Why does the engine shake when starting and then stall?
4 Answers
The main reasons for engine shaking are as follows: 1. This is the most common cause of engine shaking, and the problem lies in the engine ignition coil or spark plug. If the ignition coil malfunctions or the spark plug fails to fire for some reason, the car will experience shaking. Misfiring is also a relatively easy fault to diagnose. If the car shakes significantly more than usual during medium to low-speed operation and feels sluggish during acceleration, it can generally be concluded that the engine is misfiring. 2. If severe carbon buildup inside the cylinder causes the engine spark plug or valves to clog, the engine will also experience shaking. If the car's acceleration performance has significantly declined and the shaking is persistent, it may be necessary to consider cleaning the engine cylinder.
I've encountered this situation several times. When the engine starts cold, it shakes violently and then stalls, mostly due to fuel or electrical system issues. Last time my car had this problem, it was caused by excessive carbon buildup on the spark plugs leading to poor ignition, and it was fixed after replacing the spark plugs. Another time, I found that the fuel injector was clogged, preventing proper fuel atomization. A dirty mass air flow sensor can also cause the engine control unit to miscalculate the fuel supply. For older cars, special attention should be paid to insufficient fuel pump pressure—if fuel isn't delivered properly, the engine will naturally stall. If this happens in summer, check if the charcoal canister purge valve is stuck. It's best to connect an OBD scanner to read the fault codes, so you don’t end up replacing three or four parts like I did before finding the real issue. I recommend first checking the ignition coils and spark plugs, and cleaning the throttle body to see if that helps.
This issue can range from minor to serious. I encountered it while helping a neighbor fix their car. The engine would sputter a few times upon starting and then stall. Common causes include leaks in the intake system or a faulty EGR valve causing leaks. An imbalanced air-fuel ratio leading to a lean mixture can cause shaking. This is especially likely with poor fuel quality, and using low-grade gasoline that clogs the fuel injectors can also cause sudden stalling. Newer cars might experience this due to issues with the electronic throttle—if the throttle position sensor fails, it can't accurately measure the opening. In my own car, it was a failed crankshaft position sensor that caused the problem; replacing the sensor fixed it. Also, remember to check if the battery terminals are loose, as insufficient power causing large voltage fluctuations during startup can lead to similar symptoms.
My mechanic friend said this situation requires step-by-step troubleshooting. If the starter motor is fine but the engine won't start, focus on the fuel supply system and ignition system. A fuel filter unchanged for 20,000 km can easily clog and restrict fuel flow. Cracked ignition coils can leak electricity causing cylinder misfires and shaking. For cold starts in winter, check if the coolant temperature sensor readings are accurate - incorrect signals affect fuel injection volume. Worn engine mount bushings can transmit severe vibrations to the cabin. A completely clogged catalytic converter restricting exhaust flow is another possible cause. Recommended troubleshooting steps: First read fault codes, then measure cylinder compression, finally check fuel injection pulse width and ignition waveforms.
