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LT1 IAC Setup

PostPosted: Sat Feb 07, 2015 12:10 pm
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!!

Re: LT1 IAC Setup

PostPosted: Sat Feb 07, 2015 2:55 pm
by grom_e30
should be covered in the current manuals. http://www.msextra.com/manuals/

Re: LT1 IAC Setup

PostPosted: Mon Feb 09, 2015 7:12 am
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.

Re: LT1 IAC Setup

PostPosted: Mon Feb 09, 2015 9:13 am
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

Re: LT1 IAC Setup

PostPosted: Tue Feb 10, 2015 6:40 am
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.

Re: LT1 IAC Setup

PostPosted: Tue Feb 10, 2015 6:46 am
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.

LT1 IAC Setup for MS3X/3.57

PostPosted: Wed Sep 14, 2016 7:27 pm
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

Re: LT1 IAC Setup

PostPosted: Thu Sep 29, 2016 2:50 pm
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

Re: LT1 IAC Setup

PostPosted: Sat May 13, 2017 9:01 pm
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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