Why does the Chery QQ 3-cylinder engine shake?
3 Answers
Chery QQ's 3-cylinder engine shakes due to low cylinder pressure. Methods to solve low cylinder pressure: Clean or replace the air filter element in time. Adjust or replace piston rings. Replace cylinder liners and cylinder gaskets. Adjust or replace valve springs. Replace sealing rings. Overhaul or replace valves and valve seats. Adjust valve clearance. Causes of insufficient cylinder pressure: Air leakage in the engine crankcase; Wear between engine piston rings and cylinders; Piston calipers getting stuck in the engine; Air leakage between the engine cylinder head and cylinder; Air leakage between the engine spark plug gasket and cylinder head; Air leakage in the engine pressure relief valve.
I've been driving a Chery QQ for three or four years, and the vibration issue with the three-cylinder engine is indeed quite annoying. The main reason is that three-cylinder engines are inherently unbalanced in design. With only three cylinders, the ignition intervals are uneven, creating a shaking force with each ignition, unlike the smooth operation of a four-cylinder engine. The Chery QQ uses a three-cylinder engine to reduce costs and improve fuel efficiency, but the resulting vibration is noticeable, especially at idle when sitting in the car—the steering wheel and seats vibrate. Over time, if the engine mounts age or the ignition system develops minor issues, such as carbon buildup on the spark plugs causing uneven ignition, the vibration becomes even worse. To mitigate this, regular maintenance is key—checking for cracks in the rubber mounts and ensuring timely oil and spark plug replacements. Overall, this is a common drawback of three-cylinder engines, trading some comfort for affordability.
I've worked on quite a few Chery QQ models and found that three-cylinder engine vibration is usually caused by multiple factors. The primary issue is inherent mechanical design flaws: the firing order of three cylinders creates intermittent vibrations in the system, which are easily felt when transmitted to the car body. Then there's wear and tear - when engine mounts age, their shock absorption deteriorates, and poor ignition wire contact or faulty spark plugs can worsen vibrations, such as noticeable body sway during acceleration from standstill. Additionally, delayed maintenance by some owners, like clogged air filters or unstable fuel pump pressure, can also make engine operation uneven. For solutions, I recommend first checking mounts and ignition systems, using tools to measure data, and maintaining regular servicing to prevent worsening. Three-cylinder engines are simply more sensitive than four-cylinder ones and require closer attention.
