In this research work, numerical studies are carried out for different injection timings to arrive at premixed charge compression ignition in a direct injection Diesel engine. Various models and submodels accounting for turbulence, combustion and emission formation, droplet spray, wall impingement and collision are considered. The flame propagation phase is modeled by solving the transport equation for flame surface density equation in extended coherent flame model for 3 zones. A sector model of the engine cylinder is taken to avoid expensive computational resources. Standard k-ε model is used for modeling the turbulent flow in the cylinder. The species equation is discretised by monotone advection and reconstruction schemes. PISO algorithm is employed for solving the Navier- Stokes equations. The CFD code is validated against experimental data and further investigations are performed on various injection timings from 6 deg before TDC to 30 deg before TDC. From the studies, it is found that oxides of nitrogen increases and soot decreases as injection is advanced.