What are the reasons for severe engine shaking during vehicle startup?

[GeorgeMarie]

The reasons for severe engine shaking during vehicle startup are: 1. Dirty throttle body; 2. Excessive carbon buildup in fuel injectors; 3. Poor ignition system performance with weak spark plug firing; 4. Abnormal fuel pump pressure; 5. Faulty readings or malfunction of the intake pressure sensor; 6. Worn engine mounts. The solutions for severe engine shaking are: 1. Clean or replace the air filter; 2. Use a multimeter to measure resistance and replace wires with high resistance; 3. Maintain engine operating temperature within normal range; 4. Clean fuel injectors; 5. Replace spark plugs; 6. Clean fuel system and idle control valve; 7. Replace engine mounts.