Getting a smooth MAP signal with quick response is very important for getting an engine to run smoothly and responsively. In order to get a smooth signal it is necessary to set the crank angle at which the MAP sensor is sampled. The MS3 firmware provides a method to set the angle across the engine's RPM range. That method is described here.
This section describes the MAP sampling settings.
There are two main types of settings:
Because of the various mechanical, sampling, and other minor inconsistencies that go along with a running engine, the MAP sensor is not only sampled one time at the specified angle. The angle specified in the MAP sample timing curve specifies the start of MAP sampling for a particular sampling event, at which time, the MAP sensor is sampled for the duration specified in the MAP Sample Window.
During the MAP Sample Window, the MAP sensor is sampled every 0.128 ms for the duration of the MAP Sample Window angle specified. Each sample is compared with the previous sample, and the lowest value between the two is stored temporarily. At the end of the sampling window, the value that was stored temporarily will contain the lowest value sampled during the whole window. This value is then used for all table lookups and calculations that involve MAP.