Idle control
Turbo Mini Forums

I wanted to know what everyone who's planning on using Megasquirt for port injection were planning to use for idle control. Nothing, idle solenoid, or stepper motor?

MS2 has both idle solenoid (PWM or simple on/off) and stepper motor control. (Of course it can also handle nothing ) However, the stepper motor control uses 2 timer outputs while the solenoid control uses none. This means that if the stepper motor control is not used we can use the timer outputs for ignition. This allows wasted spark timing control through hardware and frees up the original ignition output for another PWM output (such as fuel pump control maybe ).

In any case, the code will allow wasted spark even with stepper motor control but in that case there will be fewer spare outputs and timing will be software controlled which may be less accurate (nothing major but will require more careful programming and verification). I just want to have an idea of what people are planning, mention the impact of different choices, and ask Peter what he's planning because that might involve choices during the assembly of the board I'm doing now.

Jean

http://www.jbperf.com/

My personal opinion is that when starting a cold engine the use of ign timing only for idle control is not sufficient.
My engine definitely needs more air at idle so some sort of bypass will be necessary. Whether that is solenoid or stepper I am not sure. I have no DIY experience with stepper motors on the Megasquirt. ECU controlled idle (maybe even closed loop) is not on my radar yet.
This problem may not be as pronounced with less cammy turbo motors I am talking about a 276 equipped car with 1.5:1 rockers. HTH.

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

What is currently in the MS2 code is only fast idle control for warmup and static open loop idle. Some people are working on close loop control but it's not there yet.

If you use nothing, and there are some MS users that do just that, you just need to adjust the idle screw and tweek the fuel and ignition maps around idle. You may need to use the gas pedal to start and warm up but that's it. You could even use a "choke" cable to crack open the throttle. The main problem comes from A/C and other high power accessories that could actually stall the engine if there is no active control. I don't think A/C is a concern here but headlights might be.

Do the SPi and MPi engines use a stepper motor or a solenoid? There are plenty of cars that use solenoids so, if needed, fitting one would not be a problem. And I also think that using nothing is a viable alternative for many people.

The choice doesn't come down to having wasted spark or not but mainly in having more spare outputs for different options. Wasted spark will be there regardless albeit with potentially slightly less accuracy if a stepper motor is used.

Jean

http://www.jbperf.com/

MPIi uses a unipolar six wire motor in a bypass valve package on a five pin plug, as an idle 'air' controller

SPi uses a unipolar six wire motor on a five pin plug, as an idle 'speed' controller.

http://www.turbominis.co.uk/forums/index.php?p=vt&tid=10807

I am using the stepper motor in my 16V Bimmer conv. - it works good although it isn't closed loop - which is a shame...
Ignition is wasted spark EDIS setup...
PWM output is ON/OFF used for my electric water pump at the moment...would loke to have it PWM speed controlled which is not possible when using a stepper with MS code at the moment.

Bimmer Twinky headed and turboed A-Series:
http://www.minifreunde.at/harry/projects.htm

The latest MS2/Extra code can do closed loop idle control with a stepper.

The link to the software is on the MSextra forum.

Current latest version is 2.0.1.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Paul,

have you ever seen a software that allows a stepper + PWM on the FIDLE port to be used parallel?

Bimmer Twinky headed and turboed A-Series:
http://www.minifreunde.at/harry/projects.htm

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Hi,
It would be easy enough to switch it through a resistor to slow it down, then direct when hotter, either relayed via MS or off the fan switch...
Cheers,
Gavin :)

VEMs Authorised Installer / Re-seller. K head kits now available!

WB/EGT gauges. Click here for customers write-up

Visit www.doyouneedabrain.co.uk

My Mini build diary

I am using a 2 wire VDO idle control valve with MSV3 and it works really well
Full closed loop from cold start to hot idle.
At the moment I have a 544 cam with modded metro turbo manifold and full race flywheel (not port injection though!!)
Idle speed is around 1200rpm at ave lambda of 0.9 but it is quite stable.

Edited by matnrach on 17th Jun, 2008.

Lots of factory ecu's use it, and some aftermarket allow closed loop idle control using ignition timing. My DTA S80 does this now

Much faster than control valves....and of course you dont need to fit anything !!

Once the throttle is set properly it can work very well with this as the only control strategy.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

Hi,
I use both, the timing and a MPi stepper
My 1380 just used the timing control.
Cheers,
Gavin :)

VEMs Authorised Installer / Re-seller. K head kits now available!

WB/EGT gauges. Click here for customers write-up

Visit www.doyouneedabrain.co.uk

My Mini build diary

Heres a copy of the MegaSquirt Feature comparison table.
http://www.mad-professor.co.uk/Misc/MegaSq...son%20table.pdf