Homogeneous Charge Compression Ignition (HCCI) engine is a newly introduced technology. However, controlling the HCCI timing of ignition and theheat release rate, at all operating regimes, present the biggest challenge due to the complicated and highly coupled combustion problems. The successful implementation of the common rail injection system in diesel engines has made this possible. The main key for this success is the capability to optimize the most important fuel injection parameters, namely timing, rate, and duration.This work experimentally investigates the performance of an HCCI Diesel engine with a Common Rail Direct Injection (DI) fuel system. The engine used is a turbocharged 2776 cc, 4-stroke, 4-cylinder, water-cooled with overhead valve mechanism. The engine performance is evaluated and presented at different loads and speeds. The Apparent Heat Release Rate during combustion is evaluated from the measured cylinder pressure-crank angle data. The pressure in the fuel line is measured at the entry to different fuel injectors to investigate the effect of pressure wave propagation in the fuel line on the fuel injection system.