The Chevrolet 3.9L firing order is 1-2-3-4-5-6. That is the order GM lists in the factory service information for the 2008 Impala 3.9L. An earlier version of this guide gave a different order, and this update corrects it.
The 3.9L (236 cu in) is a V6 that GM’s order guides list for Chevrolet’s front-wheel-drive mid-size cars and minivans from the 2006 model year.
Chevrolet 3.9L firing order
The firing order is 1-2-3-4-5-6 in GM’s 2008 Impala 3.9L service information. GM’s order guides list three versions of the 3.9L: the LZ9, the LZ8 with cylinder deactivation (Active Fuel Management), and the LGD flex-fuel engine. If you have a different version, check the service information for your car.
Use the firing order when you trace a misfire code to a cylinder, or when you replace plugs and wires one at a time.
Chevrolet 3.9L cylinder numbers and layout
The engine is mounted sideways, so one bank faces the radiator and the other faces the firewall. There are cylinders 1, 3, and 5 on the rear bank, nearest the firewall, and cylinders 2, 4, and 6 on the front bank, nearest the radiator.
The rear-bank plugs sit close to the firewall and are the harder ones to reach, so plan for that before you start.
Chevrolet 3.9L vehicle applications
The RPO Archive’s LZ9 listing shows the 3.9L in these Chevrolet models:
- Chevrolet Impala (2006)
- Chevrolet Malibu (2006 to 2007)
- Chevrolet Monte Carlo (2006)
- Chevrolet Uplander (2006 to 2008)
GM’s order guides list the LZ8 for the 2007 Impala and the LGD flex-fuel version for the 2007 and 2008 Uplander. GM also used the 3.9L in models from other brands, such as the Pontiac G6 from 2006 to 2009.
Our take
For a 2008 Impala with the 3.9, GM’s service information gives 1-2-3-4-5-6, with odd cylinders on the rear bank and even cylinders at the front. Confirm the engine size on the emissions label first. The 3.5L in the same cars has its own Chevrolet 3.5L firing order guide.