What are the reasons for BMW's cold engine shaking and stalling?
2 Answers
The reasons for BMW's cold engine shaking and stalling are: 1. Severe engine carbon buildup; 2. Ignition system malfunction; 3. Unstable oil pressure; 4. Aging engine components. Solutions for BMW's cold engine shaking and stalling: 1. Clean the fuel system and check the idle control valve for carbon buildup; 2. Replace the spark plugs; 3. Check the oil pressure and replace components; 4. Replace the engine's shock absorption system. BMW models include: BMW X3, BMW 5 Series, BMW X5, BMW M2, BMW M8, etc. Taking the 2020 BMW M8 as an example, it belongs to the full-size car category with body dimensions of length 5104mm, width 1943mm, height 1420mm, wheelbase 3027mm, fuel tank capacity 68L, and trunk capacity 440L.
I've been driving a BMW for years and often encounter severe shaking and stalling during cold starts. This is mostly caused by carbon buildup issues. A layer of black carbon deposits on the engine valves leads to uneven air-fuel mixture distribution during cold starts, resulting in unstable combustion and shaking. If the spark plugs have been used for several years, the enlarged electrode gap makes ignition difficult in low temperatures, easily causing misfires. The fuel system also needs attention - clogged fuel injectors or an aging fuel pump failing to deliver sufficient fuel pressure can make cold starts feel like starving for air. Additionally, when the coolant temperature sensor malfunctions, the car misjudges the temperature and causes air-fuel ratio imbalance. I recommend regular carbon cleaning, replacing old spark plugs (don't skimp on this), and avoiding overly thick engine oil like high-viscosity 10W-60 in winter as it increases starting resistance. These minor maintenance items cost little but can prevent major problems.
