I have a 09 MCS with CAI and AP Stage 1 91 octane tune. This morning I hooked up my ultragauge to see what kind of boost psi I was getting and it peaked at almost almost 17 psi holding around 15 psi. It was 48 degrees outside. About a week ago I got 19+ psi peak but it was around 68 degrees ambient. Is the colder weather pulling my boost?

 

I know I get way better performance out of a dry 70-80 degree day than a mildly humid 50-60 degree day. Sometimes the air is just a bit too cold for the car to run perfectly...kinda like how room temperature water is better for hydrating than cold water, it's gotta be heated back up anyway to be used .

 

Thanks. I think ecu pulls boost when the temperature gets cold. Cold air is better for making power and the ecu limits boost to be safe.

 

Correct, ecu logic is load based, cold air(more dense) takes less boost to hit desired load target. A tuner will typically tune a car with load tables, as it automatically compensates to the environment like factory ecu logic.

 

Thanks!!! That's the info I was looking for.