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Swirl valves

Swirl valves: Problems and troubleshooting

Many modern diesel engines are fitted with swirl valves in the intake manifold: small butterfly valves creating additional air turbulence in the intake. The purpose of this turbulence is to improve air-fuel mixing, theoretically improving low-end power and torque and reducing toxic emissions. In practice this only works well when the system is new and clean. If an engine is also fitted with a DPF and/or EGR system (like most modern engines), fouling in the intake manifold and on the swirl valves is very common. These tarry deposits restrict the movement of the flaps and consequently the airflow, having a direct negative impact on engine efficiency. This is exactly opposite of the original swirl valve's purpose! Chances of heavily contaminated swirl valves becoming stuck or otherwise faulty are likely. More seriously, the flaps or their mountings can fracture with parts entering a cylinder, causing major engine damage.

Signs of swirl valve malfunctioning:

  • Output power reduced
  • Engine management system problems (error codes)
  • Starting problems
  • Rough idle
  • Major engine damage (secondary)

Commonly applied solutions are:

  • Clean the air intake and swirl valves
  • Replace parts
    (often expensive and non-repetition of the problem cannot be guaranteed)
  • Complete swirl valve removal
    (hardware removal and fitting of blanking plates to maintain manifold sealing)
  • Combination(s) of the above

KCPerformance can troubleshoot swirl valves for you. This starts with precise diagnostics;
we are equipped with the tools to read error-codes from all brands, supplemented by our practical experience.