A new breed of mechanics has begun hacking into car computers, and grease monkeys have morphed into automotive geeks.

To tune up the first generation of computer-controlled cars, drivers bought chips with new engine maps from a handful of tuning companies. But because the chips were hard-wired, car owners were limited as to the changes they could make. They couldn’t custom-program their cars.

Though not intending to, carmakers added that ability in the mid-1990’s. They replaced the Eprom chips with rewritable flash memory like the memory used in digital cameras. And to meet environmental laws for California, they added a data port to all cars, allowing inspectors to access the engine-control unit and assess whether the engine was operating cleanly.

By plugging in a laptop, car hackers could download engine maps from the E.C.U.’s memory, modify them and upload the changes without touching a soldering iron. “That’s when what had been a fledgling tuning industry started to flourish.”

[Read](http://www.nytimes.com/2006/10/25/automobiles/autospecial/25hacking.html?ex=1319428800&en=c36bc89385305f9c&ei=5090&partner=rssuserland&emc=rss “Read the Story”) (New York Times)