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For ensuring environmental safety, strong emphasis on CO2 pollution reduction is mandated which led to evolution of miller cycle engines. However, the inherent Miller engine characteristic is the lower volumetric efficiency when compared to otto engines because of which small turbo chargers with variable geometry turbines are used to induct air into the engine. With miller engine and VGT turbo charger combination arises the challenges of charge controllability because of lower inertia and reduced vane control area. With conventional turbo charger control methods, the response time is slow thereby leading to turbo lag or severe over boosting, this is overcome by accurate engine modelling and using the same as input for charger control.

Precise control over mixture formation withhigh fuel pressure and multiple injections allows Gasoline Direct Injection (GDI) engines to be operated satisfactorily at extreme conditions wherePort Fuel Injection (PFI) engines wouldnormally struggle due to combustion instability issues. Catalyst heating phase is one such important condition which is initiated after a cold engine start to improve the effectiveness of the three-way catalyst (TWC). For a given TWC specification, fast light-offof TWC is achieved in the catalyst heating phase by increasing the exhaust gas temperature with higher exhaust mass flow. The duration of this phase must be as short as possible, as it is a trade-off between achieving sufficient TWC light off performance and fuel efficiency.