PCV System Effects on Emissions and Driveability

Because PCV operation is factored into the proper operation of the feedback control system, problems with the PCV system may disrupt the normal air/ fuel ratio balance. A plugged PCV valve will prevent the normal flow of crankcase vapors into the engine and can result in a richer than normal air/fuel mixture. A plugged crankcase breather hose may cause the engine to consume oil because of the increased level of crankcase vacuum.

In addition, depending on the location of the fresh air breather hose, a nonfunctional valve or restricted vacuum hose can cause oil contamination in the air cleaner housing or throttle bore coking. Always suspect and check the PCV system if you find traces of oil in the air intake system.

If the crankcase becomes diluted with fuel, carbon monoxide (CO) levels will likely increase because the PCV system will meter extra fuel vapor into the intake system. Always replace fuel diluted engine oil and identify and resolve the problem causing the fuel contaminated.

Although there are no mandatory maintenance intervals for the PCV system, periodically check the system for a plugged or gummed PCV valve and damaged hoses. Replace suspect components as necessary. Since PCV flow rates differ between vehicle models, it is important to use the correct replacement PCV valve to ensure proper operation. The installation of an incorrect valve may cause engine stalling, rough idle and other driveability complaints. Thus, never install universal type PCV valves!

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    How does a pcv system affect emmisions?
    3 months ago

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