A healthy engine runs smoothly. When it starts to shake at idle, stumble when you accelerate or feel rough at traffic lights, something in the combustion process is not working as it should.
The cause is usually one of three things: the spark, the fuel or the air. Here is how to think about it.
Ignition problems
Each cylinder needs a strong spark at exactly the right moment. When that fails, the cylinder misfires and the engine shakes.
- Worn spark plugs
- Failing ignition coils or leads
- A weak battery or charging issue affecting the electronics
Fuel problems
- Clogged fuel injectors
- A weak fuel pump or blocked fuel filter
- Poor quality fuel or water in the fuel
Air and sensor problems
- A dirty air filter or throttle body
- A vacuum leak or cracked intake hose
- Faulty sensors such as the mass airflow or oxygen sensor
- Worn engine mounts, which let normal vibration reach the cabin
Clues that help narrow it down
- Shaking only at idle often points to ignition, vacuum leaks or mounts
- Shaking under acceleration often points to ignition or fuel delivery
- A flashing check engine light means an active misfire: reduce speed and avoid hard driving
- Rough running with a fuel smell or black smoke suggests a rich mixture
What to do
A diagnostic scan reads the stored fault codes and shows which cylinder is misfiring, which saves guesswork. The workshop can then test the plugs, coils and injectors and check the intake for leaks.
If your car is shaking or running rough, call or WhatsApp us and describe when it happens, and we will advise what to check and when to bring it in.