# TB selection with IAC on Megasquirt?



## Sr. Karmann (Feb 5, 2009)

Looking for some suggestions for a decent TB with IAC that will work with Megasquirt 3. I've tried searching/googling here and in the MS forums, but keep coming up with old ass threads...

It's a 2.0l 16vt on MS3X with a Scirocco mani that I do not mind cutting and welding for a proper TB flange.

Running a Passat auto TB right now, but the engine seems as if it wants more air, running NA for break-in.

Thanks in advance :beer:


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## need_a_VR6 (May 19, 1999)

OBD2 throttle bodies have an integrated IAC. The only downside is that they need higher freq to run (200+hz). It should be no problem on an MS3.

However, why not use a simple two wire idle valve?


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## Sr. Karmann (Feb 5, 2009)

need_a_VR6 said:


> OBD2 throttle bodies have an integrated IAC. The only downside is that they need higher freq to run (200+hz). It should be no problem on an MS3.
> 
> However, why not use a simple two wire idle valve?


I've heard those TB's give a hard time due to the PWM and the OE ECU learns with the IAC??? 

I am trying to avoid possible boost leaks, clutter and additional equipment and am not opposed to veering away from VW to utilize a TB with a stepper IAC


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## Prof315 (Jan 5, 2009)

Any non drive by wire GM throttle body has a stepper IAC on it. 92-95 4.3 Vortec (non sequential ) out of an S-10 Blazer should work size wise


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## Sr. Karmann (Feb 5, 2009)

Prof315 said:


> Any non drive by wire GM throttle body has a stepper IAC on it. 92-95 4.3 Vortec (non sequential ) out of an S-10 Blazer should work size wise


Thanks Jeff, I will keep my eyes open in the local yard :thumbup:


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## need_a_VR6 (May 19, 1999)

Sr. Karmann said:


> I've heard those TB's give a hard time due to the PWM and the OE ECU learns with the IAC???


I have a few customers using them open loop and they work well.


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## Sr. Karmann (Feb 5, 2009)

need_a_VR6 said:


> I have a few customers using them open loop and they work well.


Thanks for the information Paul and if I do end up going this route, I may have a few more q's :beer:


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## Prof315 (Jan 5, 2009)

need_a_VR6 said:


> I have a few customers using them open loop and they work well.


Do you have known workable settings Paul? I've got a couplef those TBs laying around and wouldn't mind giving it a try.


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## need_a_VR6 (May 19, 1999)

Here's my start:

Freq 30 (*6) hz
Cold duty 24%
Warm duty 16%

Give that a shot and report back


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## Sr. Karmann (Feb 5, 2009)

need_a_VR6 said:


> Here's my start:
> 
> Freq 30 (*6) hz
> Cold duty 24%
> ...


awesome info, need to see about making this happen :thumbup:


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## Rocco R16V (Oct 7, 2008)

Sr. Karmann said:


> Looking for some suggestions for a decent TB with IAC that will work with Megasquirt 3. I've tried searching/googling here and in the MS forums, but keep coming up with old ass threads...
> 
> It's a 2.0l 16vt on MS3X with a Scirocco mani that I do not mind cutting and welding for a proper TB flange.
> 
> ...


please post results, I'm in the same situation, running 16v w passatTB and want to eliminate boost leaks and clutter from separate IAC valve. 

Thanks :beer:


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## Sr. Karmann (Feb 5, 2009)

need_a_VR6 said:


> I have a few customers using them open loop and they work well.


Getting this wired up soon, I've settled on an OBDII VR TB. I was looking through the settings and I'm unsure of which selection to make in Tunerstudio. PWM Warmup 

I also plan on using this as a guide http://forums.vwvortex.com/showthread.php?4792983


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## need_a_VR6 (May 19, 1999)

Start with pwm warmup, get it adjusting reasonably then try closed loop.


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## Sr. Karmann (Feb 5, 2009)

need_a_VR6 said:


> Start with pwm warmup, get it adjusting reasonably then try closed loop.


Ok, but still confused on wiring. Says I can use FIDLE on the output port, but when you go to closed loop, that selection box goes gray. Did you see the link in my previous post?


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## need_a_VR6 (May 19, 1999)

If you have 3x and no stock idle upgrade you should use 3x's idle pin.

The wiring in g60t's post is right, I worked with him to figure it out and get it working. 

Not sure why it gets greyed in closed loop mode unless its locking you into using a specific output.


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## Sr. Karmann (Feb 5, 2009)

need_a_VR6 said:


> If you have 3x and no stock idle upgrade you should use 3x's idle pin.
> 
> The wiring in g60t's post is right, I worked with him to figure it out and get it working.
> 
> Not sure why it gets greyed in closed loop mode unless its locking you into using a specific output.


Will do, TS lets you choose idle or Fidle and I was mistaken, it is only some closed loop control that grays out the box, not PWM :thumbup:

Thanks Paul :beer:

I will definitely report back with results, still some modifications to be done to the new SRI


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## Sr. Karmann (Feb 5, 2009)

Sr. Karmann said:


> Will do, TS lets you choose idle or Fidle and I was mistaken, it is only some closed loop control that grays out the box, not PWM :thumbup:
> 
> Thanks Paul :beer:
> 
> I will definitely report back with results, still some modifications to be done to the new SRI


 Back from the dead, actually running some wiring now, doing some research to find where to pull 12v from. It would be nice to pull it from the injectors, but dunno if it is constant at startup, IIRC, I remember reading somewhere to hook it to the fuel pump relay.


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## need_a_VR6 (May 19, 1999)

Ignition switched power is fine. It has a cranking duty setting that you can set higher if you get low voltage during cranking.


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## Sr. Karmann (Feb 5, 2009)

need_a_VR6 said:


> Ignition switched power is fine. It has a cranking duty setting that you can set higher if you get low voltage during cranking.


 Good to hear :thumbup: 

I referred back to the bentley and the inj's do in fact come from the same source supplied to the FP relay, so I soldered that sukker in. 

I haven't worked on this car in quite some time, so now I'm trying to track down a good ground, going to find a MS based ground and connect it there, being that I have about 8 of them grounded to the head. For some reason I have 2 separate leads with about 4 wires each, tracking them down now to be sure they are in fact headed directly to the box.


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## Sr. Karmann (Feb 5, 2009)

I just had a :facepalm: moment, thought it was 3 wire, +, - and sig, but :banghead: as I have an extra wire... Sukks I don't have this all printed, back and forth on the PC is rough 

Hooking up the pin 9 idle to the ground now. It also says I need to do a V3 board mod, going to research that a little later :thumbup:


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## Sr. Karmann (Feb 5, 2009)

She runs...

I used the wiring provided in the link and had to reverse the TPS power & ground, other than that, all went well. Going to do some tuning on the IAC tomorrow


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