This research paper aims to compare an engine's probable and contemporary condition concerning performance, combustion, and emission characteristics to identify obstructions and assess the suitability of deactivating the cylinder. A 998 cc three-cylinder spark-ignition, multi-point fuel-injection engine with an open engine control unit that features normal and cylinder deactivation modes has been selected. Experimentation was carried out at a constant speed of 3000 rpm under three load conditions: 15, 30, and 45 N m. The result shows that 45 N m acts as full engine load when two cylinders are active. Consequently, a reduction in pumping loss during deactivation mode facilitates brake-specific fuel consumption drops by 11.55% and brake thermal efficiency rises by 3.18%. In deactivation mode, peak pressure has been observed to be 1.75 times that of the conventional method, where the maximum heat release rate was 1.82 times that of the normal mode. The fraction of mass burned during cylinder deactivation is higher for all crank angle levels. It indicates an enhanced combustion rate and a higher degree of combustion efficiency than those in normal mode. An increase in average gas temperature in deactivation mode facilitates the catalytic converter to work effectively and efficiently. In deactivation mode, unburned hydrocarbons are reduced significantly, while carbon dioxide reduction is 13.86% at 30 N m. This research paves the path for adopting cylinder deactivation mode in smaller engines and offers prospective benefits such as better fuel usage, enhanced engine performance, more efficient combustion, and reduced pollution levels.