What is the firing order of an engine?
2 Answers
The firing order of an engine: 1. For a three-cylinder engine, the firing order is 1, 3, 2; 2. For a four-cylinder engine, the firing order is 1, 2, 4, 3 or 1, 3, 4, 2; 3. For a five-cylinder engine, the firing order is 1, 2, 4, 5, 3; 4. For an inline six-cylinder engine, the firing order is 1, 5, 3, 6, 2, 4 or 1, 4, 2, 6, 3, 5; 5. For a V6 engine, the firing order is 1, 4, 5, 2, 3, 6 or 1, 6, 5, 4, 3, 2; 6. For an eight-cylinder engine, the firing order is 1, 8, 4, 3, 6, 5, 7, 2.
Over the years running this auto repair shop, the most frequently asked question is about engine firing order. Simply put, it's the sequence in which cylinders fire in rotation. For four-cylinder engines, common orders are 1-3-4-2 or 1-2-4-3, while six-cylinder engines typically use 1-5-3-6-2-4. Why this specific firing sequence? Mainly to ensure balanced engine forces – if it's messed up, vibrations increase dramatically, making the car shake like a tractor. During repairs, I've noticed incorrect firing orders make exhaust smell abnormal and frequently trigger dashboard warning lights. Each vehicle's firing order is stamped on the engine cover label and must be followed during major overhauls. Some newer models even have ECU self-learning functions that automatically correct firing sequences if they get mixed up.
