Jump to content
HybridZ
Flexicoker

Where to look for a PWM IAC valve?

Recommended Posts

From what I've read, it looks like a 2-wire PWM valve will be the best for my application. I want to do closed loop idle control with MSII Extra. When I head to the junkyard, what cars should I be looking for to find such a valve? Is there a list anywhere? Any experience as to which valve works the best with MS?

 

Thanks

 

-Eric

Share this post


Link to post
Share on other sites

I like using the 3wire pwm valves from the 90's bmw. I have ran them on a few toyota motors with great success. My ms1 v3.0 1997 e36 328is uses the same valve and it does what its supposed to do. Look into the Glen's garage idle board for the 3 wire valve boards.

Share this post


Link to post
Share on other sites
Is there an advantage to using a 3-wire over a 2-wire? Sadly, my Bosch automotive handbook does not cover IAC valves....

 

The two wire idle control valves use the current through a single winding to open a plunger valve against the force of a spring. The amount of current is set by a pulse width modulator (PWM) amp. When power is removed the valve returns to its closed position.

 

The later three wire idle control valves use a rotary type valve and two windings. The rotary valve is opened or closed by the imbalance of current in the two windings and must be driven accordingly by the control circuit. For example, a 50% duty cycle PWM signal on both windings will produce no valve movement. When power is removed the rotary valve will remain in its present location. In general the three wire valves can handle larger volumes of bypass air

Share this post


Link to post
Share on other sites

I thought Fox body mustangs used an easy PWM IAC valve. I have one that I was going to use but I never bothered with an IAC. It's in my toolbox. They have a nice flat mounting surface to bolt onto anything you come up with.

Regarding stepper IAC's, I didn't think they fed current to both circuits at the same time??... Just one depending on how it needed to be changed...?

Share this post


Link to post
Share on other sites

Yeah, here ya go! This is a PWM style and has a simple two bolt flange. All you need to do is get a piece of 1/2" aluminum plate. Drill two holes and tap them to bolt the IAC to. Drill another two holes for the in and out of the circuit (doesn't matter which is which) and tap them for pipe thread. Screw a pair of pipe thread to hose barb fittings and just hook your vac lines up to the hosebarbs. Fab a little bracket to bolt it to your intake manifold and you're set!

 

http://www.autozone.com/autozone/catalog/parts/partsProduct.jsp?displayName=Idle+Air+Control+Valve&itemId=207-0&navValue=15900207&parentId=59-0&productId=3077&fromString=&itemIdentifier=3077_127091_0_&filterByKeyWord=&categoryNValue=&isSearchByPartNumber=&categoryDisplayName=EngineManagement&store=1731&skuDescription=Duralast/IdleAirControlValve&fromWhere=&searchText=&_requestid=316007

 

I have one of these brand new with gasket and flying loom. I'll make ya a deal! :wink:

 

Mark

Share this post


Link to post
Share on other sites

PWM:

Faster response

Less air flow

Simpler ECU control requirements

No memory of where it is

Always pulling juice when idling

 

Stepper:

Can chase itself around sometimes

More air flow (typically)

More complicated ECU control

Stays where you leave it which can take a second to adjust when you are cranking but doesn't need constant energy to stay where it's at

Share this post


Link to post
Share on other sites

I have one of these brand new with gasket and flying loom. I'll make ya a deal! :wink:

 

I appreciate the offer! However, I am on the junkyard budget at the moment. It sounds like a 3-wire is a better valve, however I think I'm going to try a 2-wire first to avoid getting Glen's IAC board, and if I can't make one work I'll go to a 3-wire. I shouldn't need an unusually large volume of air, its just a stock L28. I'm going to be looking for something with hose barbs so I don't have to machine anything.

 

thanks for all the help!

 

-Eric

Share this post


Link to post
Share on other sites
I appreciate the offer! However, I am on the junkyard budget at the moment. It sounds like a 3-wire is a better valve, however I think I'm going to try a 2-wire first to avoid getting Glen's IAC board, and if I can't make one work I'll go to a 3-wire. I shouldn't need an unusually large volume of air, its just a stock L28. I'm going to be looking for something with hose barbs so I don't have to machine anything.

