Reasons for Jetta's Jerky Start When Cold, Like Fuel Starvation?

[LaStephanie]

Reasons for Jetta's jerky start and fuel starvation: 1. Low engine temperature: Especially during cold starts in winter, the temperature inside the engine is insufficient, and both fuel and lubricant temperatures are low. Therefore, more fuel should be injected during cold starts to meet power requirements. Poor fuel atomization at low temperatures leads to decreased ignition energy, affecting power output and causing the car to shake. 2. Carbon deposits in the engine and intake tract: Carbon deposits can absorb an appropriate amount of fuel, causing the ECU to make incorrect judgments. For example, if the computer controls the injection of 100 units of air-fuel mixture, but only 90 units actually enter the cylinder, with 10 units being absorbed by carbon deposits, even if the remaining 90 units burn completely, the required power output still cannot be achieved. 3. Ignition system failure: Aging of the ignition system leads to weakened ignition energy, causing the ignition coil or spark plugs to fail to fire continuously or resulting in intermittent ignition. This discontinuous ignition prevents smooth and continuous power output, leading to the jerky acceleration phenomenon.