What Causes BMW Engine Shaking When Starting Cold?
2 Answers
BMW engine shaking when starting cold can be caused by: 1. Faulty coolant temperature sensor; 2. Excessive carbon buildup on engine valves and intake ports; 3. Dirty throttle body or air flow meter. BMW models include: BMW X1, BMW 3 Series, BMW X5, BMW X6, BMW X7, etc. Taking the 2021 BMW X1 as an example, it is a compact SUV with body dimensions of: length 4565mm, width 1821mm, height 1620mm, and a wheelbase of 2780mm. The 2021 BMW X1 is equipped with a 1.5T turbocharged engine, delivering maximum horsepower of 140PS, maximum torque of 220Nm, and maximum power of 103kW, paired with a 7-speed dual-clutch transmission.
I've encountered this issue before - my BMW shakes like a sieve during cold starts. The main problems lie in the engine: First, carbon buildup clogs the intake valves, with oil accumulating in the manifold affecting the air-fuel mixture. Second, aging spark plugs or ignition coils cause unstable ignition, especially noticeable in subzero temperatures. Third, the throttle body gets as dirty as a rag, sticking and causing intake airflow fluctuations. Fourth, worn engine mounts with cracked rubber lose their damping effect. Fifth, fuel pump pressure leaks result in insufficient fuel pressure after overnight parking and uneven injection. BMW engines are precision instruments and particularly sensitive to carbon deposits. I'd recommend starting with a walnut blasting cleaning and replacing old spark plugs. If shaking persists, check the fuel pressure. Last time I cleaned the throttle body and saw immediate improvement.
