Plastic has various advantages and is becoming more ubiquitous by the year, yet recycling and disposal remain challenges for the world. We conduct tests in this study to evaluate the appropriateness of various Plastic Pyrolysis Oils (PPOs) made from Low Density Polyethylene (LDPE), High Density Polyethylene (HDPE), and Polypropylene (PP) for diesel engine fuel. Determine which type of plastic pyrolysis oil would function best as an alternative fuel in an experimental investigation. The elemental composition of pyrolysis oil generated from LDPE, HDPE, and PP to diesel was assessed, tabulated, and compared in this study. This study examines emission characteristics (Nitrogen Oxide (NOX), Hydro Carbon (HC), and Carbon Monoxide (CO)) for Diesel, LDPE, HDPE and PP in CI engines using different injection pressure, compression ratio, and load in a specific configuration. In the result of experimental work the CO emission range for diesel and LDPE is exceeded only during overload situations or when the engine load is 100%. The average NOX emission is lowest when PP is used in comparison to other fuels, and the highest NOX emission occurs when LDPE is utilised as a fuel. Increased fumigation rates may be to blame for the rising hydrocarbon content of plastic oil. Unburned hydrocarbon levels are lower at lighter loads due to increased oxygen availability. The use of this whole pyrolysis oil results in a significant decrease in Nitrogen Oxide (NOX), Hydro Carbon (HC), and Carbon Monoxide (CO) exhaust emissions. With the help of this current study. one can solve plastic waste disposal problem and also find any unknown fuel (PPOs) that can be used as an alternative fuel for CI engine or not.