Whenever you sit with your car on, your engine should be smooth and calm for the most part. But a rough idle can be pretty startling with its unusual sounds. There are various factors that can come into play to explain why you may experience rough idling. Regardless of the cause, you’ll want to address the problem and repair it ASAP to avoid further engine damage.


Common Causes Of Rough Idling

Old Spark Plugs

Spark plugs are small metal pieces in charge of igniting the air and fuel mixture within your combustion chamber. Oil and carbon deposits can build upon and around your spark plugs over time. The debris can ultimately lower the power to start your car. To fix this problem, simply replace your spark plugs!

Vacuum Leak

There are numerous hoses placed around the engine, and they are there to form a vacuum seal controlled by the throttle to manage airflow and engine speed. However, the hot engine temperatures can sometimes wear out the hoses resulting in air leaks. If too much air is added to the air and fuel mixture, then your engine will be rough idling.

Clogged Fuel Injector

A dirty fuel injector can also cause rough idling. The fuel injector administers the correct amount of fuel into the engine’s cylinder at the appropriate time for a smooth function. The fuel injector is also prone to carbon build-ups, which can eventually clog the nozzles.

Carburetor Issues

This isn’t a problem in newer model vehicles but can happen in older cars. Older vehicles use a carburetor rather than a fuel injector system. If you see a dark or black exhaust smoke accompanying the rough idling, you are likely dealing with a carburetor problem.


As you can see, there is more than one potential reason why your BMW is idling rough. The causes range from simple to complex fixes, which is why it is best to have the problem uncovered by a certified professional. If you need engine repairs, we invite you to bring your BMW (or MINI) to Motorhaus today!


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