Car question

[tw]

Originally Posted by xoxoxoBruce

The engine management system gets input from several sources, ... Not all input is used to calculate all directions, only what's pertinent.

Pertinent to both engine speed and spark plug firing is one sensor. Typically a crankshaft position sensor or a camshaft position sensor. Computer uses that sensor to measure engine speed and determines when to fire spark plugs. How does a manifold vacuum sensor, throttle position sensor, air temperature sensor, Oxygen sensor, EGR position sensor, fuel pressure sensor, coolant temperature sensor, load sensor, or battery voltage measure engine speed?