MS1 PNP - Trouble with AFR.

[hellyn]

Hello, I´m new to MS and I´m trying to learn as I go along.

I have a 1990 MX5 (miata) wich I´ve installed a MSPNP, IAT and LC1 on.
I´ve set a AFR Target table and I´ve used autotune in TunerStudio to tune it so that I can drive it a little.
I haven´t used the car for a month, so today I went and started it. WUE was very good, a little rich, but that´s better then lean. I drove around the city and AFR was good.
The problem I have is that the AFR changes after a while. Today it got rich (12) when cruising. I had then driven the car for 30 mintues. I know that the IAT-sensor gets heatsoaked, but then shouldn´t the AFR be leaner ? (If the engine thinks it´s getting warm air that is not that dense, it would put in less fule and the AFR would be higher because that air was acctually dense and cold).

Anyway.
What am I doing wrong here? If I use autotune to get the AFR just right, It´s way off the next time I go for a drive.

[Matt Cramer]

Please also post a data log. This will give us more to go on.

[hellyn]

Ok. Sure thing.
The log was to big to upload here, so I uploaded it to my site:

http://dekorfabrikken.no/mspnp/2015-01-17_13.29.21.msl
This is from dead cold engine. Drove around the city. Then downhill and uphill for a while..

After half an hour I stopped logging and started a new log:
http://dekorfabrikken.no/mspnp/2015-01-17_13.58.36.msl

[Matt Cramer]

How accurate are those IAT readings?

[hellyn]

It was about 0 Celsius outside. The IAT sensor is positioned in the area above the exhaust. So I´m guessing it will get heat soaked.
But shouldn´t reading be lean if the MS is tricked by a heat soaked IAT sensor?