Abstract: A method is disclosed for detecting misfire or partial burn and for controlling spark retard in the cylinders of an internal combustion engine operated under the control of a microprocessor and utilizing signals indicative of the pressure in said cylinder at crank angle positions before and after initiation of combustion. A ratio of the actual pressure to the motored pressure in the cylinder at one or more predetermined crank angles is used to estimate the fraction of fuel burned which, in turn, enables a determination of combustion failure in said cylinder cycle. Confirmation of said misfire or unacceptable partial burn leads to correction of engine operation by said controller and/or to a diagnosis of possible damage to the vehicle's catalytic converter. This method also permits better engine operation under conditions of high spark retard.

Abstract: A control for an internal combustion engine by pressure ratio management. The ratio of combustion chamber pressure to motored pressure is determined for several predetermined crankshaft rotational angles. These pressure ratios are used to control ignition timing for MBT, diluent gas flow rate (EGR) and fuel balance among combustion chambers. The control requires from three to five pressure samples for each combustion event, depending on sensor and control options. The pressure sensors need not sense absolute pressure if they are linear and do not change gain or bias significantly during one cycle.

Abstract: A control for an internal combustion engine by pressure ratio management. The ratio of combustion chamber pressure to motored pressure is determined for several predetermined crankshaft rotational angles. These pressure ratios are used to control ignition timing for MBT, diluent gas flow rate (EGR) and fuel balance among combustion chambers. The control requires from three to five pressure samples for each combustion event, depending on sensor and control options. The pressure sensors need not sense absolute pressure if they are linear and do not change gain or bias significantly during one cycle.

Abstract: A control for an internal combustion engine by pressure ratio management. The ratio of combustion chamber pressure to motored pressure is determined for several predetermined crankshaft rotational angles. These pressure ratios are used to control ignition timing for MBT, diluent gas flow rate (EGR) and fuel balance among combustion chambers. The control requires from three to five pressure samples for each combustion event, depending on sensor and control options. The pressure sensors need not sense absolute pressure if they are linear and do not change gain or bias significantly during one cycle.