The Bosch idle valve I was referring to is the one suggested in the MS manual - a 1-wire heater type.

Look here near the bottom of the page - just above "Ignition Triggering".

Frank

That goes back to the old days of MS-1. Those did not work then and I would not bother now.
The basic B&G stuff is a PIA to use compared to the beautiful works in the Extra code.

Here are two pics of my ISC adapter.

Help me understand that - you removed the IAC stepper motor, made an adapter to fit the opening, then mounted the Ford valve on the adapter.... is that right?

How is it controlled, and can I control it with the B&G software? Does it work well? I see no air fittings.... how does it provide air?

I think you're looking at the TPS connector upside down (or I am) - or - you're looking at the harness connector. Our wiring identifications are mirror images of each other. When I look at the connector on the IAC motor, the raised center mating land is on top.... pin #1 is then on the left.

Frank

Nice find..... thanks! It sounds like the center taps can be left unpowered and connect the coil ends as usual for MS. I suspect there might be some resolution difference in step size or step count, but it sounds like it might work well enough to suit me.

Frank

I've sent an email to Matt at DIYautotune to ask if it's feasible to use the Mitsu stepper.... also PM'd franklynberry to see if he has any suggestions, since I've seen on the MS forum that he had issues trying to use the OE stepper motor.

Enough heads and we'll get to the bottom of this yet. <img src="/forums/images/graemlins/confused.gif" alt="" /> It does seem from the MS post that there's enough resistance in the coils to keep from burning out the driver with current over-draw.

If I can't find out for sure, I think I'll give the stepper motor a good talking to and tell it that it's really a GM stepper motor and wire it accordingly..... and dare it to complain. <img src="/forums/images/graemlins/lol.gif" alt="" />

Frank

My conversion to the Ford ISC is solely for use with MS. It will run off both the MS1 and MS2 processor but I expect it needs the Extra code at least with the early processor.
This will use the original Fidle output with the larger driver retrofitted. It is controlled with PWM.
Basically any code that will run the ford valve.
The air passengers are internal as are the original ISC.

The TPS info is from the FSM, the +5V power should be the Blue-red wire in your plug.
If you and Gen One think the FSM you have then this probably is also. The sun will be up in a few hours, I will go find a connector and look.
The three wires must all go to the MS connector, the ground can not go the engine or chassis. The harness you are using already has the wires all going to the ecu.

The original stepper should be about 100 ohm across it wired this way. To me step size is not important since this should be able to be setup when running.

I just bought a GM ISC, when it gets here I will see if it will retroft into a Mitsu housing.

That would be interesting if the GM IAC will fit - it sure would make things easier if it will.

I'm not using the OE TPS connector plug for the TPS. I grabbed a few connectors from the yards so I wouldn't have to mess with the OE harness - no telling what the connector I'm using came from. The wire colors are different from OE, so the FSM schematic is relatively useless.

I'm fairly confident that I have the TPS wired correctly - if the MS manual is correct. <img src="/forums/images/graemlins/lol.gif" alt="" />

Frank

Matt at DIYautotune "thinks" the IAC will work if wired only at the ends, ignoring the center taps - but cautions that since he hasn't tried it to make sure, I might have to use a 4-pin IAC. I've wired it that way, so we'll see what happens. I read 58.6 and 58.8 ohms per coil this way, so the driver should be ok since the GM stepper motor coils are 58 ohms/coil.

On to the distributor....... Charlie, I'm looking at powering the distributor's optical sensor from the ignition coil (+) to (+). I guess the ground will need to be a separate wire that runs back to the MS ground collection. Alternately, since I'm using a shielded wire for the Vref signal, could I use the Vref shield as optical sensor ground path? Do you see anything wrong with any of those options?

Frank

That sounds easy enough on the IAC.

The dizzy will not work that way. It gets power from the main relay that controls the MS and then grounds to the MS grounds. The two triggers go to there respective terminals at the MS, or just one if that is how you are signaling. The shield gets grounded at one end only, generally the MS grounds. If they get grounded at each end they become a ground loop and will amplify the pulses within. Not what you want. If you have these wires from a donor harness this is already done for you.
Run a separate power wire to the coil, same source is fine.

Yes, I'm afraid the coil lead B+ source will be noisy.

Here's the way I have the coil wired:

I'm using the OE coil harness portion of the OE main harness that includes the coil (+), coil (-) and the LC filter (to the tach)... my hope is that when the ignition switch is in either the RUN or START position, the coil will be energized. The tach should also work (I think). I connected pin 36 from MS to the coil (-) for triggering the coil. Shouldn't that work?

I'm confused about the suggestion of where to tap the distributor sensor B+. Where on the relay board would I connect the sensor B+? I thought about the fuel pump relay, but I think that's turned off when the engine's not running.

Frank