I have written before concerning a problem I had with my truck, and your repair suggestion was right on the money. I now have a question about something you mentioned in a recent column. In the article, you referred to a vehicle’s learned values for engine management. Would you mind expanding on that? Do these computers actually learn over time? How long does it take them to learn? What do they learn? Are they in all recent models?
Great question. My first experience with engine control memories was in the early 1980s with General Motors’ Computer Command Control system. Besides recording faults and setting trouble codes for later retrieval, the fuel injection system was smart enough to keep track of the amount of correction necessary to keep the exhaust oxygen sensor happy and apply the correction the next morning, even before the sensor woke up. This did wonders for cold engine drivability. The system also proactively corrected fuel delivery under all operating conditions, providing sweet and efficient performance. The control computer, called an ECM back then, also needed to keep an accurate memory of the idle control stepper motor position, or idle speed would become very wrong.
Modern vehicles go far beyond these baby steps, learning operator behavior, degraded component characteristics and environmental conditions, among other things. With advances such as electronic throttles, variable valve timing, variable geometry turbochargers and electronically shifted transmissions, system tracking and corrections constantly occur. These can be proactively applied to smooth performance, reduce emissions and stretch every drop of fuel. Many transmissions observe vehicle behavior when climbing a long hill and apply logic toward what may lie ahead. Shifts are also sweetened, based on earlier behavior, thanks to clutch or fluid irregularities. Air bag systems can also store “black box” information preceding a crash/deployment to assist in compiling facts afterward.