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101/ bmw M42 idle valve calibration

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I noticed that my solenoid bosch valve working with opposite direction. (I use LINK G4+ monsoon) This is the reason which I can not work close loop idle and I can't use the idle gain table. I send message to LINK and they answer to change the wire on my idle valve, but it is not effective. there is possibility to be problem with valve and I must change it. What can I do with that ??

I have 2 print screen from my PC_LINK with the set up of my idle valve

Attached Files

With a 2 pin idle solenoid it doesn't matter which way you wire it as the ECU is simply pulse width modulating the output. The Bosch solenoids are a little unique in that you need to se the minimum duty to about 30% which is their 'closed' position. What you'll find is that as you reduce the duty cycle from 30% to 0%, the idle solenoid increases airflow again. It's a bit of a weird setup but try that and see how you get on.

Thanks you very much SIMON. I'm surprised that my idle work. I can not understand how work, but finally it work exactly with the way you write. Thanks you again. I try to change the frequency from 25-150 and I don't see a big different. How you understand that better is 25-50hz ?

All solenoids have a frequency range that they will work at. It's been a while since I've used a Bosch solenoid for IAC so i can't specifically remember. If the solenoid functions correctly at 100-150 Hz then there's no problem setting it that high. At lower frequencies you may find that you can hear the solenoid pulsing which isn't a problem but can sound odd.


Some time ago I had bmw with m43 engine, i checked idle valve and original frequency was 100Hz (bosch motronic m1.7.2.. ).

99% M42 is 100Hz too!

Yes, it is the same valve and work perfect with 150HZ I don't see big different between 80-180 Hz. Also the duty cycle is near 38 to 42

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