Very interesting read. I'll share what I typically see in my datalogs.

I'm running AEM Series 2 (F/W 3.2), and I have O2 FB enabled during idle conditions. When I'm sitting at a light for a while (>60s), the IAT reading can increase by 30-40 deg F. During this time, O2 FB value will creep up and add fuel (typically the change is no more than 5-6%). I have my IAT fuel trim set up to 0% at 104 deg F, and +/- ~1.5% per every 18 deg F from the 0% point. My thought is that the increase in apparent IAT is causing the IAT fuel trim to take out fuel; however, the O2 FB is adding fuel to maintain the target AFR. If the IAT is truly rising, and the IAT fuel trim is accurate, then there shouldn't be any appreciable change in the O2 FB value. Some mentioned that IAT at idle condition could be quite different from IAT under normal driving conditions - I agree, as heat transfer at different flow conditions would be different. It would be interesting to be able to set up the IAT fuel trim based on IAT and RPM. I would almost zero out the IAT fuel trim at idle RPM, and increase its effect proportionally to RPM.

Just my thoughts.

 

I switched to a Bosch sensor and welded a boss to the ic pipe just after the ic so the sensor is out of the engine bay. Sensor works great and tells you exactly what the air temp is doing.

 

Sorry for the post revival, but do you know which bosch sensor you used?

Edit: hah, noticed this was my first post though i have been lurking here since 2013. Geez.

 

I never did this write up. Sorry guys. My car is for sale but I still have it so if anyone has any questions, please PM and I'll do my best to help.

 

But more info here >
https://www.s2ki.com/forums/s2000-fo...-yours-906417/

 

I HIGHLY recommend this sensor we sell. Put it in the IC piping, not the IM:

https://www.t1racedevelopment.com/product/t1-fast-at/