Why does the Passat engine shake during cold start?
3 Answers
The root cause of the Passat shaking during cold start is poor combustion in the cylinders. When combustion is poor, the vehicle cannot provide sufficient power, resulting in shaking. Detailed explanations for engine shaking during cold start are as follows: 1. Excessive carbon deposits: When there is too much carbon buildup inside the engine, the gasoline sprayed by the cold start injector is largely absorbed by the carbon deposits, leading to an overly lean air-fuel mixture during cold start and causing the engine to shake. 2. Fuel quality: Poor fuel quality not only affects the overall performance of the engine but also causes long-term damage and shortens its lifespan. Therefore, it is recommended that car owners avoid using low-quality fuel for temporary savings and not blindly use higher-octane gasoline. Instead, they should choose the appropriate fuel grade as specified in the vehicle manual.
I've been using this Passat for several years, and every time I start the engine cold, it shakes violently, like sneezing with a cold. It's mainly due to issues with the fuel system, such as excessive carbon buildup in the fuel injectors, which affects the uneven spraying of gasoline. When the weather is cold, gasoline may not flow smoothly, making the engine run unevenly. I've also encountered problems with aging spark plugs, which lack the strength to ignite properly, causing the car to shake when starting. Ignoring these issues can lead to a significant increase in fuel consumption and damage to the engine. It's recommended to regularly clean the fuel injectors or replace the spark plugs. If you do it yourself, spraying some cleaner can help alleviate the problem, but it's best to go to a professional shop for a thorough check to prevent minor issues from turning into major troubles.
I just got my new Passat not long ago, and I get nervous every time the engine shudders during startup, worrying if it's broken. A friend said it's mostly likely an issue with the ignition system—maybe the spark plugs are worn out or there's a leak in the high-voltage wires, which is more prone to happen in cold weather. It could also be a clogged air filter not allowing enough air intake, making the engine struggle and shake. It's not hard to check—just take it to the 4S shop for a computer diagnosis. This shouldn't be delayed, as driving with a shaky engine is unstable, especially dangerous on slippery winter roads. I’ll get it fixed early for peace of mind on the road.
