A variety of methods and arrangements for reducing noise, vibration and harshness (NVH) in a skip fire engine control system are described. In one aspect, a firing sequence is used to operate the engine in a skip fire manner. A smoothing torque is determined that is applied to a powertrain by an energy storage/release device. The smoothing torque is arranged to at least partially cancel out variation in torque generated by the skip fire firing sequence. Various methods, powertrain controllers, arrangements and computer software related to the above operations are also described.

A method for diagnosing a part of a powertrain system is provided. The powertrain system comprising an internal combustion engine system having an internal combustion engine provided with a plurality of cylinders, each cylinder being provided with an air inlet valve and an exhaust gas valve, the method comprising the steps of operating any one of the inlet valve and the exhaust valve for any one of the cylinders to adjust the frequency and/or duration of air pulses during different load conditions of the internal combustion engine; determining an operational behaviour of the part of the powertrain system in response to the adjusted frequency and/or duration of the air pulses; and comparing the determined operational behaviour of the part of the powertrain system with an expected behaviour of the part of the powertrain system.

A method, for an internal combustion engine including an intake camshaft equipped with a variable intake valve timing device including an intake timing actuator and an exhaust camshaft equipped with a variable exhaust valve timing device including an exhaust timing actuator, of detecting inverted connection of the intake timing actuator with the exhaust timing actuator, including: measuring the angular position of the intake camshaft and the angular position of the exhaust camshaft; commanding one of the two timing actuators according to a setpoint and keeping the other of the two timing actuators immobile; measuring the angular positions of the intake camshaft and of the exhaust camshaft; and comparing: if the angular position of the camshaft corresponding to the timing actuator that's been commanded has not been modified, and if the angular position of the camshaft corresponding to the immobile timing actuator has been modified, inverted connection can be diagnosed.

A method of operating an engine is provided. An exhaust valve actuation fault is detected for a first exhaust valve associated with a first cylinder during a first working cycle. In response to the detection of the exhaust valve actuation fault, fueling to at least the first cylinder is cut off. Actuation of the first exhaust valve is attempted in second working cycles that follow the first working cycle, wherein the second working cycles are not fueled. Whether or not the first exhaust valve actuated properly during the second working cycles is determined. Operation of the first cylinder is resumed when it is determined that the first exhaust valve actuated properly. Operation of the first cylinder is not resumed when it is determined that the first exhaust valve did not actuate properly.

A neat-fuel direct-injected compression ignition engine having a thermal barrier coated combustion chamber, an injection port injects fuel that satisfies a stoichiometric condition with respect to the intake air, a mechanical exhaust regenerator transfers energy from exhaust gas to intake compression stages, an exhaust O.sub.2 sensor inputs to a feedback control to deliver quantified fuel, a variable valve actuation (VVA) controls valve positions, an exhaust gas temperature sensor controls exhaust feedback by closing the exhaust valve early according to the VVA, or recirculated to the chamber with an exhaust-gas-recirculation (EGR), heat exchanger, and flow path connecting an air intake, a load command input, and a computer operates the EGR from sensors to input exhaust gas according exhaust temperature signals and changes VVA timing, the load control is by chamber exhaust gas, the computer operates a fuel injector to deliver fuel independent of exhaust gas by the O.sub.2 signals.

An engine assembly and a method of control thereof is provided. The engine assembly comprises: an exhaust gas aftertreatment device having an inlet for receiving exhaust gases leaving an engine; a heater for selectively heating gases at or upstream of the exhaust gas aftertreatment device; an air moving device for driving a flow of gases into the inlet of the exhaust gas aftertreatment device when the engine is in a non-running condition; and a controller configured to, prior to the engine being started: operate the heater to heat gases at or upstream of the inlet; and operate the air moving device to drive a flow of gases into the inlet to thereby heat the exhaust gas treatment device.

A vehicle includes an engine having an intake manifold and an exhaust manifold. An exhaust system is connected to the exhaust manifold and has an aftertreatment device. The aftertreatment device has a body defining inlet and outlet cones, a heating element, and a catalyst disposed in the body between the cones. An air-circulation system has conduit extending from downstream of the catalyst to the intake manifold and an air-circulation device configured to circulate air from the outlet cone, through the conduit to the intake manifold, through the engine, to the inlet cone, and through the aftertreatment device.

A method of reducing cold start emissions in a series mode hybrid electric vehicle, including an internal combustion engine with an exhaust duct having a catalyst and a downstream oxygen sensor, an output of the combustion engine being connected to an electric generator with a power output of at least 10 kW that is connected to an electric motor which is coupled to a drive shaft of two or more wheels. The method includes detecting a cold start condition, injecting fuel into the engine such that combustion at a lambda value, λ, is achieved for which λ>1, running the engine at a speed of 1000 rpm or higher, determining if the efficiency of the catalyst reaches a first level, setting λ to about 1 after the predetermined efficiency level of the catalyst has been reached, and reducing the speed to working conditions when the catalyst efficiency reaches a second level.

Methods and systems are provided for an engine for adjusting cylinder parameter settings to optimize engine output during a transient mode. In one example, a method may include adjusting cylinder parameter settings, including a cam timing setting, a spark timing setting, and a fuel injection timing setting based on a chamber temperature in response to a rate of fuel injection acceleration being greater than a positive threshold, thus indicating the engine is in the transient mode.

A vehicle includes an engine having an intake manifold and an exhaust manifold. An exhaust system is connected to the exhaust manifold and has an aftertreatment device. The aftertreatment device has a body defining inlet and outlet cones, a heating element, and a catalyst disposed in the body between the cones. An air-circulation system has conduit extending from downstream of the catalyst to the intake manifold and an air-circulation device configured to circulate air from the outlet cone, through the conduit to the intake manifold, through the engine, to the inlet cone, and through the aftertreatment device.