What Causes the Car to Shake After Starting?
1 Answers
There are three main reasons why a car shakes after starting: 1. Low ignition energy: The first issue a car faces during a cold start is low temperature. The engine's internal temperature is insufficient, and both fuel and lubricant temperatures are low. Therefore, more fuel needs to be injected during a cold start to meet power requirements. The larger the spark plug gap, the lower the ignition energy. Poor fuel atomization at low temperatures requires higher ignition energy. Over time, the spark plug's ignition gap tends to widen, reducing ignition energy and affecting performance, causing the car to shake. 2. Carbon buildup on valves and intake passages: If carbon accumulates on the engine's valves and intake passages, it absorbs some fuel, leading to ECU miscalculations. For example, if the ECU controls the injection of 100 units of air-fuel mixture but only 90 units enter the cylinder, even complete combustion of these 90 units won't achieve the required power, resulting in shaking. 3. Incorrect air-fuel ratio: Inaccurate air-fuel mixture ratios can occur in both open-loop and closed-loop control systems. In closed-loop control vehicles, the oxygen sensor's minimum operating temperature is 370°C. If the exhaust pipe temperature doesn't reach 370°C upon starting, the oxygen sensor won't function. This causes the ECU to make errors in controlling the air-fuel mixture and ignition timing, reducing the car's power output and causing shaking.
