1 Nov 2014

Yesterday the boost-by-gear was fine-tuned and then the car parked. Today the weather was about 10 deg F cooler and now it keeps hitting the boost limit. It’s not surprising: the air is cooler and more dense, the ECU adds more fuel, which produces more exhaust, and up goes the boost right into the limiter. Sigh… KPro doesn’t have the ability to do closed-loop boost control. That is, the driver programs boost control valve values and hopes that boost ends up somewhere near the target. A more capable ECU works the other way round: target boost is specified and the ECU adjusts the wastegate to make it so. The beauty is that it self-compensates for engine temperature, weather, and altitude. Now I know.