Bosch 2 pin ICV

[wazzu70]

I have a 2 pin Bosch ICV on my engine from the factory (BMW M42). Do I use just the "on/off" style IAC or "PWM"?

I currently have my settings to PWM, but using the IAC lock tool only 0 and 255 values seemed to work. Any duty percent in between did not seem to move the valve.

I am not sure what other settings under the main idle control setup may impact this and if one of those is wrong.

Can any solenoid be controlled by PWM inputs, or only some like the three pin Bosch units?

Any help appreciated!

[GintsK]

You have to mount diode in parallel and use PWM.

[wazzu70]

Thank you Gints.

I am using EC36 pin 6 to control the solenoid. I thought I read somewhere this pin already had a diode internally, but maybe that is incorrect.

If I do need to add a diode, is the diode used for the flyback on the injectors appropriate? Orientation the same?

I had my PWM frequency at 100Hz, should I start with a lower frequency?

[GintsK]

There are 3 diodes related to this pin. But if it is not special order, you need one more. Called free-wheeling diode. Via this diode valve keeps itself opened.
http://www.vems.hu/files/MembersPage/PeterJensen/iac.jpg
Almost any diode above 1A and above 50V suits. You have pair of such in rescue kit.

In fact you can reuse one of existing diodes inside ECU for this purpose. But it is not the official way.

Gints

[wazzu70]

Thank you very much. I believe this is what I am missing to make things work correctly.

Thanks for the wiring diagram!

[wazzu70]

I installed the diode and everything seems to be working correctly. I am not sure if I really needed the diode or not as I realized my idle valve is closed at 30% duty and open at 80% duty. Anything beyond that and the valve stays shut, or just gets "more open" past the point where it is of any benefit. Is this normal?

In the idle settings I set my IAC close position to 80 which is about 30% duty using the IAC lock tool.

In the PWM Idle Control I set my max and min PWM duty % to be the 30% and 80% that I found to be open and closed using the IAC lock tool.

Does this sound like correct use of the idle control inputs? The help dialog for the PWM Idle Control is empty so I am not exactly sure, also in the idle settings the number is not a duty percent, but the actual number that represents that duty I believe.

Sorry for all the questions, just trying to figure this out.

[GintsK]

Seems correct. Without current valve opens a bit in opposite side. It is like mechanical limp-home mode.
In some places there is still RAW value 0...255 what represent 0...100% duty, yes.

[fphil]

"In the PWM Idle Control I set my max and min PWM duty % to be the 30% and 80% that I found to be open and closed using the IAC lock tool."

Yes this is quite confusing if one reads what is written or not. I guess you speeak of the VT menu option "Starting/Idle / Idle Hardware Settings" which opens for some reason as a widget named "Idle Control".

I understand that the parameters
     "Max PWM Duty Allowed" and "Min PWM Duty Allowed"
are related to the PID control of the valve, and limit the DC % variations commanded by the control. In my case (Weber VAE V6, 2 wires) I put Max=100, Min=0 since I am still open loop PID=(0,0,0).
In this open loop case, I believe one has to deal only with RefDC from the widget
    "Idle air valve reference position"
from the VT menu option 
     "Starting/Idle / Reference curve"   
Are you open loop or not?

[GintsK]

Max80 min20 is smart in any case (open or closed loop) with BOSCH valve. At close to zero PWM valve opens again. At prolonged 100% it overheats and later lock itself.

[wazzu70]

Thanks Gints, that is very helpful

Here are my settings as of now. I will need to configure the PID later when I want the idle control to work in closed loop obviously.

[kullab]

Hi

Thanks a lot for the information.

I have mercedes M117 engine with 2 pin Bosch ICV also. My VEMS ECU harness comes with 3 pin configuration. How about if I would like to use the old ICV , what should I do? 

[gunni]

Just use two wires,

one 12v and one output from the ecu.