IAC with Ignition output?

[silverliner]

Hi, I am new, and I am working on a Audi V8 getting a V3.6 connected.
Is it possible to use a spare ignition output for driving a high current pulsed IAC (2-wire, spring closed)?
The Bosch Type is 0280 140 538 and it makes 1.8A at 14V,
thanks

[rob@vems.co.uk]

You can use an ignition channel to drive an IAC, you just need to set it as the output channel in the IAC configuration page in VEMS Tune

[silverliner]

Thanks, I will do so

[mattias]

Because the ignition outputs don't have any external flyback control (internal 300-400 Volts, afaik?) you should add an external diode, schottky or other that dampen the flyback voltage from the solenoid.

[GintsK]

Because the ignition outputs don't have any external flyback control (internal 300-400 Volts, afaik?) you should add an external diode, schottky or other that dampen the flyback voltage from the solenoid.

Yes, but it is essential also if INJ output is used. Low voltage flyback cut helps a lot for smooth IAC operating.

[silverliner]

please excuse me, I am not that much into electronics, but I am learning. What kind of diode should I use, Type or partnumber and how do I connect it right to the harness. There is 12V (with 10A fuse) which goes to the (+)pin on IAC an the other (-)pin I would connect to a spare ignition output: for example EC36-pin10,
thanks for helping

[rob@vems.co.uk]

Theres a fairly good example on wikipedia:
http://en.wikipedia.org/wiki/Flyback_diode
As for the diode, you could use a 1N4004 (you'll probably find them in the small bag of components that came with your VEMS), but these are slow so you may find that tuning the IACV is not all that it could be.  In the Webshop they sell the BY399 for flyback use, there are a number of fast diodes out there so others may have different recommendations.

[GintsK]

IMO plain 1N400x is fast enough for 100Hz application. Most common diodes around.