Idle Speed control valve
 

Hey everybody, so I just installed Megasquirt ms3pro into my 92' Miata and I am not quite sure if the idle speed control valve, just below the throttle body, has any use to me now that I am running a turbo setup. I understand that idle is controlled primarily with megasquirt by coolant temp, timing, and the air temperature sensor. I just don't know if the idle speed control valve has a role now that I have megasquirt. Anyone know? :) Also I have the original throttle body from 92' and I understand that if you are running turbo with a stock ecu, then you need to route the iscv to your intercooler piping.

Yes you still want the idle valve. Yes the Ms is controlling it. Yes you need to tune with it. Yes you need to route the hose out of it into you intake piping.

^What he said. Plumb it to the intercooler pipe coming to the throttle body.

ok thanks guys

If I may, I will piggy back on Jgilby's thread, as I have a similar idle question. My car is a '93, with Megasquirt 2 , and FM 2 turbo system, and currently no IACV, just running what can be set up without it. I am also a laptop dunce, so rely on help from a friend who is a tuner. My question: to return to IACV functioning,( as I have a 1999 engine with the valve installed, but no wiring or harness plug), can I try and locate the original 2 wires that the stock '93 had for the earlier ISCV control, and use them with a new harness plug to send the signal to the MSG. from the IACV? I think the MSG.2 for my 1993 harness should have the pins in the correct location, if I can find the wires back in the stock harness, which was trimmed back by the PO. If I understand things, then my tuner buddy can open the MGS. and turn on the IACV function, yes? If that is correct, I can do the wiring, etc. I had previously thought the idle control was only needed in the first minute, or so, till the engine warmed up a little, and would live with having to keep the car running with my foot, but would really like having a more stock-like idle drivability. From the above advice, it seems like that may be the case. Thanks!

However, I see that it is possible to run without it. What would I need to change in megasquirt if I could delete this? Or do I even need to change anything?

its possible to run a track car without it.

Since then its a static idle, that cant compensate for varying loads, what is going to keep the car running when the idle loads increase? headlights on, A/C on etc... more load the car wont idle well or die when you put more load on it.

Yes. Look at the base map for the 99-2000 on DIY’s page for config info.

Thanks, I will check it out.