Commodore (VN-VZ) / HSV

1988-2006 / Sedan / Estate / Australia

All Commodore (VN-VZ) / HSV problems All workshop issues

Critical Engine, V8 (LS1 5.7L / LS2 6.0L, VT-VZ)

DOD/AFM Lifter Collapse (VZ LS2 with DOD)

Symptoms

Misfiring on specific cylinders, rough idle, check engine light. Metallic knocking from inside the engine.

Cause

The VZ LS2 (some models) features Displacement on Demand (DOD), which deactivates four cylinders under light load. The DOD lifters use an internal locking mechanism that can fail, causing the lifter to collapse and the valve to not open. This is a known GM design issue affecting LS engines with DOD/AFM worldwide.

Fix

Replace the failed lifters.

Many owners replace all lifters with non-DOD lifters and have the DOD system disabled via an ECU tune.

This is the recommended long-term fix, it eliminates the problem permanently.

Parts: $300-500 for non-DOD lifters.

Tune to disable DOD: $200-400.

Cost mentioned in fix

$300-500 for non$200-400

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// More Commodore (VN-VZ) / HSV problems

Other known issues

Common Engine, V8 (LS1 5.7L / LS2 6.0L, VT-VZ)

Lifter Tick

Light ticking noise from the top of the engine, usually on cold start. May or may not persist once warm.

Common Engine, V8 (LS1 5.7L / LS2 6.0L, VT-VZ)

Valley Cover Oil Leak

Oil pools in the "valley" between the cylinder banks, visible when the intake manifold is removed. Oil may weep from the manifold area externally.

Common Engine, V6 (Buick/Ecotec 3.8L, VN-VY)

Intake Manifold Gasket Leak

Coolant leak at the junction of the intake manifold and cylinder heads. May present as coolant loss without a visible external leak (coolant enters the intake ports), or as a coolant stain on the side of the engine. Engine may run rough or misfire if coolant enters the combustion chamber.

Critical Engine, V6 (Buick/Ecotec 3.8L, VN-VY)

Harmonic Balancer Failure (Ecotec, VS onwards)

A wobbling pulley on the front of the crankshaft. Knocking or rattling noise from the front of the engine. The drive belt may track poorly or come off.

Common Engine, V6 (Buick/Ecotec 3.8L, VN-VY)

Supercharger Bypass Valve Failure (L67 supercharged V6)

Loss of boost, rattling from the supercharger, reduced performance. The supercharger may make a whining noise that changes with the valve's operation.

Critical Engine, V6 (Alloytec 3.6L, VZ)

Timing Chain and Guide Failure

Rattling noise on cold start that may persist after warm-up. Check engine light with codes related to camshaft timing. Rough idle, misfiring, loss of power. In severe cases, the engine won't start or runs extremely poorly.

View all 20 Commodore (VN-VZ) / HSV problems