Questions about PWM Idle circuit

Jon k · Post by **Jon k** » Fri Jul 14, 2006 6:53 pm

I built the PWM idle circuit that will HOPEFULLY work with my BMW Bosch 3 wire idle valve. I have a couple questions:

1) When we remove D8 Diode, do we jumper it?

2) The directions say to place a 1N4001 across the valve or copy 1N4001 circuit from 2.2 - can I just replace the D8 Diode with a 1N4001 or will that not work? Do I need to put the 1N4001 across the valve - I hear people weren't using it and the valves were functioning.

3) Is there anyway to test if the circuit is working on a Stim without having a valve in hand?

MS-1 V3 029Q2

slow_hemi6 · Post by **slow_hemi6** » Fri Jul 14, 2006 9:29 pm

When a soleniod valve closes it generates a voltage spike.The diode is there to direct the spike back to be dealt with by the power supply components.If you leave it out, processor resets could become your next problem post.

Jon k · Post by **Jon k** » Fri Jul 14, 2006 9:35 pm

slow_hemi6 wrote:When a soleniod valve closes it generates a voltage spike.The diode is there to direct the spike back to be dealt with by the power supply components.If you leave it out, processor resets could become your next problem post.

Ok but I cannot place the 1N4001 where D8 used to be?

Can I test the circuit with the stim somehow?

slow_hemi6 · Post by **slow_hemi6** » Fri Jul 14, 2006 10:13 pm

NO you can not put the 1n4001 in D8's spot.If you look at the schematic for ver3 [Output Other) you will see that the zener goes from the switched to ground side of the valve to ground.With the 1n4001 ( i would use a 1n4004 also) it goes from the switched to ground side of the valve to the 12v side of the valve or any 12v really.Remember this diode is in reverse polarity and the band goes towards 12v.The point of this is that if the back voltage on the pwm wire goes above the voltage on the supply pin it is sent there.

captain16vgti · Post by **captain16vgti** » Fri Jul 14, 2006 10:29 pm

Jon if you get your 3 wire setup working please let us know. I gave up on trying to get mine working cause I couldn't get a straight answer from anyone regarding these issues. Good luck man.

-Chris

superchargingmachine · Sat Jul 15, 2006 6:55 am

I totally agree with slow_hemi6. You need to remove the D8
(22V 1W) and fit the 1N4001 with the band end going to 12V and the non band end going to IDL. IDL will also go to the grounded side of your valve. The diode(non-band end), the ZTX and the valve ground wire will all connect together at that point in the ciruit.

It may be a little confusing because the V3 Schematic does not show 12V at all in the circuit that contains D8. That is why people are suggesting you look at the V2.2 circuit.

Jon k · Post by **Jon k** » Sat Jul 15, 2006 7:58 am

superchargingmachine wrote:I totally agree with slow_hemi6. You need to remove the D8
(22V 1W) and fit the 1N4001 with the band end going to 12V and the non band end going to IDL. IDL will also go to the grounded side of your valve. The diode(non-band end), the ZTX and the valve ground wire will all connect together at that point in the ciruit.

It may be a little confusing because the V3 Schematic does not show 12V at all in the circuit that contains D8. That is why people are suggesting you look at the V2.2 circuit.

Ok so as long as I have removed D8, removed Q4 and Q20, added the TIP122, and add the 1N4001 with banded side to +12v, but what is IDL? Also, I removed the ZTX for a TIP122. So as long as I do this, I should be fine? And should I stick with a 1N4001 or a 1N4004

superchargingmachine · Sat Jul 15, 2006 8:10 am

IDL is the actual output to the valve. When the output from the ECU(IDL-1) is off IDL will give an open circuit, when the output from the ECU is on IDL will complete the circuit. The ECU gives 0VDC to IDL-1 when the circuit is off and 5VDC to IDL-1 when the circuit is on.

In my 2 wire install one wire gets 12VDC the other is connected to IDL.

I am using a TIP122, I believe you could also use a ZTX650(?) In our circuit these do the same thing at a 2N2222 only faster and can handle more power. The 2N2222 can handle like 0.8A and the TIP122 can handle 5A.

Jon k · Post by **Jon k** » Sat Jul 15, 2006 9:39 am

Ok sweet - so now I have to hook the closed wire to ground and the open wire to the output of the MS ECU?

superchargingmachine · Sat Jul 15, 2006 10:06 am

I don't use the 3-wire valve but the diagram on MSnS-e site shows the modulated line from the ECU(IDL) going to one pin, 12V going to the next and the third going to ground through a 30-40 ohm resitor. I'm not at all sure how you determine what wire is what?

