Abstract: A method of initiating a neutral tow feature in a four-wheel drive vehicle. To initiate the neutral tow feature, an input signal is received from at least one signal generating device. Thereafter, it is determined if the at least one signal indicates that a precondition has been met. If the precondition has been met, then the neutral tow feature is automatically engaged.

Abstract: A method for monitoring the performance of a catalytic converter (34) computes the oxygen storage capacity and desorption capacity of a catalyst within the catalytic converter (34). An engine control unit (10) receives mass flow rate information of air from a mass air flow rate sensor (12) and an injector driver (24), and receives electrical signals from an upstream exhaust gas sensor (28) and a downstream exhaust gas sensor (30). A rate modifier is determined from excess air ratios and an adaptation parameter. The engine control unit (10) calculates normalized air fuel ratios for the exhaust gas entering and leaving the catalytic converter (34) and performs numerical integration using the rate modifier to determine the oxygen storage capacity of the catalyst in the catalytic converter (34). The calculated oxygen storage capacity of the catalyst can be compared with threshold values to determine the performance of the catalytic converter (34).

Abstract: A system and method of detecting a leak in an evaporative emissions system for a vehicle includes measuring a physical disturbance of the vehicle with a sensory system and providing a sensory signal (311, 313, 315). Then, comparing the sensory signal (311, 313, 315) to a threshold (405) and generating a diagnosis signal (407, 413) having a "valid test" state, when the sensory signal does not exceed the threshold, and generating the diagnosis signal having an "invalid test" state, when the sensory signal exceeds the threshold. And, executing an evaporative emissions system leak test while the provided diagnosis signal indicates the "valid test" state, and aborting the evaporative emissions system leak test (505) when the diagnosis signal indicates the "invalid test" state.

Abstract: A method and system of misfire determination includes establishing an acceleration misfire threshold and an acceleration sub-misfire threshold. Then incremental engine position is sensed and a series of acceleration data-points are derived (401). If a data-point of the series of acceleration data-points falls between the sub-misfire threshold and the misfire threshold, then a training process is aborted for a blanking period based on a delay time whose length is preferably based on engine operating conditions (415). If a data-point of the series of acceleration data-points does not fall below the sub-misfire threshold, then the series of acceleration data-points, are averaged and a synchronously corrected acceleration data-point is derived (417). Then, a misfire condition is indicated when the synchronously corrected acceleration data-point exceeds the established acceleration misfire threshold (421).

Abstract: The catalyst control method of the invention continuously estimates a level of oxygen stored by a catalyst within a catalytic converter. The estimated oxygen stored by the catalyst is compared to a predetermined threshold and positive or negative deviations in the oxygen amount from the threshold is determined. When a positive deviation from the threshold amount is detected, the air/fuel ratio flowing into an engine (16) is decreased. Correspondingly, when a negative deviation is detected, the air/fuel ratio flowing into the engine (16) is increased. The amount of oxygen stored by the catalyst is determined by analyzing signals from a first gas sensor (28) positioned upstream from a catalytic converter (34) and a second gas sensor (30) positioned downstream from the catalytic converter (34). An engine control unit (10) integrates an expression for the mass flow rate of excess oxygen into the catalytic converter (34).

Abstract: A method for monitoring and controlling the performance of a catalytic converter (34) includes monitoring an exhaust gas stream from an engine (16) for the presence of methane. Upon detecting methane in the exhaust gas stream an oxygen storage level of a catalyst within the catalytic converter (34) is determined. The oxygen storage level is compared with a reference standard and the air/fuel ratio of the exhaust gas stream is continuously adjusted to maintain the oxygen storage level within predetermined control limits.

Abstract: A method and system for adaptive transient fuel compensation in a cylinder of a multi-cylinder engine estimates fuel puddle dynamics for the cylinder by determining parameters of a wall-wetting model every engine cycle of the multi-cylinder engine. Fuel delivery to the cylinder is adjusted dependent on the estimated fuel puddle dynamics.

Abstract: A method and system for adaptive transient fuel compensation in an engine (300) estimates fuel puddle dynamics for a cylinder in an engine by determining parameters of a wall-wetting model on every engine cycle by measuring a temporal delay (407) between when an identification fuel charge is injected (405) and when a binary-type exhaust gas oxygen sensor (213) switches state. Fuel delivery to the cylinder is adjusted (417) dependent on the estimated fuel puddle dynamics which are a function of the measured temporal delay (407).

Abstract: A method and system for fuel delivery to an engine (400) measures when an exhaust gas sensor (413) is in a non-lit-off condition and when the exhaust gas sensor is in a lit-off condition. A control device (409) estimates fuel puddle dynamics for an intake system of the engine when the exhaust gas sensor is in the lit-off condition, and adapts (511) an open-loop fuel parameter table (229) dependent on the estimated fuel puddle dynamics. The control device (409) adjusts fuel delivery to the engine dependent on the fuel puddle dynamics when the exhaust gas sensor is in the lit-off condition, and adjusts fuel delivery to the engine dependent on the open-loop fuel parameter table (229) when the exhaust gas sensor is in the non-lit-off condition.

Abstract: A method and system for adaptive transient fuel compensation in a cylinder of an engine (300) estimates a fraction of fuel evaporated in a fuel intake system of the engine (b.sub.v) by measuring a temporal delay (515) between when an identification fuel charge is injected (505) and when a binary-type exhaust gas oxygen sensor (315) switches state. An estimate of a fraction of fuel adhering to the fuel intake system of the engine (c) is derived from the estimate of evaporation wall-wetting parameter (b.sub.v). Fuel delivery to the engine is adjusted dependent on the estimates of the adhering wall-wetting parameter (c) and the evaporation wall-wetting parameter (b.sub.v).

Abstract: A method and system for adaptive transient fuel compensation in a cylinder of a multi-cylinder engine estimates fuel puddle dynamics for the cylinder by determining parameters of a wall-wetting model every engine cycle of the multi-cylinder engine. Fuel delivery to the cylinder is adjusted dependent on the estimated fuel puddle dynamics.