1. Significant difference in compression ratio and amount of fuel in the cylinders. 2. Air is in the fuel pipes. 3. The engine is not installed correctly or the mounting bolts are loose. 4. Piston knocking causes uneven operation.
1. Check and adjust. 2. Remove air. 3. Level the engine and retighten the bolts. 4. Check the injectors and fuel supply advance angle, make the necessary adjustments.