Idle valve control

[lotusbled]

Wondering guys, I'm having problems getting my IAC to operate on my s60. This is the valve I have installed. Some description refer to it as a stepper but most call it a PWM. It is a Ford Focus 2000 - 2004, two wire plug. Any thoughts would be greatly appreciated. Cheers Ross.

[ignitionautosport]

One pin to 12V, the other to idle control pwm (I forget which pin). That's pretty much is as far as hardware goes, what issues specifically are you having?

[lotusbled]

Hi thanks for the response. So I'm assuming that this indeed is a PWM valve as DTA doesn't work steppers as Alex had informed me. So the the cold start is really rough. I have to keep giving it throttle to keep it running. I cracked the throttle plate a small amount to help, but barely idles off throttle. When it warms up all is good however still needs work. When cold though the RPM does not increase to 2000 as set in the "Idle speed parameters" so the IAC one would suspect is not working. I'm going to check the wiring as I have made this mistake before. Also on another forum some one was mentioning that these IAC's have a diode and if wire backwards they will fail. So this weekend I'll check this out. Any other things you may suggest would be appreciated. Cheers Ross.

[Rob Stevens]

Yeh, test it to ensure that its actually operating, use the test function to operate from the ecu.

[lotusbled]

So I tested it and I'm getting a "click" on and a "click" off. No buzzing. Is this normal? Wiring all good. Going to go over all my settings again, I have probably missed something. Ross

[Alex DTA]

Nope, that's normal.

As per my email, you'll have to find out what PWM values work with that valve.
To simplify things, you could add a diode to the wiring to reduce the flyback voltage from the valve.

[stevieturbo]

IMO for starters, just go open loop and populate the PWM table.

Then you can see what sort of values are required to actually make an rpm change.

[katana]

Simple testing as you've done proves it functions - when under ecu control it opens and closes up to hundreds of times a second so you'll hear a 'buzz' when working. A stepper design will have a minimum of 4 wires forming 2 pairs of coils which are turned on and off in sequence to drive the rotor in one direction - reverse the polarity and the rotation will reverse. Horses for courses as they both achieve the same thing although stepper driver electronics are quite sophisticated so less widely used IMO.