What Causes the Car to Jerk When Starting?
3 Answers
When starting, especially when the engine is cold, the car jerks, which is usually caused by dirt on the throttle body. Below are the reasons why the car jerks when starting: 1. Carbon buildup causes the throttle valve to rotate less responsively, affecting the accuracy of the air-fuel mixture parameters or preventing sensors from accurately providing feedback to the servo. Cleaning the throttle body can resolve this issue. 2. It may be due to excessive carbon buildup in the engine. Below are the related symptoms caused by carbon buildup in different parts: 1. Cleaning the throttle body mainly addresses unstable engine idling and stalling. 2. Excessive carbon buildup in the combustion chamber: Increases the engine's compression ratio, creating multiple hot spots, leading to pre-ignition and knocking, shortening engine life, and significantly reducing engine power and fuel efficiency. 3. Carbon buildup on the fuel injectors: Causes uneven fuel injection across cylinders, resulting in engine shaking or stalling. 4. Excessive carbon buildup on spark plugs: Causes spark plug misfiring, leading to engine shaking. 5. Excessive carbon buildup on the throttle body: Causes unstable idling, reduced power, or even stalling. Check if the idle control valve has excessive carbon buildup, leading to this issue.
The car jerks when starting, and I think it's mostly due to clutch issues. This is more common in manual transmission cars. If the clutch disc is worn or not fully engaged, the car will shake like dancing when starting. Sometimes, improper operation, such as stepping on the accelerator too quickly or poor control of the semi-engaged clutch, can cause the car to speed up and slow down intermittently. I recommend checking it yourself first: gently press the accelerator when starting to feel the response. If the problem persists, it might be a damaged clutch pressure plate or a leak in the hydraulic system. Go to a repair shop immediately for inspection—don't delay, as it could damage the transmission and compromise safety. It's best to develop a habit of smooth starts and regularly replace the clutch disc, which saves both money and hassle.
Speaking of sudden jerks when starting the car, I've encountered it several times, usually caused by throttle control issues. For example, in automatic transmission cars, delayed throttle response can lead to either sudden jerks or sluggish acceleration. Common causes include dirty or clogged throttle bodies, faulty mass airflow sensors, or uneven fuel supply due to unstable fuel pump pressure. The inspection method is straightforward: first clean the throttle body, and if that doesn't work, check the fuel system. I once had it fixed at a 4S shop—cost a bit but solved the problem. Daily driving tips: avoid stomping on the accelerator and change the air filter regularly to prevent many issues.
