Edit / Update Part 3 - My car was still running inconsistently and the Relocate IAT sensor seemed to be a temporary fix. I did more maintenance on it with new Iridium Spark Plugs, Cleaned the MAP sensor, changed the interference suppression ground cable, fuel injector cleaner, reset the adaptations and it has been running like a champ with the stock IAT Sensor. Seems like the AA Tune which was created on the Stock IAT sensor works better with less aggressive trims and corrections than when the Relocate IAT is installed. So if you have a good healthy running car this modification will not do much as shown by Biginboca.
Edit/Update Part 2 - I figured out the OBDlink to some extent so did some more data logging at night
Later on that night - Driving at 80 Degree Temps per dash
MAF at Idle 111.2f - Short Stop light
MAF at Speed 100.4f - Cruising
MAF at Speed 96.8f - Extended Cruise
MAF Graph from Stop to Cruise
IAT Relocate At idle 91.4f - Long Stop Light
IAT Relocate at Speed 82.4f - Cruising
IAT Relocate at Speed 80.6f - Extended Cruise
IAT Relocate Graph from Stop to Cruise
Like I said this mod has not made the car gain power - just feels more consistently the same liveliness and torqueness, like it feels first thing in the morning from dead cold.
Edit/Update Part 1 - I purchased an OBDlink LX and tried it at work.
Quick Test Idling at my Job - Ambient 95 Degree Temps per dash
I ran the MAF first showing 180-190f Coolant Temps
MAF Readings were 144f at idle / 136f after revving at 2600rpm for 30 seconds
I ran the IAT Relocation second showing 195-205f Coolant Temps
IAT Relocation Readings were 113f at idle / 107f after revving at 2600rpm for 30 seconds
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Hey Folks. I recently acquired a cool 330i 6MT with modifications - MILVs / SS Headers / AA Tune / Euro Intake / Scoops - that I noticed ran significantly better when it was first driven when completely cold. 20-30 minutes later after it was beyond warm and heat soaked it would lose a lot of its torque and quickness. I looked into reasons for this and there are a lot of older generation cars that had heat soak issues remedied by relocating the Intake Air Temperature sensor. I did this mod to my car and it made a huge difference in how it idles and runs. It is not quicker or more powerful, just more consistently the same no matter how hot it gets or how long I have driven it.
In some of those older generation cars that did this trick the sensor was already a stand alone part and so they lengthened the harness wire and placed it towards the front of the chassis. In our N52 it is integrated into the MAF sensor. Turner Motorsports makes a plug and play kit with wire harness adapater (although I found the wire length for the new IAT Sensor short) for the N52 that comes with an appropriate Bosch Sensor.
Many people with that did this mod to their M3 / M5 found that it ran smoother and that it more so maintained that power and torque felt at cold start up. I do not have any ECU diagnostic software or OBD connection so I can not provide before and after data. There is a good amount of that data out there that suggests the IAT when relocated and not heat soaked should read a few degress to maybe 15 degrees max higher than the Ambient Air Temp. There is also data out there that shows the stock location MAF based IAT sensor reads temperatures from 25-55 higher than Ambient Air Temp.
I used an EV1 plug extension to get my sensor to reach in front of the radiator support in the snorkel entrance so that it would not be affected by the heat of the radiator and radiator fans. The Turner / ECS Tuning setup seems to reccommend placing the sensor in the front snorkel entrance of the air box, which is above the radiator and affected by the radiator fans, which from my infared gun temperature reading shows to be very hot around 141 degrees.
The parts - EV1 Plug extension not shown
The EV1 Plug extension I bought - It is super cheap quality - Might get a custom one made:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
I deleted some of the infared temp gun readings as they were confusing / miscontruing the information being conveyed.