Last time I took the 240 out (MoTeC ECU, EEC-IV style IAC valve) it was nasty to start up, needed the throttle to keep it going for a good minute or so. It seemed OK after that, but idle was a bit less solid while at the lights than it had been.
After fixing my starter problem 2 days ago, thought I'd got for a drive last night ... and it wouldn't idle at all without the throttle. Tried it for a couple of minutes, just wasn't happening.
Note that I had pulled the IAC to see if it needed a clean on the weekend; it really didn't look like it, was quite clean looking & oddly not oily (which given how oily the rest of the intact tract actually seems a little strange - I guessed though that it's not open that much of the time given I rarely use the car in stop-start traffic). I had no carb cleaner so I just reinstalled it.
Grabbed the wrong PC to connect to the ECU (screen too small & no keyboard backlight), I was looking around and not knowing the software particularly well I couldn't find anything wrong ... no errors relating to the IAC, but I couldn't find where it was reporting duty-cycle on the IAC either. Messed with the valve signal frequency (no effect) ... then flipped the polarity of the valve, and revs went up to 2500rpm. Probably fully open (which vaguely concerns me just a little if that's the most air it can provide an unloaded engine?). Figured that sounded like a bad idea, so switched it back the right way ...
... and voila, it worked. And was fine for the 1.5hr drive.
So my question, if anyone has an idea, is whether I "unstuck" the valve by giving it a full hit of voltage, and it's likely to stay unstuck?
Or is it more likely to be on the way out ... should I start trying to find a new one? [quick Googling I couldn't find one, they were really common when I bought it ~15yrs ago!]