tuning in relation to weather conditions(temp, ect)

[Cirus_93TSI]

i might be along in not understanding this, but i would like to know how the weather(tempature, barometric pressure, ect) affects your tuning.

i got my jdm longblock in a few weeks ago, and its been nasty cold since then so i have had to tune it in cold weather. yesterday was fairly warm and my car ran like crap on the way to work, so i retuned my fuel a little on my lunch and did a log run and it seemed to run better.
but what gets me is that i couldnt go below +12 idle in the cold and stay in closed loop, but since i tuned it a little on the warn day its at +7 at idle and stays in closed loop. same goes for the rest of my low map, i set everything a few precent lower on the afc and it runs fine(even in the cold), even though those settings didnt run good before.

but that being beside the point, i would like to know how outside temp and pressure affect the tuning of our cars. ie. how does it affect the o2 voltage? will warm tuning run good i cold weather? what temp is most desirable to tune at?(seeing as i will run the car much more at nite then during the day, track days are rare, and street races are very common)

and im sure there are some other things about this that im forgetting to ask, but if anyone has any insight on this topic i would like to hear it.

thanks, brian

 

[kpt4321]

The MAF *should* compensate for any and all temperature changes, so you really shouldn't see a difference.

You can usually push the car harder in the cold, because the charge air is cooler (less chance of detonation) and the intercooler is more efficient.