Just curious. This may be a foolish question (noob question), but if you were to tune the a/f ratio in Aug with summer heat, come winter when the air is more dense, do you need to re-tune to accomidate? Or is the computer making the correct changes? I thought of this last night because as we all know our cars run great when the temp drops.

 

You wouldnt need to re-tune. But you could to see if you pick up more power.

I assume most probably wouldn't especially if they have cold snowy winters, there isnt too much point to re-tuning cause you wont be gunning it on a snowy day, and most track probably wont be open.

I'm curious as to how much colder the air would be once the car is fully warmed, but I doubt anyone datalogged Air intake temperatures.

 

My thoughts were if the air fuel ratio stays the same, regardless of temp?

 

well an untuned or stock tuned car will try to remain as stoich as possible. But during the winter like you said, colder denser air, once the car is fully warmed I'm sure the outside air going into the car will get heated up, but I would assume not by as much since the air colder to begin with.

Back to your original question, if you didnt change your intake setup, and lets assume your filter didnt get any dirtier from august to Say November, you'll still take in the same amount of air. Only difference is the air will be a little denser. By how much is probably is a good question.

 

I believe the Ecu will make the adjustments for the air temp. We are setting up a 240Z for the Thunderhill 25 hr enduro and are possibly going to make a jet change at night if the motor leans out too much. The car has a wide band a/f meter in the car and it might be interesting to see how much it changes from day to night.

 

Temperature adjustments are implicit (ie not necessary for you to do) when using a MAF sensor system to determine air flow, since the sensor directly measures the mass flow rate of the air. Using a pressure sensor is a different story though.

 

Thanks DandyMax. Off of the top of my head, does the V-afcII use the MAP sensor and the S-afcII use the MAF? If this is correct, then should I be conserned using the V-afcII and not with the S-afcII? I apologize for being thick, but I'm just trying to figure out which fuel tuning system will suit me. Thanks again.

 

Either the VAFC or the SAFC will work.

The VAFC will read MAP to you instead of MAF % usage. But the 2 units will accomplish the same task (air fuel correction)

The VAFC is better than the SAFC in that sense(a/f tuning) , read the stickys on top of the All Motor page and you can see why.