what does a mechanic do exactly when he "tunes" your car performance wise not maintenance...?

 

Adjusts the ECU's parameters to make better use of the air and fuel your car is able to injest, usually comprised of leaning the car out and adding timing, but that is it in it's simplest form.

Scorke

 

pretty much a perfect answer

 

how often do you need to tune? i have SRI, hi flow cat, and catback. do i tune now and then get a piggy back then tune again or should i just wait?

how much gain can one expect from a tune and how much would it cost

 

If you are going to get a tune do not get a piggyback ECU it in effect does the same sort of thing. Get a tune after you put most of your performance items on. Usually though a NA car is only going to be able to be tuned to a certain point before it is no longer suitable for a daily driver.

 

+1 I have a very aggressive tune and cam on my ES... on hot days idle lopes bad enough people think there is something seriously wrong with the car. I dont mind it tho. My 85 Mustang was a lot worse. Had to 2 foot it anytime it got over 75°.

 

75 is a cold day in Miami

 

Basically winter temps

 

Come up to norther Indiana right now... we'll have a cookout and all... and you can enjoy the 61° weather.