Mis-Fire Dectection

[Christopher G. Moog]

Dave J. Andruczyk wrote:

> Well this isn't directly related to the chrysler system.  But there is a
> feedback addon for carburted cars that uses a hall effect sensor that
> looks at the flywheel teeth,  a misfire will cause a change in angular
> velocity of the teeth, ( and thus the pulses outputted by the hall
> sensor).  A change in angular velocity (assuming no other inputs to the
> engine are changing) will show a misfire.  If the computer had other
> position input info ( cam position/crank position) the computer would
> probably be able to figure out which cylider misfired.
>
> Dave

  Since OBDII requires misfire detection numerious schemes have been
developed.  The ones measuring changes in engine speed (from crank sensor)
incorporate signals from the ABS wheel sensors since rough roads can cause
false readings.