little bit of info that might help:
Min output; this is the closing rate or speed in steps per second (I think). Try a flat line of -200.
Max output; this is the opening rate. Try +200
Initial position; this is how many steps the motor opens when you turn the key on. Try a value of 20-50.
Normal position; not used for stepper.
All other settings as per the datasheet. Make sure the activate TP is above your normal closed throttle TP.
If it still doesn't work post your map and a log of it starting and idling.