Method and system for controlling an internal combustion engine when such engine loses a primary crankshaft position sensor

This invention relates generally to engine control systems, and more particularly to engine control systems adapted for controlling an engine upon loss of such engine's primary crankshaft position sensor. A method and system for controlling an internal combustion engine system upon loss of a crankshaft position sensor signal produced by such system is provided. The method includes providing a control module having a central processing unit and a time processor unit associated with such central processing unit. The time processor unit has programmed into is a first code for operating the engine system in the presence of a proper crankshaft position sensor signal. The control module stores a second code for loading into the time processor unit to operate the engine system with the time processor unit upon detection of an improper crankshaft position sensor signal. Initially, the engine system is operated with the time processor unit executing the first code. The method monitors the crankshaft position signal for a fault. Upon detection of the fault, the method loads the second code into the time processor unit and operates the engine system with the time processor unit executing the second code.