System and method for diagnosing output power of an internal combustion engine

A method of estimating actual output power of an internal combustion engine mounted in a vehicle and connected to a transmission having a number of selectable gear ratios, the engine having a fueling system responsive to fueling signals to fuel the engine, means for a providing the fueling signals and an engine speed sensor responsive to engine speed to provide an engine speed signal, and a means for sensing vehicle speed and providing a vehicle speed signal corresponding thereto, the method comprising the steps of:

• starting and warming up the engine;
• engaging the engine with a numerically low gear ratio of the transmission;
• accelerating the vehicle along a drive path and through a desired engine speed range while collecting one of engine speed and vehicle speed data;
• coasting the vehicle along the drive path and through a desired vehicle speed range corresponding to the desired engine speed range while collecting vehicle speed data;
• and
• processing the speed data collected during the accelerating and coasting steps and computing therefrom an estimate of actual engine output power over the desired engine speed range.

A method of estimating actual output power of an internal combustion engine mounted in a vehicle and connected to a transmission having a number of selectable gear ratios and a clutch for engaging and disengaging the gear ratios, the engine having a fueling system responsive to fueling signals to fuel the engine, means for a providing the fueling signals, an engine speed sensor responsive to engine speed to provide an engine speed signal and a vehicle speed sensor responsive to vehicle speed to provide a vehicle speed signal, the method comprising the steps of:

• engaging the engine with a numerically low gear ratio of the transmission;
• accelerating the vehicle along a drive path and through a desired engine speed range under maximum engine fueling conditions while collecting one of engine speed and vehicle speed data;
• coasting the vehicle along the drive path and through a desired vehicle speed range corresponding to the desired engine speed range with the clutch disengaged while collecting vehicle speed data;
• and
• processing the speed data collected during the accelerating and coasting steps and computing therefrom an estimate of actual engine output power over the desired engine speed range.

A method of diagnosing output power of an internal combustion engine having a number of cylinders, a fueling system responsive to fueling signals to fuel the engine and means for providing the fueling signals, the method comprising the steps of:

• providing means for sensing engine speed and providing an engine speed signal corresponding thereto, and means for sensing vehicle speed and providing a vehicle speed signal corresponding thereto:
• investigating existence of a low engine output power condition and performing the following steps only if said low engine output power condition exists,
• correcting relative compression values of each of the number of cylinders having a relative compression value below a predefined relative compression value,
• adjusting the fueling signals to balance a relative contribution to engine output power of each of the number of cylinders:
• and
• operating a vehicle carrying the engine along a drive path and estimating therefrom an actual engine output power over a desired engine speed range, including:
• accelerating the vehicle along the drive path and through the desired engine speed range while sensing one of engine speed and vehicle speed:
• coasting the vehicle along the drive path and through a desired vehicle speed range corresponding to the desired engine speed range while sensing vehicle speed:
• and
• processing the speed information sensed during the accelerating and coasting steps and computing therefrom estimate of the actual engine output power over the desired engine speed range.

A method of diagnosing output power of an internal combustion engine having a number of cylinders, a fueling system responsive to fueling signals to fuel the engine and means for providing the fueling signals, the method comprising the steps of:

• investigating existence of a low engine output power condition and performing the following steps only if said low engine output power condition exists:
• correcting relative compression values of each of the number of cylinders having a relative compression value below a predefined relative compression value,
• altering the fueling signals to cut fuel delivery to one of the number of cylinders;
• accelerating the engine:
• computing an engine acceleration rate while accelerating the engine:
• altering the fueling signals to cut fuel delivery to different ones of the number of cylinders and repeating the accelerating and computing steps to thereby compute an engine acceleration rate while fuel delivery is cut to a different one of each of the number of cylinders;
• comparing engine accelerations rates computed with fuel cut to each of the number of cylinders and computing therefrom a corresponding relative output power contribution of each of the number of cylinders;
• adjusting the fueling signals to equalize the relative output power contribution of each of the number of cylinders to overall engine operation;
• and
• operating a vehicle carrying the engine along a drive path and estimating therefrom an actual engine output power over a desired engine speed range.