What causes increased exhaust pipe vibration frequency?
2 Answers
Reasons for increased exhaust pipe vibration frequency: 1. Intake manifold or various valve leaks - incorrect air intake can cause excessively rich or lean air-fuel mixture, leading to abnormal engine combustion; 2. Excessive carbon deposits or dirt on throttle body and surrounding intake passages - changes in air passage cross-sectional area prevent the control unit from precisely regulating idle air intake; 3. Incorrect air intake measurement - the control unit receives erroneous signals from air flow sensors and issues wrong commands, resulting in inaccurate idle air intake, abnormal mixture concentration, and consequently abnormal engine combustion, which are indirect causes of unstable idle.
I encountered a similar issue during the last maintenance. Common culprits are a few worn-out parts. Rubber exhaust hangers tend to harden, age, or even break over time, causing the exhaust system to lose cushioning effect—you'll notice the entire pipe shaking when going over speed bumps. If the gasket at the exhaust pipe connection deteriorates or bolts loosen, it leads to gas leakage accompanied by localized high-frequency vibrations. A failed engine mount rubber block is more troublesome, transmitting engine vibrations directly to the exhaust system, making even the steering wheel shake. Modified cars require extra attention, especially those with oversized exhaust tips that alter the center of gravity—the stock hanger positions may not withstand the stress, leading to wobbling. It's advisable to first inspect the chassis for hanger conditions before screws snap and puncture the undercarriage.
