Causes of Engine Shaking and Popping Noises
3 Answers
The reasons for abnormal noises during engine shaking include poor sealing of individual engine valves, excessively rich air-fuel mixture, leakage in high-voltage wires or spark plugs, etc. Poor sealing of individual engine valves: When there is poor sealing or burning of individual valves, severe air leakage due to poor valve sealing, insufficient valve clearance, carbon buildup between valve seats and valves, or disconnection of vacuum tubes in power-assisted vehicles, the engine will exhibit idle shaking, produce abnormal noises, and these sounds will disappear when the engine speed is increased, with operation becoming smoother. Excessively rich air-fuel mixture: If the engine's air-fuel mixture is too rich, issues such as cylinder misfire, communication between individual water jackets and cylinders, water ingress into intake valves, loose piston ring sealing, ring seizure, piston top separation, excessive intake valve clearance, broken valve springs, lost lock pieces, or detached adjustment screws may occur. The engine will produce rhythmic abnormal noises at various speeds, severe shaking, and difficulty in acceleration. Leakage in high-voltage wires or spark plugs: When there is leakage in the engine's high-voltage wires or spark plugs, problems such as overly soft distributor breaker contacts, loose contact rivets, loose fixed brackets, incorrect valve clearance, faulty capacitors, or poor wiring connections may arise. This can cause the engine to run well at low speeds but exhibit shaking and irregular noises at medium speeds.
I just fixed a car with this issue - the engine shakes and makes a sputtering sound as soon as it starts. Most of the time, it's a problem with the ignition system, like excessively worn spark plugs failing to ignite, or faulty ignition coils causing misfires in individual cylinders, resulting in increased engine vibration. Fuel supply issues are also common; clogged fuel injectors or a dirty fuel filter can lead to insufficient fuel delivery, causing incomplete combustion that sounds like sputtering. Intake vacuum leaks can also cause shaking due to an imbalanced air-fuel mixture. I've encountered broken engine mounts a few times, making the engine unstable and producing abnormal noises. My advice is to first check if the spark plugs are burnt out - replacing them is simple. If the noise persists, take it to a repair shop as soon as possible to read the codes with a diagnostic tool to avoid damaging more components and compromising safe driving. Don't delay too long; engine health affects overall vehicle performance and fuel economy.
My own car started having this issue last year. After starting, it shakes violently and makes a popping noise, making it feel very awkward to drive. Preliminary checks suggest it might be due to a dirty throttle body with carbon buildup causing blockage, leading to poor airflow; or dirty fuel injectors causing inaccurate fuel spray and uneven combustion. Components in the ignition system, such as aging high-voltage wires, could also be the culprit—if the spark plug gap is too wide and fails to ignite properly, it can cause shaking. Later, it was discovered that insufficient fuel pump pressure was the main issue, as the engine protests when fuel supply is interrupted. If the engine mount rubber pads are cracked, the vibration and noise become even more noticeable. It's recommended to first try cleaning the throttle body and fuel injectors—this is low-cost and easy to DIY. If that doesn’t work, replace the parts promptly to avoid more serious issues like cylinder damage or excessive exhaust emissions.
