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Part substitution
Posted: Sun Sep 16, 2012 6:08 pm
by hardline
My PWM IAC Mosfet failed about a week ago. Looks like it is stuck on, as the IAC gets warm fast and it idled at 4500 RPM. I am currently running with the idle set screw run in all the way for cold idle, but I idle at about 1600 RPM warm. I have a few spare IGBTs laying around and was wondering if I could use an IGBT in place of the MOSFET on that circuit.
Re: Part substitution
Posted: Sun Sep 16, 2012 11:45 pm
by trakkies
The only MOSFETs I'm aware of are the two injector drivers. Can you give more details?
Re: Part substitution
Posted: Mon Sep 17, 2012 10:07 am
by hardline
Re: Part substitution
Posted: Tue Sep 18, 2012 4:50 am
by Matt Cramer
That's a power darlington. I suspect an IGBT could work here as long as it can trigger off a 5 volt input. Some can't.
Re: Part substitution
Posted: Tue Sep 18, 2012 6:55 am
by trakkies
As Matt says a Darlington pair (effectively two transistors in one case.) They are cheap as chips on Ebay. Cheaper than an IGBT.
Was it correctly mounted on a heat-sink? Without one it could overheat and fail. If you're not using the ignition driver (Q16) remove it and mount the TIP 120 there. Otherwise fix it to the case. For either, using a mounting kit which insulates it.