What Causes Engine Shaking in a BMW X5?

[McCaleb]

There are several reasons for engine shaking in a BMW X5: 1. Low ignition energy causing shaking. When the engine temperature is too low, both fuel and lubricant temperatures are low. During startup, a richer air-fuel mixture is required, which demands higher ignition energy. Excessive spark plug gap, aging ignition coils, or high-voltage coils can all lead to reduced ignition energy, resulting in vehicle shaking. 2. Incorrect air-fuel mixture ratio causing startup shaking. Due to significant signal errors from certain engine sensors or some sensors, the ECU makes incorrect judgments. This leads to errors in fuel injection timing and ignition timing control, causing engine shaking. 3. Uneven cylinder conditions causing engine shaking. In multi-cylinder engines, significant differences in ignition energy among cylinders, as well as varying degrees of piston and piston ring wear leading to inconsistent compression ratios, can result in uneven engine power output and engine shaking.