What Causes Jetta to Shake at Idle but Not When Accelerating?

[LeCharlie]

The reasons for Jetta shaking at idle but not when accelerating include issues with the ignition system and the need to clean the throttle body. Specific details are as follows: Ignition System Issues: Spark plugs have a limited lifespan. If the spark plugs have been used for a long time, they may not fire properly, leading to unstable idle conditions. Therefore, it is essential to inspect the ignition system, including the spark plugs, to determine if they need replacement or if there is excessive carbon buildup. If such issues are found and are causing the idle shaking, the spark plugs should be replaced or cleaned promptly. Throttle Body Needs Cleaning: The proper functioning of the throttle body directly affects the engine's performance. During vehicle operation, carbon deposits can accumulate in the throttle body. Excessive carbon buildup can obstruct the engine's normal air intake, resulting in insufficient engine power to drive the compressor or barely managing to do so. In such cases, when starting the car and turning on the air conditioning, idle shaking may occur. Hence, it is crucial to check the throttle body for cleanliness and clean it if necessary.