LT1 IAC Setup

For discussion of Phil Tobin's Tuner Studio software (Only about the tuning software itself, not about how to tune or firmware features)

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MysticBowtie
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Posts: 10
Joined: Mon Sep 23, 2013 3:51 pm

LT1 IAC Setup

Post by MysticBowtie »

I can't figure out how to configure my factory IAC valve in Tunerstudio. I have gone to DIYAutotune's website. The instructions they have shows an option box for "Idle Valve Type". My current version of Tunerstudio does not have that option. I have the valve wired to Stepper 1A,1B,2A, and 2B. Does anyone know how to configure it?

Link to my current tune file:
https://www.dropbox.com/s/qp2dqhdcev2se ... e.msq?dl=0

Thanks for any help!!
1994 Camaro
LT1, 383, D1SC Procharger 16 psi
LS1 ignition, 2014 Vette MAF
grom_e30
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Location: UK

Re: LT1 IAC Setup

Post by grom_e30 »

should be covered in the current manuals. http://www.msextra.com/manuals/
1990 bmw 320i daily driver with m20b25 ms3 sequential fuel, 380cc injectors, d585 coil near plug, home made cam sync, launch control, fan control, vss, homebrew egt logging what's next????
Matt Cramer
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Re: LT1 IAC Setup

Post by Matt Cramer »

You're on an earlier firmware where you specify both what IAC valve type and closed loop vs open loop in the same drop down menu.
Matt Cramer -1966 Dodge Dart slant six running on MS3X
MysticBowtie
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Posts: 10
Joined: Mon Sep 23, 2013 3:51 pm

Re: LT1 IAC Setup

Post by MysticBowtie »

Thanks Matt. I had double checked the updates for TunerStudio, but didn't think to look for an upgraded firmware for the MS3-Pro. I'll load the current firmware when I get home and see if that changes things.

I've always had the IAC wired per the manual using the 50 ohm test method, etc and was getting no movement, or ability to test the valve. Hopefully the update solves it, and if it does I should be on the road with the car tonight! My fingers are crossed!

Ben
1994 Camaro
LT1, 383, D1SC Procharger 16 psi
LS1 ignition, 2014 Vette MAF
MysticBowtie
MS/Extra Newbie
Posts: 10
Joined: Mon Sep 23, 2013 3:51 pm

Re: LT1 IAC Setup

Post by MysticBowtie »

Matt,

I updated the firmware yesterday. I still wasn't able to get any movement out of the idle valve. I put a voltage tester on the wires coming directly out of the MS3-Pro, and am not getting any readings. I turned on the idle valve "In/Out Cycle" test while I did it expecting to see some movement. Am I supposed to somehow tell the MS3 that the idle valve is connected to the 4 stepper wires? I checked the MS3 fuses, and the 2 small ones are good.
1994 Camaro
LT1, 383, D1SC Procharger 16 psi
LS1 ignition, 2014 Vette MAF
Matt Cramer
Super MS/Extra'er
Posts: 17499
Joined: Thu Apr 16, 2009 8:08 pm

Re: LT1 IAC Setup

Post by Matt Cramer »

They're the only wires a stepper can be wired to.

Try turning off the IAC and setting Stepper 1 and Stepper 2 to general purpose outputs to test the circuit. See this link for details:

http://www.diyautotune.com/tech_article ... re_testing

If it's broken, email us at websales@diyautotune.com for repair.
Matt Cramer -1966 Dodge Dart slant six running on MS3X
Oscar98
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Location: Geneva, IL

LT1 IAC Setup for MS3X/3.57

Post by Oscar98 »

Does anyone have or know the GM LT1 IAC wiring scheme? (1993 Vette LT1 engine)

Mine has the square connector but I can't determine from the MS3 manual what is "low" and what is "high" as called out by Service Manual (unable to attach image due to image size restriction sorry)

I think I figured out that Blue is circuit #A and Green is circuit #B

The reason that I am doubting myself is that it seems as though the colors should match (i.e. MS3 grn/wht to GM grn/wht and MS3 grn/blk to GM grn/red) but that does not match the MS3 drawing for the IAC wiring diagram

What is Low and what is High on the MegaSquirt DB37 connector?

Thank you


Dave
Oscar98
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Re: LT1 IAC Setup

Post by Oscar98 »

Seems like it is working properly with the wiring schematic posted in the Manual for the GM Four wire (Square connector)

Thanks for your replies.

Dave
firebird_1995
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Re: LT1 IAC Setup

Post by firebird_1995 »

Oscar98 wrote:Seems like it is working properly with the wiring schematic posted in the Manual for the GM Four wire (Square connector)

Thanks for your replies.

Dave
I know this is an old thread, but I just wired up one of these and thought the same thing when comparing the gm manual to the ms3 instructions. I am having issues with the iac not operating properly and if I'm understanding you correctly, the way to wire it is how the gm manual shows?

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