Method and apparatus for monitoring a valve deactivator on a variable displacement engine

Apparatus for determining if a valve deactivator on a variable displacement internal combustion engine is functioning properly comprising:

• a computer;
• sensor means supplying data to said computer;
• said computer using said data for calculating fuel mass for two cylinder banks of the engine during fractional mode of engine operation and during maximum mode of engine operation;
• said computer detecting when a difference between a fractional mode calculation for one cylinder bank and a fractional mode calculation for the other cylinder bank exceeds a stored value,
• said computer detecting whether the absolute value of a difference between a maximum mode calculation for one cylinder bank and a maximum mode calculation for the other cylinder bank is less than a stored value;
• said computer storing a valve deactivator fault code both of said differences are detected.

A method for determining if a valve deactivator on a variable displacement internal combustion engine is functioning properly comprising the steps of:

• checking for an asymmetry in a fuel mass calculation between two cylinder banks of said engine during fractional mode of engine operation;
• checking for substantial symmetry in the fuel mass calculation between the two cylinder banks of the engine during maximum mode of engine operation;
• storing a valve deactivator code if an asymmetry exists during said fractional mode and substantial symmetry exist during said maximum mode;
• wherein a predetermined number of checks for asymmetry must be performed in order to make a decision on whether to store said code;
• wherein fractional mode asymmetry must exist for a predetermined percentage of the number of checks for asymmetry;
• wherein the code stored identifies the bank of cylinders where the asymmetry exist;
• and
• wherein asymmetry exist if a difference exist between a ratio of short and long term correction factors on one bank of cylinders and a ratio of short and long term correction factors on the other bank of cylinders and said difference exceeds a calibratable value.