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DISCUSSION => Engine management => Topic started by: e30driver on October 31, 2022, 01:18:05 AM

Title: How to remove the screw on the ICV?
Post by: e30driver on October 31, 2022, 01:18:05 AM

Hello everybody!
I am writing to you to ask if anyone knows how to remove the stop screw on the ICV.
I have read a super beautiful post here: http://www.m42club.com/forum/index.php?topic=19719.15 from the user: bmwman91. But... I haven't understood how to remove that screw.
Thanks in advance!

Title: Re: How to remove the screw on the ICV?
Post by: bmwman91 on October 31, 2022, 08:21:52 PM

It is a hassle. You need to chip out the epoxy filler they put in there. IMO, there is NO good that can come from messing with it if you are planning to actually operate the engine with the ICV. The set screw will probably not stay in place once the epoxy is out, and it will be subject to a lot of vibration & impact as the valve door whacks against it. If you are having idle issues, playing with the stop screw in the ICV will only make things worse.

Title: Re: How to remove the screw on the ICV?
Post by: e30driver on November 01, 2022, 02:00:18 AM

Thanks for the answear!
My problem is that I would like to adjust the stop position. In fact, when not triggered, the ICV let a bit of air to flow inside....
Do I need to twist the screw with a specific tool?

BTW: I am trying to install an ICV on a bmw e30 year 1983 whose Additional Air Slide Valve is dead. I'd control it via a potentiometer installed inside the car...

Title: Re: How to remove the screw on the ICV?
Post by: bmwman91 on November 02, 2022, 11:35:47 PM

Ah, ok so not an OEM application. Yes, the stop is set so that it is partially open to let in enough air to let the M42 engine idle if the ECU or wiring have a problem.

You do not need to mess with the set screw if you will be manually controlling it. As you apply voltage, the door will first close, and then open again as the door continues to rotate with increasing voltage. In my ICV's case, it seems to be fully closed with 3-4V applied. The hard part is that it is not intended to be controlled by DC voltage, and I do not think that the positioning is very repeatable that way. It is driven by a 100Hz 12V square wave, and the duty cycle determines its position.

Anyway, you can certainly give it a try with a manual control. The ICV coil resistance is only around 8 Ohms, so you will need a pretty high power potentiometer.

If you are good with electronics, you can make a little circuit to control a transistor with a potentiometer. As long as you can supply up to 2A it could work.

A better solution would be to use the potentiometer to control a 555 timer's duty cycle with it running at ~100Hz (exact frequency is not all that important, it can probably be higher) and then the 555 output driving the transistor. Do note that the ICV will produce some inductive kickback when running it in a pulsed manner, so you want a transistor that can handle at least 50V, better 100V, on its collector.