This paper describes the engine mapping work carried out on a 2.1 litre carburetted petrol engine.The purpose of this work was to improve upon the emission levels of the engine to meet 1996 emission norms with sufficient margin and to achieve best fuel economy possible. This paper deals with the strategy for the selection of speed load points required for mapping depending on engine operating zones, engine base data collection, methodology followed in engine mapping, variation of engine performance and emissions with respect to air/fuel ratio and spark timing etc. Further the mass emission predictions for different strategies like leaning the air/fuel mixture, retarding the ignition timing etc. are also discussed. Recalibration of the carburettor based on the above findings, its effect on vehicle performance are dealt with. Finally, the comparison between predicted and actual mass emission figures, driveability and fuel consumption achieved along with the conclusions derived are also discussed.