What are the reasons for engine shaking during cold start?
2 Answers
Reasons for engine shaking during cold start: 1. Low ignition energy at low engine temperature, insufficient temperature inside the engine, and inadequate temperature of both fuel and lubricating oil. More fuel injection is required during cold start to meet power requirements; 2. Inaccurate air-fuel mixture ratio adjustment, which occurs in both open-loop and closed-loop control systems; 3. Carbon deposits on engine valves and intake ports; 4. Variations in spark plug ignition gap and timing control; 5. Malfunctioning coolant temperature sensor; 6. Dirty air flow meter resulting in reduced air intake; 7. Poor working condition of the exhaust gas recirculation valve, introducing exhaust gas during idle; 8. Poor fuel quality failing to meet the required calorific value, leading to reduced combustion power output.
I've discussed this issue quite a few times in the car enthusiasts group. When the car shakes during cold starts, it's mostly due to problems with the ignition system, such as aging spark plugs or loose ignition coils. Carbon deposits can interfere with ignition when the engine is cold, leading to unstable combustion and shaking. The fuel system is also a suspect—clogged fuel injectors or low fuel pressure can cause insufficient fuel supply at low temperatures. On the air intake side, a dusty air filter or a faulty intake sensor can disrupt the air-fuel mixture ratio. Additionally, engine oil becomes very thick in cold weather, leading to inadequate lubrication and jerky piston movement. These aren't major issues, but if left unattended, they can accelerate engine wear and increase fuel consumption. Regular maintenance, including checking spark plugs, changing engine oil and air filters, and cleaning carbon deposits, can prevent these problems.
