Abstract: A method of monitoring exhaust gas flow through an exhaust system of an internal combustion engine comprising the steps of generating a flow efficiency value (KE), comparing the flow efficiency value to a reference efficiency value, and if the reference efficiency value is exceed by a predetermined amount, then setting a flow fault indicator flag. In one aspect of the invention, the flow efficiency value is generated as a ratio of the magnitude of the exhaust gas flow restriction, and the mass flux through the engine. The magnitude of the exhaust gas flow restriction is represented by the pressure drop across the exhaust system, and the mass flux through the engine is determined as a function of the mass airflow rate and exhaust gas density. The resulting flow efficiency value (KE) is a non-dimensional parameter that characterizes the level of restriction in the exhaust system independent of the engine operating conditions.

Abstract: A cold start fuel preheat system for an internal combustion engine includes a housing and a fuel rail extending through the housing to deliver fuel to the internal combustion engine. The cold start fuel preheat system also includes a phase transform material disposed in the housing and about the fuel rail. The cold start fuel preheat system further includes a mechanism for heating the phase transform material such that the phase transform material stores the heat and transfers the stored heat to the fuel during cold start of the internal combustion engine.