The firing order for most GM 4.3-liter V6 engines is 1-6-5-4-3-2. This sequence provides even ignition spacing across the two cylinder banks. Always verify with your specific vehicle’s service manual, as there can be year-to-year differences or model-specific variations.
Standard firing order and cylinder layout
The 4.3L V6 is a 90-degree OHV inline-six arrangement with two banks of three cylinders. When viewing the engine from the front, the left bank typically houses cylinders 1, 3, and 5, while the right bank houses cylinders 2, 4, and 6. The firing order 1-6-5-4-3-2 alternates between banks to keep timing even across the engine.
- 1
- 6
- 5
- 4
- 3
- 2
In practice, this means the sequence starts at cylinder 1 on the left bank, then fires cylinder 6 on the right bank, and continues alternating in the 1-6-5-4-3-2 pattern. Modern ignition systems (like coil-on-plug setups) follow the same firing order, but ignition components are arranged differently and controlled by the engine computer.
How to verify and apply this in maintenance
Using the correct firing order is crucial when installing spark plugs, wires, or performing ignition-timing work. If you’re replacing ignition components or hand-wiring a distributor, confirm the order with the factory service manual for your exact year, model, and engine code, as there can be small but important differences between production periods.
Notes on model-year variations
While the 1-6-5-4-3-2 sequence covers the vast majority of 4.3L V6 engines, some early vehicles or specialty vans/trucks may have variations due to distributor configuration or cam timing. Always cross-check with the vehicle’s VIN-specific service information or the dealer/GM service database for your exact engine code.
Summary
For most GM 4.3-liter V6 engines, the firing order is 1-6-5-4-3-2, with cylinder numbering typically organized as 1-3-5 on the left bank and 2-4-6 on the right bank when viewed from the front. Verify against your exact vehicle year and engine code to be certain, especially if you’re working on ignition components or timing equipment.