Good luck, the tough part is figuring out settings that work:-( That is where I am at. Read carefully how each value in MT2.25 works to get the settings right. F1 gets you to the help screens and thats where the best descriptions of the variables are located.

Jon k · Post by **Jon k** » Sat Jul 15, 2006 11:13 am

Were you able to somehow test that the output from the TIP122 or what not was even working? I want to make sure its working somehow before I go and tear into the car.

superchargingmachine · Sat Jul 15, 2006 12:16 pm

I don't think you can test the output without an osciloscope(sp?). As far as the settings go you need to tune the the setting to your application on your car.

Jon k · Post by **Jon k** » Sat Jul 15, 2006 12:28 pm

superchargingmachine wrote:I don't think you can test the output without an osciloscope(sp?). As far as the settings go you need to tune the the setting to your application on your car.

Yeah I was just going to see if the outputs some how varied so I don't tear my car apart to try a non-working circuit

superchargingmachine · Sat Jul 15, 2006 12:34 pm

You could just wire the valve in and try it with some hose barbs and fuel line. Sort of a temporary setup if your worried about it.

Jon k · Post by **Jon k** » Sat Jul 15, 2006 12:35 pm

superchargingmachine wrote:You could just wire the valve in and try it with some hose barbs and fuel line. Sort of a temporary setup if your worried about it.

Well my idle valve is on the underside of my intake manifold... here is how it's accessed:

See why I am reluctant?

superchargingmachine · Sat Jul 15, 2006 12:57 pm

I see......

When I got mine out of the JY I hooked it to my beater 89 Chevy pickup's crankcase vent tube at the TB for a source of vacuum and put 12V or 0V to the valve to make it go wide open or fully closed. Could you try something creative like that to be sure the valve works? If the valve is good then you would just be working on MS related stuff out from under the intake.

Gotta run good luck!

Jon k · Post by **Jon k** » Sat Jul 15, 2006 1:02 pm

superchargingmachine wrote:I see......

When I got mine out of the JY I hooked it to my beater 89 Chevy pickup's crankcase vent tube at the TB for a source of vacuum and put 12V or 0V to the valve to make it go wide open or fully closed. Could you try something creative like that to be sure the valve works? If the valve is good then you would just be working on MS related stuff out from under the intake.

Gotta run good luck!

Yeah I know the valve works my car runs with it now on the stock ECU - I want to see if the actual circuit on the MS is working

keithmac · Post by **keithmac** » Sat Jul 15, 2006 4:34 pm

Only real way to test it is to jump in at the deep end..

Jon k · Post by **Jon k** » Sat Jul 15, 2006 8:53 pm

keithmac wrote:Only real way to test it is to jump in at the deep end..

I am thinking that is the case - I had the car running spark and fuel, I am just waitin gfor my KnockSenseMS and then I'll wire the PWM control in while I am at it. I will keep everyone updated.

In case I cannot get it to work, is there a idle valve with simple hose connectors that is KNOWN WORKING with MS? I looked at some ford valves but they have like oddly shaped inlet and outlets. My manifold has a ~5/8" hose inlet that the valve is hooked to via abour 3" of hose.

scirturbo · Post by **scirturbo** » Sun Jul 16, 2006 2:46 am

What you can try is replacing the valve for a 12V/5W light bulb (or led). The light intensity should give you some indication.

SFC

----- Original Message -----
From: Jon k (jkensy@comcast.net)
To: megasquirt-mss@msefi.com (megasquirt-mss@msefi.com)
Sent: Sunday, July 16, 2006 5:53 AM
Subject: Questions about PWM Idle circuit

keithmac wrote: Only real way to test it is to jump in at the deep end..

I am thinking that is the case - I had the car running spark and fuel, I am just waitin gfor my KnockSenseMS and then I'll wire the PWM control in while I am at it. I will keep everyone updated.

In case I cannot get it to work, is there a idle valve with simple hose connectors that is KNOWN WORKING with MS? I looked at some ford valves but they have like oddly shaped inlet and outlets. My manifold has a ~5/8" hose inlet that the valve is hooked to via abour 3" of hose.

This post is at: http://www.msefi.com/viewtopic.php?p=130788#130788

Posted by email.