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Variable valve timing has existed for many decades. Honda made the system famous in the late 1980s, and it has since become a common feature on many import and domestic vehicles.



What is a Valve Timing Solenoid?

If you suspect your VTEC, VVT-I, MIVEC, or CVTC system isn’t functioning properly, the problem may be due to a malfunctioning valve timing solenoid.

The acronyms above refer to the same thing: variable valve timing systems. Manufacturers made up unique names for their systems even though they all function in the same way. Although many modern engines will start and run without one, all variable valve timing systems require a functional solenoid for their engines to run properly.

How do Variable Valve Timing Solenoids Work?

Certain cam profiles work well for producing power at low RPMs, and other cam profiles work well for producing power at high RPMs. Variable valve timing lets engines switch between cam profiles based on how fast the engine turns.

The valve timing solenoid allows the engine management system to seamlessly change between these profiles as the engine accelerates. The solenoid uses an electrical signal from the engine management system to act on the engine’s cams. When acted upon, the cam profile changes, resulting in more usable power as the engine speed increases.

How are Valve Timing Solenoids Made?

A solenoid is a motor designed to push a rod or other component when it receives an electrical signal. Valve timing solenoids are mass-produced using factory machinery. It is all but impossible to replicate this part at home without significant engineering and machine shop capabilities.

Why do Valve Timing Solenoids Fail?

  • Dirty engine oil due to infrequent oil changes gums up the solenoid and causes it to seize.
  • Electrical signals may not reach the solenoid, causing it to malfunction.

What are the Symptoms of Valve Timing Solenoid Failure?

  • Check engine light comes on and stays on.
  • Lack of power at higher RPMs.
  • No idle, rough idle, or sputtering at low RPMs.
  • Marked decrease in fuel economy.

What are the Implications of Valve Timing Solenoid Failure?

  • Decreased fuel economy increases operating and maintenance costs.
  • Inefficient combustion at higher RPMs increases carbon deposits on valves and piston crowns, accelerating wear on those parts.
  • Major valvetrain damage may occur if the solenoid comes apart inside the cylinder head.

Variable valve timing enables small, fuel-efficient engines to make impressive amounts of power. The solenoid is a key part of all variable valve timing systems that needs to be maintained.

If you have questions or concerns about valve timing solenoids or any of your vehicle’s components, come into your local Pep Boys where we can answer any question, help you find any part, or perform any vehicle service you might need.