MS3 Stock IAC

[RJSzynal]

I've installed MS3 to my 1991 Soarer V8 (1UZFE) and just have the IAC and fuel pump to transfer control of.
I've attempted to transfer the IAC but as there are 4 wires (excluding 12V) in the IAC and 4 wires from Megasquirt I'm left with 24 different combinations for them to connect in plus I'm unsure whether it's a moving only or always on valve. I could go through every combination when I get time but there's still a chance I don't have the correct setting so I'd pass the correct wiring thinking it's not working.
My research indicates there are two coils with a connection at each end (Hence the MS outputs being named 1A, 1B, 2A and 2B) and that there should be about 50 Ohms between connections on the same coil and nothing between seperate coils but I get 50 Ohms between them all!!
The ECU pinout diagram seems to indicate that the coils are ISC1/ISC3 and ISC2/ISC4.
I read somewhere that it has 125 steps and have been using this setting, is that correct?

Any information about the stock IAC valve would be useful for me and anyone else who ever searches on here for the same information.

Thanks
Robert

 

[bartledoo]

I gave up and cracked the throttle plate because of the shear number of possible combinations being too annoying for me. +1 for the exact wiring combo from anyone using MS3. I still need a valve to make my car cold start exactly like a factory tuned car instead of the low cold idle. Have been thinking about putting in an on/off Bosch valve but would like to utilize the closed loop idle feature of MS3.

 

[gloverman]

I have the wiring for a link ecu which shows the two coils. It took me a few hours years ago to get the wiring working correctly and get the settings right along with some problem solving. Flick me an email to info@thecartunecompany and I will email it over. It should be helpful. Once you identify the coils it will reduce the conbinations to working correct or backwards and not working. Cheers

 

[RJSzynal]

Thanks for the help, I've sent an email. Once I find the correct setup specifically for the MS3 I'll post it up here.

Robert

 

[gloverman]

Did my email come through? If so was it helpful? Cheers

 

[RJSzynal]

Yes! Sorry I haven't posted, I've been working so I haven't had time to experiment. The tables seem useful, one of them appears to indicate that 97 steps is fully open, the colours of the wires are different to what I have though so I'll need to look at the connector itself to see what colours they are on my car. I'll post up if I learn anything.

Cheers
Robert

 

[gloverman]

Sorry dont use the colours as they are for the link but use the picture to locate the pin placement. The settings are the ones I use for a stock 1uz with the throttle stop at the factory setting using a link ECU. Around 97 steps gives me the idle I like. I beleive the stepper has around 125 steps. Good luck. Cheers

 

[bartledoo]

Any definitive wiring scheme for the factory IAC? I am still being lazy and waiting. I plan to put a new A/C compressor in soon and would like the idle up feature.

 

[hrforever]

Would like to raise this thread from the dead as the IACV wiring/working is unusual to say the least. My searching has failed to find a definitive wiring solution even though it appears there are motors running around with the valve working with after market computers. Today I tested the connectors to see what wires were what and found that the two larger centre ones (black/red on mine, 95 SC400) are connected together and the other 4 wires give an ohms reading of 43.5 when connected back to either of the black/red wires. When a reading is taken between the 4 wires the ohms are 85.8.

If the valve uses 2 'coils' like its been suggested elsewhere, then the wires should be separated in some way. Anyone have an answer?

 

[gloverman]

I emailed my wiring for the link ecu to factory stepper last time. It shows how I wire it up so this may be helpful for you. My email is above. I can sent it through to you and you can work out the megasquirt diagram. Cheers

 

[hrforever]

Email with new address sent.