What Causes Shaking When Starting an Automatic Transmission Car?
2 Answers
The reasons for shaking when starting an automatic transmission car are: 1. The throttle is too dirty, causing uneven air intake and operation; 2. Fuel line obstruction, leading to insufficient fuel supply at low throttle and uneven operation of engine cylinders; 3. Abnormal transmission operation; 4. Broken or burnt high-voltage wires or spark plug breakdown causing some cylinders to misfire, resulting in unstable engine operation; 5. Battery voltage is outside the specified range. The correct starting sequence for an automatic transmission car is: 1. Turn the ignition key to the power position to initiate the car's computer system self-check for about 6 seconds; 2. Press the foot brake, shift the gear from P to N, release the foot brake, then turn the ignition key to the start position to fire up the engine; 3. Press the foot brake, release the handbrake, shift from N to D gear, and slowly release the foot brake to start moving.
Having driven automatic transmission cars for decades, I've encountered numerous cases of shaky starts. The most common culprit is unstable engine idling, typically caused by worn spark plugs or aging ignition coils - improper ignition timing makes the engine tremble. Transmission issues are also frequent offenders, such as torque converter lock-up clutch failures or degraded/dirty transmission fluid that disrupts smooth power delivery. Sometimes clogged fuel injectors or severe carbon buildup create uneven fuel injection patterns that induce shaking. Worn engine mount rubber components that can't absorb vibrations will amplify the shuddering sensation. Through experience, I've found regular maintenance is crucial - inspecting spark plugs and fluids every 5,000 km prevents these issues. Left unaddressed, prolonged shaking increases fuel consumption and accelerates part wear, so early detection and intervention saves both hassle and money.
