What Causes the Shaking When Starting a Newly Purchased Audi A4L?
1 Answers
In theory, a new car should not shake, and it is recommended to have it inspected at a 4S shop. The fundamental reason for the shaking phenomenon during cold starts or when starting in neutral is poor combustion in the cylinders. Incomplete combustion and low ignition energy result in insufficient power output from the engine, causing the car to shake. The reasons for low ignition energy and insufficient power are as follows: 1. Incorrect Air-Fuel Ratio: An incorrect air-fuel ratio can occur in both open-loop and closed-loop control systems. In a closed-loop control environment, the oxygen sensor's minimum operating temperature is 370 degrees Celsius. However, when the car is just started, the exhaust pipe temperature does not reach 370 degrees Celsius, and the oxygen sensor does not begin functioning. As a result, the ECU makes incorrect judgments, leading to errors in ignition timing control through the actuators, which reduces power output and causes the car to shake. 2. Carbon Buildup on Engine Valves and Intake Ports: If there is carbon buildup on the engine valves and intake ports, the carbon deposits absorb fuel. Even if the remaining fuel burns completely, it may not provide the required power, making the shaking phenomenon unavoidable.
