3-wire IAC on 8cylinder engine.

[altz1]

Hey,

I would like to use bmw m50 IAC valve (3wire) but I am short of outputs. The user guide shows that I should use injector outputs, but I have a 8cyl VAG engine so they are all used. I drive ignition from stepper in wasted-spark COP mode, so I have some spare IGBT outputs left. Are they able to controll this valve? And how should I set up it ?

Thank you.

[rob@vems.co.uk]

IGBTs will control it fine, how to set it up depends on the type of tuning software you're using, generally you'll select I259 and the channel you want to use as the primary - the system automatically uses next channel as the secondary.
So if you selected I259 and Ch 6, ch7 would instantly become the second channel.

[peter_jensen]

The new Vemstune actually shows the outputs like dual 6,i7 (i for inverted)

[Denmark]

hmmm,

Is this going to work with a 3wire iac, if one of the outputs are inverted , as it shows in vemstune??.
one not inverted and one inverted.

i would think that as there is one close end and one opening end, and a 12v plus on the middle pin on a 3wire iac, that this is not going to work,

/Skassa

[GintsK]

This is how BMW valve actually works. It is grounded 100% of time on one of two pins. And opening is achieved by "dosing" ground between both pins.

[Denmark]

okay,

I look forward to try it on a subaru iac next week...

Thanks,
Skassa

[altz1]

Thankyou for information. Do you happen to know witch of the 2 pins is for opening and for closing? Middle pin is 12v supply. Primary channel (6) should be connected with open side of the valve and vice versa?

[mattias]

Just invert the function in software if higher IAC dutycycle gives less air (lower idle rpm).