What causes rough idling and poor acceleration related to the purge control valve in a Mercedes-Benz E-Class? Detail:

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What causes rough idling and poor acceleration related to the purge control valve in a Mercedes-Benz E-Class? Detail:

Lately, my Mercedes E-Class has been idling roughly and the acceleration feels sluggish. A mechanic mentioned it might be due to the purge control valve not functioning correctly. Can a faulty purge valve cause vacuum leaks o r fuel vapor issues leading to these symptoms? How common is this problem for E-Class cars in Pakistan’s conditions?

Talha Kyanii asked on 11 Oct 2025 13:57:50 pm

1 Answer

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Gari Master - on 11 Oct 2025 13:58:50 pm

A malfunctioning purge control valve can cause rough idling and poor acceleration due to:

Vacuum leaks: If the valve leaks vacuum when it shouldn’t, the air-fuel mixture is disrupted, causing unstable idle and hesitation.

Incorrect vapor flow: When the valve fails to regulate fuel vapor flow properly, the engine can run either too rich o r too lean.

Fuel vapor flooding: Excess vapors during acceleration can overwhelm the combustion process, reducing power.

In Pakistan, dusty environments and inconsistent fuel quality can exacerbate purge valve wear o r clogging, leading to these symptoms. Cleaning o r replacing the valve typically resolves the issue.