 

thanks for all the help!

 

-Eric

 

No worries. :-) I personally like the PWM IAC as well. I've had too many stepper motors hunting around for my own taste.

Anyways, if you are in "JY mode", I am sure you can find a SBF in the JY to get one from.

Share this post


Link to post
Share on other sites

I stumbled across this site looking for a solution to the cold idle problems on my custom buggy.  

 

http://www.cardomain.com/ride/3923620/1971-volkswagen-beetle/# )

 

This thred led me to the 90's era Jetta IAC Valve ( http://responsive.carparts.com/details/Volkswagen/Jetta/Replacement/Idle_Control_Valve/1995/REPV313201.html?TID=80000000CP&origin=pla&CP=1&CP_SRC=PPC&003=27372932&010=cpreidcova95volkswagenjetta19931999replacementrepv3132011&gclid=CKvsptDg7LgCFUqk4AodEjIAUQ ).

 

This looks great for my application, but does anyone know if the polarity matters on the 2 wire connection and if it does, which wire would be positive and which ground?

 

Thanks,

 

Adam

Share this post


Link to post
Share on other sites

I stumbled across this site looking for a solution to the cold idle problems on my custom buggy.  

 

http://www.cardomain.com/ride/3923620/1971-volkswagen-beetle/# )

 

This thred led me to the 90's era Jetta IAC Valve ( http://responsive.carparts.com/details/Volkswagen/Jetta/Replacement/Idle_Control_Valve/1995/REPV313201.html?TID=80000000CP&origin=pla&CP=1&CP_SRC=PPC&003=27372932&010=cpreidcova95volkswagenjetta19931999replacementrepv3132011&gclid=CKvsptDg7LgCFUqk4AodEjIAUQ ).

 

This looks great for my application, but does anyone know if the polarity matters on the 2 wire connection and if it does, which wire would be positive and which ground?

 

Thanks,

 

Adam

 

Polarity does not matter on the two-wire idle control valves. The control plunger is attracted to the magnetic field regardless of its polarity.

 

Share this post


Link to post
Share on other sites

I stumbled across this site looking for a solution to the cold idle problems on my custom buggy.  

 

http://www.cardomain.com/ride/3923620/1971-volkswagen-beetle/# )

 

This thred led me to the 90's era Jetta IAC Valve ( http://responsive.carparts.com/details/Volkswagen/Jetta/Replacement/Idle_Control_Valve/1995/REPV313201.html?TID=80000000CP&origin=pla&CP=1&CP_SRC=PPC&003=27372932&010=cpreidcova95volkswagenjetta19931999replacementrepv3132011&gclid=CKvsptDg7LgCFUqk4AodEjIAUQ ).

 

This looks great for my application, but does anyone know if the polarity matters on the 2 wire connection and if it does, which wire would be positive and which ground?

 

Thanks,

 

Adam

 

Thanks for this, this looks great for what I need.

 

FYI one of the top links on fleabay is selling them for $22 with free shipping.

Share this post


Link to post
Share on other sites

Zip tied to the remnants of the AFM bracket.  I need to make a better mount,

but before that I want to get a 16mm hose nipple on the cold air pipe so I can

connect the IAC to it and ditch the small filter I put on the IAC.

 

 

What frequency do you have it set at in the software?

Share this post


Link to post
Share on other sites

My ECU limits my choices to multiples of 80.  I found suggestions

of 300 to 320 HZ.  I tried 160 to 960 and found that 320 seemed

to be the best balance between noise (too much when the HZ was

too low) and response/resolution (40 RPM at temp per 1~2% duty cycle)

 

One addition thing to watch with the Bosch/VW IAC is that the ports

are large.  The in port my is about 17mm and the out port about 25mm,

making hose connections an adventure.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...