Second PWM output on MS2 v3.0

danish · Post by **danish** » Wed Nov 25, 2015 12:47 pm

Hello!

I have an MS2 with v3.0 board. I'm already using FIDLE to drive a Ford (EEC-IV / Sierra) idle control valve using PWM.

I need a second PWM output to drive a bypass valve. Can I use one of the IAC outputs?

Thanks!

dontz125 · Post by **dontz125** » Wed Nov 25, 2015 1:25 pm

The MS2 has 2 PWM functions, FIdle and boost control, with no "generic PWM" option. If you aren't using boost control, you can try using the open loop boost control function, which doesn't actually use the MAP signal for anything

danish · Post by **danish** » Wed Nov 25, 2015 4:36 pm

Fantastic, thanks. I want to operate the by-pass valve on a supercharger, and I've now understand a bit more about the settings in Boost/Advanced window of Tuner Studio.

simenon · Post by **simenon** » Mon Jan 04, 2016 7:20 am

Is there any progress? I have similar setup, supercharger from Mercedes with its original electronic bypass valve. It should be PWM controlled but I found out that is motor rated for 12 A what is much more what MS2 can handle.
So I decide to use it only as digital valve (open/close) controlled via relay. I just started few days ago so it still needs a lot of tuning. At the moment I found that is MAP input not enough I will have to add also TPS signal. It is not problem when I have to close valve to create boost, problem is when are ITBs close. In this case boost does not disappear fast enough, so my idea is to add also TPS function. MAP will take care to close valve (around 90 kPa) and TPS to open. Not decide yet which way will work best but will start just with fixed value of TPS (if TPS drops below 20%) but I think that will get much better result if I would take in equation TPSdot instead only TPS.
Here is also one interesting reading (http://www.autospeed.com/cms/article.ht ... lve&A=2181, http://www.autospeed.com/cms/A_2188/article.html ) but with SC wouldn’t work since this controller does not open valve at idling. Maybe is that OK for turbo setup where is almost no boost at low revs?

How it works by you, do you have different setup? What kind of vale are you using?

danish · Post by **danish** » Mon Jan 04, 2016 11:43 am

I have made some progress. I've setup "boost control" in Tuner Studio using IAC1. I also set a "boost control duty table" so that the s/c is bypassed when RPM is 1000 or lower, and TPS is < 20%.

I'm using the bypass valve from a Mercedes C180K. With a steady DC voltage of 2.9v at atmospheric pressure, the valve fully closes and around 2 amps are drawn.

The next step is to build a driver circuit. I looked at this one on DIY Autotune: http://www.diyautotune.com/catalog/mega ... p-160.html as a starting point.

I still have a couple of issues:
- the PWM ratio to achieve a given angle of rotation of the valve is different when opening to closing, probably due to the spring mechanism. There are carbon tracks in the valve, so it's possible to know exactly what position the valve is in, but I don't see any way to do this in Tuner Studio. My best option in the short term is to make a stand-alone valve controller using a PIC.

- I'd like an option for the MS over-boost protection to open the butterfly

Here is the valve powered from a lab PSU:

Paul_VR6 · Post by **Paul_VR6** » Mon Jan 04, 2016 7:21 pm

There is a circuit that was posted to do true servo control that may work, search "trothel idle valve"

danish · Post by **danish** » Tue Jan 12, 2016 3:22 pm

Thanks Paul, I'll take a look.

simenon · Post by **simenon** » Sun Jan 24, 2016 1:57 am

0 280 250 230 - b.jpg

I use same bypass valve (Bosh A 280 250 230) but didn’t go so much in details as you. I just mount it on SC and control it via MS as on/off valve. Valve is normally open (spring operated) it has 6 pins but I use only power supply (other 4 are resistance for throttle position). To close it I use TPS and MAP signals. TPS close valve when is TPS signal higher as 15% - this corresponds approximately to 1800 - 2000 rpm and works fine, there is no surge when valve close. Bypass is closed also when is MAP reading 110 kPa or more. Operator of both conditions is OR.
Since I don’t use PWM modulation is current much higher so I have relay between bypass valve and MS

Before I used membrane and piston operated valves and I had two issues - not enough vacuum to close bypass valve (I have ITBs) and valve usually didn’t open fast enough to release boost when was throttles suddenly closed. I made only few runs with electronic bypass valve and it works good. Would like to test it even more but we got cold winter so project is on hold now.

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