Why Does My Car Run Better With the PCV Valve Unplugged?

Unplugging a PCV valve may improve an engine's performance.

The PCV valve is the key component in the positive crankcase ventilation system. A defective PCV valve can cause a number of problems for an automobile engine. Though you can remedy these problems by unplugging the valve, your better option will involve replacing it.

Defective Valve Effects

A defective PCV valve will fail to vent exhaust gases in the engine. These gases will build up pressure inside the engine, causing oil leaks and other problems. A PCV valve that fails to work properly will restrict the amount of air entering the engine, causing idle problems and reducing fuel efficiency.

Unplugged Valve

If a car runs better with the PCV valve unplugged, the valve is likely not working properly and requires replacement. The unplugged valve allows the exhaust gases to vent through the valve opening, which reduces pressure in the engine from the exhaust gases.

Reasons to Replace

Unplugging the PCV valve can expose the engine to moisture and potentially harmful debris. The unplugged PCV valve allows exhaust gases to escape the engine, increasing vehicle emissions as well as restricting air flow to the engine and in turn causing a reduction in engine performance and an increase in fuel consumption.

References

• AA1Car: Library, Positive Crankcase Ventilation (PCV)