Is there some way of telling the ecu (MS2 V3) that the AC has kicked on so that it knows to idle up some more? I started thinking of wiring the AC signal that goes to the compressor to one of the spares, but that's only an output. I don't think that it works that way....

 

Off hand I don't have an answer to your question. But if you are using closed loop idle, the BAC will automatically open to compensate for the extra load from the compressor.

 

Is it going to be fast enough to catch it before it dies?

 

If set up properly it is. It was no problem for an MSI running MSnSE on a 1st gen I did.

 

Cool, that's good news. I just bypassed the original convertible ECU so that I can have AC again. Too damn hot here in south Georgia without it. For right now, until I can start messing with closed loop idle control, I just set the idle a little higher so it won't die. When I get there though, I hope you're right


How about boost control? I wonder if you can use one of the zeal daughtercard drivers and one of the rat's nest vacuum control valves to control pressure to the wastegate. I saw that DIYAutotune sells the boost control kit, but it's just a resistor and transistor with some mounting hardware. The zeal daughtercard already has extra drivers on it, and I'm pretty sure it'll handle one of those vacuum solenoids that the car came with, so long as I put a diode around it to shunt inductive kick away from the transistor.

 

the transistors that come with the zeal kit are really designed for driving relays and such. They're supposed to be good up to 1A though.

The DIY kit's transistor can handle a lot more current.

Ken

 

Nothing stopping me from making it drive a relay which in turn controls the air operated solenoid

 

no, but relays really don't like PWM signals, which is what the boost control works with. Generally they just don't have the response time, so that at low PWM they just stay open, and at high PWM they just stay closed. You might get a little bit of action in the middle, but the contacts inside the relay will hate you, and would be likely to wear out early. A high-current transistor/mosfet is really what you need for boost control.

 

Understood. I forgot about the fact that it would be opening and closing pretty rapidly.

 

I have an IRFZ44Z built into my prototype area for boost control (last time I used it was just for switching water injection on or off however).

I also have a 2n2222 hanging off IAC1 to drive a fan relay.
"PA0/knock enable/JS11" pin is used for rx-8 mode rear rotor leading coil output.
Fidle is for the idle control with a better transistor built onto the board (TIP122).
I hang boost control off IAC2

JS10 is also used by the 2nd trigger from the standard FC3S cas input.

You can always just use a simple on-off output with a tuned orifice to add 200rpm to idle rpm when the engine is below 1500rpm and the input is high.