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Old 12-13-2012, 07:58 PM   #1
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Default GM IAT sensor problem

I searched for this using google, using the site search with relevancy selected and on mazda-speed.com with no luck so I apologize if this has been answered. This is probably MSM specific because we have stock IAT sensors so I will probably need someone with knowledge of the MSM specifically.

I installed my reverant built MS2 tuning seemed to be going well until I took a log to solve a problem with my vtcs solenoid. While I was looking at the log I realized my IAT sensor was reading a static 70 degrees which I assume is because it is not actually reading anything. I have a GM IAT sensor that is tapped into the coldside intercooler piping right after the intercooler. I wired it into the two wires of the stock IAT sensor like so:







I have the orange wire from the GM IAT wired to the purple wire with the yellow stripe and the black wire from the GM IAT wired to the black wire with the red stripe. Is this correct? I do not want to start chasing wiring connections if it is hooked up wrong in the first place.
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Old 12-13-2012, 08:39 PM   #2
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Any chance you have access to a hair dryer or a heat gun? Hit it with that and check the MS maybe? Is the range set correctly in the software?

Something definitely sounds off, but I think Rev may be your best bet for a response as he built it, so should know how it is supposed to be wired and configured. I'd wait till he gets back to you before changing anything.

Hope that helps.
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Old 12-13-2012, 08:50 PM   #3
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I didn't setup the parameters for the sensor because I assumed they were setup by rev. He knew which sensor I was going to run. Can someone pm me his email. I accidentaly deleted his email to me and his address doesnt seem to be saved. I know he gets back to emails much faster then private messages.
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Old 12-14-2012, 03:08 AM   #4
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I can't tell by the pics, but the IAT on the MSM should be connected to the IAT that was originally on the throttle body elbow.
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Old 12-14-2012, 10:17 AM   #5
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I wired it to the original sensor on the throttle body and not the one that went into the intake box. I just want to make sure I did not cross the wires themselves because, to be honest, I guessed which wires were correct by trying to figure out which one was the groun wire (black with red stripe was my guess by looking at the other wiring in the bay). If this seems to be wired correctly I will have to look at my connections where I extended the wires off of the pigtail for the sensor.
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Old 12-14-2012, 11:02 AM   #6
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Black w/red stripe is hot at all times and not a ground.

Download this wiring diagram:
http://www.boostedmiata.com/pdfs/MSM_wiring%20all.pdf
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Old 12-14-2012, 11:13 AM   #7
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GD. I read this Mazdaspeed Miata Megasquirt Journal: First Start
and I figured each of these wires corresponded to the GM IAT wires. That is what I get for guessing. Is the black wire from the GM IAT even a ground wire? I assumed it was because it was black and black wires are always grounds.
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Old 12-14-2012, 11:28 AM   #8
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Maybe I'm wrong. Diagram is confusing to me. Two IAT's from the factory? Damn MSM...
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Old 12-15-2012, 02:21 AM   #9
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purple/yellow -> black
black/red -> red
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Old 12-15-2012, 10:11 AM   #10
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Temp sensors are not polarity sensitive, wire them either way around, makes zero difference.
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Old 12-15-2012, 02:33 PM   #11
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That's what I was going to say, it didn't matter for my '93 install obviously a different beast but the same sensor.

Do yourself a favor and buy the $12 harbor freight multimeter for future issues though.
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Old 12-17-2012, 01:10 AM   #12
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the parameters should be preloaded into tunerstudio you just need to tell tunerstudio that you are using the gm iat sensor
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