letitsnow Posted November 24, 2007 Share Posted November 24, 2007 Seeing as these cars don't have an easy way to mount a computer controlled IAC, would it be possible to use the fast acting boost control solenoid as a PWM IAC? Just tap into a vacuum port on one side and put a little filter on the other. Quote Link to comment Share on other sites More sharing options...
mobythevan Posted November 26, 2007 Share Posted November 26, 2007 Is the valve large enough to provide enough air for cold starts? I use an air valve from my old 13B rotary for my cold start valve. It has a diameter of ~3/8", that works well when it is really cold. Quote Link to comment Share on other sites More sharing options...
letitsnow Posted November 26, 2007 Author Share Posted November 26, 2007 I don't know how big it is, I'd assume that it's the same size as a wastegate vacuum line, so ~1/4". It might not be big enough if the car is driven in really cold weather, but mine won't be so it might not be an issue. Quote Link to comment Share on other sites More sharing options...
zcarnut Posted November 26, 2007 Share Posted November 26, 2007 I’ve used the Bosch IAC valve and controller module I got off an early 1980’s BMW. What’s nice about is that it is a “stand alone†system. All the controller does is monitor the engine rpm at idle via the hot side of the ignition coil and uses a PWM amp in the controller module to regulate the air flow through the valve. You can even use a temperature sensor and have a “fast idle†when the engine is cold. I put this on a Z car that I had installed the SDS fuel injection management system on, which completely ignores the idle speed function. Quote Link to comment Share on other sites More sharing options...
Xander Posted November 27, 2007 Share Posted November 27, 2007 wow, I was not aware that this controller exited. This could be the solution for my Z. Do you have any pictures for when I go to the pick'n pull? Quote Link to comment Share on other sites More sharing options...
zcarnut Posted November 28, 2007 Share Posted November 28, 2007 Do you have any pictures for when I go to the pick'n pull? The Bosch idle speed controller and the idle air control valve were used on the 1982-1987 5 series and 3 Series BMW’s (318, 325 and 528). The controller unit (module) is a small green plastic box (about 2" x 3" x 1" thick) that is located in the upper portion of the glove box area. Be sure to cut off the controller’s electrical connector from the wiring harness. This will make interfacing with the controller easier. The air control valve is silver and can be found in the engine compartment near the shock tower. Again, try to get the harness connector. Quote Link to comment Share on other sites More sharing options...
letitsnow Posted November 28, 2007 Author Share Posted November 28, 2007 I want everything to be controlled through the megasquirt though, I could probably just use that valve and have megasquirt control it via pwm then, right? Quote Link to comment Share on other sites More sharing options...
zcarnut Posted November 28, 2007 Share Posted November 28, 2007 I want everything to be controlled through the megasquirt though, I could probably just use that valve and have megasquirt control it via pwm then, right? I agree that using Megasquirt to control the air valve is a better approach. The resistance of the BMW valve is about 10 ohms, so make sure that the PWM amp in the Megasquirt can handle 1.5 amps. Quote Link to comment Share on other sites More sharing options...
letitsnow Posted November 29, 2007 Author Share Posted November 29, 2007 I think it should be able to handle it, the valve is actually controlled by a TIP122 which, from what I've gathered, has a max current of 5A. Quote Link to comment Share on other sites More sharing options...
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