I know that there are many sensors that are constantly changing things to make the car run it's best / cleanest, such as the knock sensor, IAT sensor, and so forth. How much can these hold back powerwise?

In the day at around 75* the car feels like a pig compared to at night at around 60*. I know that colder air is denser and all that but it really feels like a night and day differance. I know it's not in my head because I always hit it on this one road by my house and during the day, it feels quick but like it's still missing something. At night, though, it really pushes me back in the seat and feels like I just threw on some headers or something.

I doubt there's anything wrong with my sensors since I have no codes but I was just wondering how much the PCM can hold back the car's real output.

 

You answered your own question ... colder denser air and all that, is all that. The PCM is not holding you back.

A 10* to 15* difference can mean as much as 2-3 tenths at the track ... depending on humidity, barometric air pressure and which way the wind is blowing ...

 

Wow, didn't know that such a slight change in temp could equal that much of a differance. I always figured it would have to be a bigger gap (like 90* compared to 50*) to even notice anything SOTP.

I was thinking before more towards the way that the colder air is creating less knocking with the gas I run ( 91, California) so it allows more timing, because the most noticeable increase comes later in the powerband (over 4k) and that is where it would be affected the most, right?

BTW .1-.2 is almost 10-15 hp isn't it, going by the (probaly false) rule of 100 lbs.=10 hp= .1 of a sec. That would definently be noticeable.

 

the rule of thumb i've always heard when talking about cold air induction is for every 10deg drop in intake air temp, you get a 1% increase in performance.

so if the air is 20deg cooler outside ambient...than that is a 2% increase in power...so on a 300hp engine that's 6hp.

now the key to this (which ricers dislike) is that it's a percentage. THEY like to think that a CAI will give any car...no matter the hp...the same boost in power.
that is why they think a CAI on a 120hp honda will give them 10-15hp...when in the real world...you barely get that in a 300+ hp car.