I ran across an article today on Autospies.com that discussed a recent announcement from BMW of North America regarding turbo-lag problems with the twin-turbocharged inline six cylinder motor that currently powers the acclaimed 335i, among many other new BMWs.
From our perspective at RepairPal, what was interesting about the news is that BMW originally updated its engine software to address an engine noise problem, and in doing so, the new software fix created a small turbo-lag problem. This is a terrific example of the deep importance and extreme sensitivity of computer controls in modern automobiles. It wasn't long ago that a mechanic manually adjusted the air-fuel ratio and "tuned" an engine by listening to it run. Now, software can address the specific behavior of turbochargers so subtle that many drivers would probably not even notice it--in fact, the engine computer and emissions control systems are constantly measuring and varying every step in the combustion process. In other words, a modern car is constantly being tuned up by its engine computer.
This makes an auto technician's job harder. It takes a very firm understanding of automobile systems and the ways in which manufacturers manage those systems to properly diagnose and address problems. The article mentions that customers who noticed the turbo lag problem had their dealership service departments stumped. This is why we constantly reinforce how important it is to find an excellent diagnostic technician.