M400 Idle Control

[nick_968]

I am trying to get the idle control (V3 software) to work a bit better on my M400.

The problem I m having is it takes too long to catch it when the revs are dropping.

When I log the duty of the valve (3 wire) I can see that as the idle control kicks in below 1600 it starts to wind the valve closed - i.e. the opposite way I want it to do as it sees the engine at say 1500 rpm which is higher than the Aim RPM so by the time it reaches the target RPM the valve is in the wrong place then it has to open to get back to the right RPM.

What I really want it to do is not go in the opposite direction when it is on its way down to idle speed so it catches it quicker.

So for example if the normal position is 21, the valve is dropping to around 15/ 16 on its way down when idle control kicks in and then coming up to about 23 before finally settling down around 21 again. Increasing P and/ or D does not seem to help much.

Currently at:

P 0.1
I 0.05
D 0.1

I have tried dropping the activate RPM to 1300 to try and limit how far it goes in the wrong direction but this has not made much difference.

Is there a way of clamping the lower value so it does not drop below the normal position as the revs drop?

[stevesingo]

You can do a few things to help.

Adjust-Functions-Idle Control-

Initial position.

This sets the position of the valve when idle control is not active

You can set an initial position for the valve. Log what your normal position duty cycle is at warm idle. Create a 2d table using rpm as the x axis, and set values at 4, 8, 10, 12, 1600 rpm. Use the normal idle position duty in the 800 & 1000rpm. At the 1600 set to 20 (i.e. closed) and at 1200 set the value to the mid-point between 1000 and 1600rpm.

Normal Position.

This sets the position of the valve when idle control is activated. Set this to the normal idle position duty value. This allows the the ECU to anticipate where the valve will be.

[Scott@FP]

Try using no or very small P values, some systems like it. Set up a normal pos table that is correct for temp (ET vs RPM). Make sure the setup/activate RPM, Gnd Speed, TP values are correct for the situation and you aren't fighting a system that isn't turned on when it should be. Ign trim vs idle aim error, if its high pull timing, low add. Set your base timing in the cells around idle to a lower value like 5 degrees to help stabilize idle vs. high timing. Fuel needs to be correct in cells around your idle speed.

WOT is easy, THIS is the stuff that takes time.

[stevieturbo]

Set base warm idle with the valve at a low position, say 10, 15, whatever ( which may of course require adjustment of the blade position )

That way it should be almost impossible, or at least very difficult for idle control to pull rpm lower than your desired idle position
Idle control will largely be used to increase idle speed when cold etc.

[nick_968]

I have tried small P values down to 0.05 but it does not work as well. That being said maybe with a 2D normal position table that may work better once it indexes off RPM as well as temp.

Re a 2D Initial position table I don't have any option for a 2nd axis in the Version 3 software for initial position only for the normal position or feed forward values.

Interestingly you can also add a 2nd axis in the Aim RPM table for RPM but not sure how this would work in practice...?

I also get the logic of setting the warm idle with the control valve at min duty cycle but I was just trying to follow the Motec webinar guidance of setting the warm idle just below the target RPM but if I cannot get it to work by playing with the other tables then I will have to revert to this. It would be nice to get the PID to do its job properly though.