Okay, I'm stupid. What is the ECU and why must it be reset after installing Stillen intakes? Or, the battery disconnected? Dealer (what do they know) says after about 100 miles with new intakes, computer teaches itself??

If the battery is disconnected, is that going to screw up navi, etc.?

 

An ECU is an electornic control unit. It's a computer that does what the name says, namely control almost every functon of the car including air fuel/ratio, throttle, and many, many more of the car's fucntions. It is set to certain parameters from the factory that are slightly "detuned" from all that the car could achieve if it were programmed a little more agressively. This is to enhance reliability but at a slight cost in performance.

Resetting it causes it to "relearn" everything after you turn the engie on and run it again. Hence, it will relearn things with the modificatins you made (e.g. exhaust, intake, etc.) and not in stock form. This is not the greatest description but I hope it helps.

Disconnecting the battery does not hurt anything, although you'll likely lose radio presets and things like that.

 

I posted the ECU reset process in FAQ DIY section.

 

Sounds like a pretty good description to me

 

How long do you have to leave the battery dissconnected?

 

I don't know the minimum time, but most leave it overnight and it always resets. So 8 hours will do it for sure, but I've heard as little as 2 hours.

 

You don't really need to reset it. Just start driving and the ECU will adapt to the new mods after a while.