Why does my integra with a b20 swap 5 speed, run alot faster when its cold? is it the extra fuel that helps? or maybe the person who did the swap didn't tune it for the 2.0 fuel maps?

 

normal, basic equation is cooler air charge = more hp

usually the engine runs a bit faster when either engine is cold which is not recommended for example on a vtec motor vtec wont engage until ecu reads engine is at op temp. Or on a very cold night you will experience the engine runs a bit fast hence the colder air charge that gives more fuel and timing added from the ecu.

 

Exactly. In the winter time ANY car will get worse gas mileage because it needs more fuel for ignition. Hence active forced cold air intakes actually add power. (putting a cold air filter under your hood without cold air actively getting to it, will not add power because of under hood temps) However, in any owners manual, it will tell you not to drive aggressive on a cold engine.