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Old 06-30-2015, 08:38 AM   #1
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Default Incorrect IATs

I am having intermittent issues with artificially high IAT readings. My temps are usually 10-15 above ambient at cruise. I have the sensor placed 1 foot from my Throttle body and my meth nozzle is 1 foot before the sensor.

This morning was 65f outside and the car read 120f when I started it. It only varied from 105 (after lots of meth) to 125. Obviously this causes me to run leaner than I should.

Ideas? I plan on going back out to the car on my lunch break and checking the plug and wiring.

Details:
Rev built ms3 basic
gt2560r, intercooler
meth installed 1ft before sensor
Gm iat sensor
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Old 06-30-2015, 09:30 AM   #2
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Engine to chassis grounds clean/tight/present? Engine to harness, MS to harness/chassis (a difference in grounding locations can make IAT off just like o2 or any remote electrical sensor). Ohm test the sensor against known values at ambient.


Edit:
Wait! If this is an open element IAT (they make open and closed versions) then the meth is probably causing corrosion. Switch to the slower responding but more robust enclosed type. Or just plan to replace it periodically. They aren't expensive.
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Old 06-30-2015, 09:32 AM   #3
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recalibrate to GM AIT, to ensue it's correct.
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Old 06-30-2015, 09:58 AM   #4
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I will be checking grounds and calibrations tonight. Does anyone have the Gm part # for open and closed element sensors handy ? I may grab a new one from napa tonight
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Old 06-30-2015, 11:15 AM   #5
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check your calibration first.
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Old 06-30-2015, 01:14 PM   #6
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Just recalibrated. As expected no change. Grounds look fine. I think I just fouled the sensor. I'll report back after I replace it.
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Old 06-30-2015, 05:27 PM   #7
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I don't know where to find the number/applications where it was used. I just know there was one. The downside was slightly slower response to temp changes than the open version. DIY Autotune might know if you call them.
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Old 06-30-2015, 05:29 PM   #8
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Ding! GM Closed Element CLT / IAT Sensor with Pigtail DIYAutoTune.com

Says it is for N/A applications because it reacts slower to IAT changes, i'd bet.
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Old 06-30-2015, 07:43 PM   #9
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Yeah i was looking for a napa equiv.

I found a thread earlier today that had some part numbers, but some were incorrect. After going back and forth with a few part #'s at napa none of the closed element had the connector I needed. I was able to get the open loop at napa for $25 (NIEHOFF IGNITION TS83631). The only reason I am rushing is I am running NASA HPDE @ Lime Rock on Friday.

The new sensor read ambient when I plugged it in. I'll install it tonight when the engine bay cools down & snap a picture of the fouled sensor. Thanks for everyone's help.

EDIT: I unplugged the bad sensor for the 20 mile drive home from work. I love that it defaults to 70* when there is an error. On an 80* day like today it ran just a smidge rich. Perfect!
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