What is the reason for the Passat shaking when cold but not when hot?
2 Answers
Passat shaking when cold but not when hot is most fundamentally caused by poor fuel quality leading to incomplete combustion in the cylinders. Incomplete combustion results in insufficient power output, causing the vehicle to shake. Here are the specific details: 1. Poor fuel quality not only affects the overall performance of the engine but also causes damage to the engine over time, shortening its service life. 2. It is recommended not to opt for cheap, low-quality fuel for temporary savings, nor to blindly use higher-grade gasoline. Instead, choose the appropriate fuel grade as specified in the vehicle manual.
I've been driving a Passat for many years, and it's common to experience shaking when the engine is cold but not settling down when it's warm. This could be due to a faulty ignition system, excessively large or aged spark plug gaps, leading to poor ignition performance when cold, causing the shaking; once the engine warms up and components become more flexible, it smooths out. Other issues like carbon buildup in the intake system causing uneven air and fuel mixture, or a malfunctioning coolant temperature sensor failing to adjust the proper mixture, can easily expose problems during cold starts. I believe regular maintenance is key—checking the cleanliness of the fuel injectors or replacing spark plugs can reduce those awkward shaking moments. Long-term neglect can also increase fuel consumption or accelerate engine wear, so it's better to take it to a 4S shop for a check-up sooner rather than later.
