Anyone using 3-wire Idle valves?

[Jon K]

I have here on my desk a bosch 3 wire idle valve. I was thinking of trying it out but I just realized that the DTA wiring diagram says Bosch 3 pin idle fast side. Does it mean "idle fast" aka "open side"? Little confused on that one.

[VR6Turbo]

It basically means the valve opens and closes electronically, instead of opening one way and then being pulled shut by spring pressure.

I have no idea what advantages this kind of valve offer over a 2 pin valve, but BMW seem to like them.

So anyway, "idle fast" would be opening the valve one way (opening one would guess) and "idle slow" would be closing it again.

[Jon K]

Yeah I was more confused about the terminology "Idle Valve Fast Side"

I guess I'll give it a shot!

[VR6Turbo]

Yeah, Allan's terminology takes some getting used to!

[Simon P.]

Hey Jon,
I'm currently using a Bosch 3 wire, part # 13411733090. It's the stock OE ICV that came with my S54. My idle isn't perfect (I get a bit of "hunting" when dead cold, goes away quicly though...) I'm still tweaking it but its working very well for me.

[Jon K]

Simon that is very similar to the valve I want to use. How do y ou have it wired?

[Simon P.]

Center pin is constant 12v on most Bosch 3 pin ICV's, one of the 2 outside pins to idle output on DTA (pin 8 on S100 in my case) and last pin to Aux 3 (pin 33 on S100). Then to activate the 3 pin ICV, in Idle Speed Parameters, check the box marked "Link with Aux 3 for Bosch 3 pin valve". Now the fun part is determining which outside pin is the "fast side". Because each model ICV is different you have to bench test this. Set up the valve and power the center pin with 12V. Then ground one of the 2 outside pins. This will either close or open the valve. The pin that opens the valve is most likely the "fast side" pin which goes to Aux 3. You can test the valve by blowing through it to confirm open/closed.
Interresting tidbit I found; many people think that the 3 pin ICV's have no return spring because the valve movement/position depends on which side is pulling to ground but that's not quite true. Although the spring is very soft in these, there's still a default position at which the valve returns when not powered. Case in point; if my engine is running and warmed-up and I unplug the valve the engine always defaults to 1400ish RPM. Everytime. And I've tried it quite a bit while playing with idle parameters. Then I if I reconnect, my idle drops back down to the programmed 1150.
Hope this helps

[Jon K]

Ok thanks Simon thats more of what I was looking for - which is the "fast side".

I got my ICV working on bench and ID'd the pin for opening. I think I might plumb this this weekend!

My valve actually has no spring. Inside is a rotational slider jobby. If I open the valve and unpower, he stays. if I close and unpower, he stays.

[Simon P.]

Yeah, mines also a rotational style valve but for some reason it seems to default to a fixed setting...Maybe vacuum is pulling it there??? Anyways, once set-up try unplugging it while the engine is warm and idling just for kicks. See if it defaults. Just curious
Let me know how it goes, maybe we can share settings. Like I said previously, I have mine set-up pretty nice but there's always room for improvement.

[Jon K]

Thanks Simon I will let you know how I make out. Kind of a drag to have to run another wire (wasn't planning on running a 3-wire) but I think it should work out.