Using the factory idle valve on mexibug efi? MS.

[pete nice]

Ok,
I have had a fair bit of help putting my system together. It finally runs, but idles at about 1400 rpm. I am running MS2 V3 & have done the mods to the board to run a pwm idle valve, but just can't get it to work.
I have tried loads of settings to get the idle valve to work, so am looking for either a settings solution or a physical one.

Is anyone running the standard valve or have they been blanked or replaced with something else.
If I put my thumb over the valve completely the engine will stall.
If I earth the valve it will rev to 2,000 rpm.



Engine is a 2017cc with a T2 turbo running all VW Mexibug efi with Audi TT injectors..
Everything is built mild to push a bus around.

I have heard of people porting the TB, but not sure if that's just for performance.
I really want to get this sorted before I fit it in the bus.

[miniman82]

The air is getting in somehow, so either the idle valve isn't working correctly or the idle stop on the TB isn't set right. You sure the idle valve circuit on the ECU is good?

[pete nice]

It's the way the idle valve works that is the part of the problem.

At its home or static position it is part open, when it's earthed it will open fully.

When I blow through it with my mouth I can detect the change easily.

When the either the live or earth is released the valve will spring shut for a split second before returning to its resting position.

By using a pulse it should be able to trick the valve into closing. If you put a finger of thumb over the idle valve inlet it will instantly stall the engine, so there are no leaks as such.

I just can't work out how to get the Megasquirt to pulse the earth. It may be I have to switch the wires so it pulses the live, it would work in the same way.
I did the mod as per instructions, but have no real way of testing it.

[pete nice]

OK, I was being a muppet & have found an idle screw on the valve!

[Piledriver]

I was about to ask if that was a 2 or 3 wire, but you appear to have got it.
That probably is a minimum flow setting.
(3 wires need to be actively opened AND closed, with no power they can go to a ~centered position and flow some air)

[pete nice]

Does anyone know if the above is a PWM valve or stepper motor?

Part number is: (VDO, 408.202/013/002) VW 048 133 455

I am still struggling to get any dense from it.

[Steve Arndt]

That is a PWM controlled solenoid valve. (2 or 3 wire)

Steppers look totally different. They also have 4 wires (minimum).

[Piledriver]

From the description I got searching vwvortex, it's a 2 wire.
(google site search works great)

It's possible it's a) simply worn out, or the return spring is shot.
or
b) perhaps the stop screw needs adjusted so it stops at OFF, and not either side of it.
(has a rotating valve, orientation sets the flow%)

[pete nice]

I am pretty sure it's working fine as all of the mexibug EFI is in near mint condition, there is a picture above. I didn't need to clean any of it before fitting.

It is a 2 wire & if I put 12v across it it opens & will snap shut when released.
The grub screw on the top of the valve will adjust the idle speed when it's running, so I am sure the valve is ok.

I just need to know how to set the Megasquirt up to recognize it, as either a PWM warmup or an IAC stepper motor.

I spent a couple of hours Googleing it last night but couldn't find an answer.

Edit: I just saw your post Steve. That's a great help, I was on the right track.

[Piledriver]

It's a 2 wire, you set the RPM and duty cycle when closed and when fully open in the setup page.
If you have the TIP120 installed, you can drive it directly.

If you are using glenders mods,(suggested) you will have an initial duty cycle table to set up so it know what DC to go to initially at a given RPM, and will lock on the RPM in closed loop.

A LOT of people use that same valve.

From most of your posts it sounds like it's either it's not closing enough or overshooting the closed position.
It's likely that screw sets the closed position.

[pete nice]

What I did was to get the engine running & warmed up with a fast idle, then brought the idle speed down with the stop on the valve.

It doesn't idle very smooth & hovers around 1100 rpm.

I have a TIP122 installed & think it is wired correctly.

If I have a PWM gauge on the cluster (I have a paid version) it shows that it is doing something.

I coppied some figures from this thread to see if it would have any joy: http://forums.corral.net/forums/megasqu ... setup.html

But still can't get anything. I am sure I am missing something simple but important!

[MarioVelotta]

Do me a favor and draw a simple diagram of how you have it wired up.

Also do you have access to a Jimstim or Megastim? This way you can test without having to run the engine.

What frequency do you have in your settings? Per my email if you could send over your MSQ that would help.

[Piledriver]

Bosch runs them at 100Hz.
Play with your idle ve.

[pete nice]

I will mail you my file Mario.

100hz is a very useful bit of info, I hadn't found that anywhere.

Here is my engine, I am running it out of the car.



It's pretty much stock mexibug EFi apart from Audi TT injectors & the T2 turbo.

I have it wired with 12v to the valve & the return to the fiddle output on the relay board. (I did try it reversed, but no different).
When I go back to the workshop on Monday, I will open up the MS board & take a picture of the TIP122 & the wiring.

[yvre]

Reviving an old thread.

Pete,
I was wondering if you'd had any success with your idle valve.
I want to use one with my MS1 and I'm looking for all the info I can.

Thanks