Genuine Nissan Swirl Control Valve

Suit GU Patrol with ZD30 Common Rail Engine

The swirl control valve is installed inside the manifold assembly at the rear of the manifold. While idling and during low engine speed operation, the swirl control valve closes, thus the velocity of the air in the intake passage increases to produce a swirl (rush of air to promote cleaner burning when the fuel is injected into the air) into the combustion chamber. Once the engine speed increases to a certain speed, the valves open to allow more air to enter the engine.

These aren't known to become faulty and not function correctly.