Bosch PWM Idle Valve Polarity

[Bainzy]

I finally got it working! Abandoned the test setup (ie a 12v source from the battery) and tried using it wired up to the IGN 12v feed I'd originally set up.

Started at 50hz and could hear quite a lot of noise so figured I'm onto something, tried the test mode again and got nothing. But after turning the test mode on and off a couple of times, it sprang to life - only when entering pretty high values though. Settled on 99Hz as that reduced the noise to almost silent but still got the valve moving.

For some reason it seems to want a duty of 60+ to do anything, so the effective range of the valve is basically 60-100. At 67 it's shut, at lower it goes slightly open again (like when off) and at 90-100 it's WIDE open.

I never lingered in this area when testing it before as I hadn't seen anyone else use these values, but it definitely works in test mode, and now that I've fit it into the car, 67 definitely seems to get the lowest idle. Lowest idle is still a bit higher than it was before installing the valve but at least I now have some sort of warmup idle speed control!

[Bainzy]

Should also add, polarity definitely doesn't matter, I tested this. You can put the 12v feed to either pin (and the MS3X wire to the other) and it will work both ways.

[FLEURS]

I have been trying to use one of these valves but having real problems. In test mode initially valve will not open until high values are tried and then it will not close even when setting duty to zero. I even bought a second valve but exactly the same issues. Can anyone recomend a 2 (or 3) wire valve to use in PWM that just works?

[jsmcortina]

How are you wiring it and what settings. I've used these valves in three different cars and tested on the bench also.

Do note that the diode from signal to 12V is required to give the valve a good operational range.

James

[FLEURS]

My ECU was supplied by Phil R who tells me the diode is fitted, there are only 2 wires, one to +12V and one to ECU. I have tried all the settings I can think of, idle valve test 0 - 100, please suggest settings.

[Bainzy]

I fixed my operating range with the diode - didn't realise it was needed on the MS3X output, which is what I'm using.

That kicked the range down from 70-90+% to 30-60%, and made it's operation noticeably smoother.

Even when working well, these valves don't close when the duty is zero. At their lowest setting, the valve is open about 1/4". Then when you add duty, it quickly closes, and then begins to open again at the other side of the stepper thingy. That's where you get the proper operating range.

Before I added the diode, from around 65 up to 70% would get the stepper to start to close from it's default 'slightly open' setting, a few percent after that wouldn't let air out either side, then the gap would open on the other side above about 73%. Does this describe your symptoms? This is at 100hz by the way.

[walterclark1]

I am using one. The valve operates between about 70% and 95% (just closed to full open). From about 15% to 0% duty it opens some again - a sort of failsafe.

I hadnt heard of the diode trick. Makes sense though.

[FLEURS]

Thanks very much for the advice offered, I knew about the intial open position but not sure the advice does cover the symptoms I have, I 'll try again with the settings you recommend and get hold of a diode as well.

25/05 - put a diode in the loom near to the valve this morning and transformed the valve behaviour, controlling nicely now. Thanks to everyone who offered advice.

[walterclark1]

I added the flyback diode today. The operational range went to around 30% closed and 80% open, using the TS idle valve output test and engine RPM as the indicator of open and closed. After adjusting the idle control and cranking PW settings accordingly, I found the engine does indeed start up, gets to idle and maintains idle better.

[sober]

can i use this valve like Fidle valve?

[jsmcortina]

can i use this valve like Fidle valve?

Do you mean as an on/off idle valve ? They typically flow way too much air and are not designed to be used like that.

Use them in PWM mode as they are designed.

James

[mightywizard]

Can anyone tell me where to find the 2 pin connector for this ICU?

[CRSTune]

Can anyone tell me where to find the 2 pin connector for this ICU?

It's a standard Bosch EV1 style connector.

GM Style EV1 Rear Insert Connector Kit:
http://www.bmotorsports.com/shop/produc ... cts_id/943

GM Style EV1 Rear Insert Connector Pigtail:
http://www.bmotorsports.com/shop/produc ... cts_id/944