I just received a new MS3-Basic from Reverant and am a bit confused on how to configure the IAT. In our PMs back and forth while it was being built, he said I had to use the GM IAT in place of IAT2 (the one just before the TB). However, This Thread suggests the stock IAT2 can be used as-is, at least with a Megasquirt built by DIY Autotune.

The GM sensor will require cutting wires and drilling/tapping something on the cold side of the intercooler before the TB. I want to avoid that if at all possible. These may be questions that only Reverant can answer, but I figured I'd post this here for other MSM/NB2 owners.

Questions:

1. Is the MS3-Basic already configured to use the wiring from IAT2, or does it use the MAF wiring like on NA/NB1 cars?
2. Is an MS Labs IAT bias resistor the same as the one in the MSPNP DIY Autotune sells (2490ohms)?
3. Has anyone successfully used the stock IAT2 with an MS Labs MS2 or MS3?

I figure as long as my MS3B is configured to use IAT2 wiring (or it's a simple software change) and it uses the same resistor (or I can find the value), the curve below should work just fine.

Stock IAT2 curve points from the other thread:

• -4F - 357k
• 32F - 112k
• 68F - 41k
• 77F - 33k
• 104F - 17k
• 140F - 8k
• 185F - 3.5k

 

You want to use the GM ait because it responds way faster than the mediocre OEM MSM one. To answer your other questions: you can use the OEM, just re-calibrate it. But I'd stick with GM if you have one

if you don't want to cut wires, just make a pigtail for the gm with pins on the end, stick em into the oem plug and tape em up. if you do it right, it will work (I've done it) and easily reversible.

 

theres no reason to cut wires to install the gm.

1. probably.
2. yes
3. yes. i have done it on one ms3x i built, its no biggie.

 

Thanks for the quick response. Is your GM sensor the same thread as the stock MSM one? Someone in that other thread I linked said he had to drill and tap the IAT2 bung on his car.

I don't have the sensor yet, but they're cheap locally. I have a pigtail for the GM sensor, but I haven't bought pins (or better yet, a pigtail to connect to the stock harness).

 

different thread iirc