Hello today we will be going over why the car idles rough but drives smooth.

On most newer cars are relatively quiet and ride nice the new stuff and functions work very well. Now a bit into the future this car got nosier and having a rougher ride.

There is a lot of things that may go wrong causing you to get a little creative.

Just because the car is getting older doesn’t mean that you are going to need a new car. A little bit of TLC will go a long way to get your car back into the action.

Older cars may experience rough idling or vibrations that can be eradicated just by simple maintenance.

Why Does My Car Idle Rough?

A engine needs the correct air and fuel ratios to obtain the smoothest combustion process.A well functioning engine that is receiving the optimal mixture of air and fuel is to be able to make a smoother ride as well as.

Generating the power that is required to operate critical systems such as the power steering,air conditioning, electrical system, and the cooling system.

A vehicle that is idling rough produces a sluggish feeling and strange vibrations. The reason is more than likely a failed system in the engine and it needs attention before the engine quits.

Also the poor fuel efficiency and poor performance, trouble starting, high RPM’s/low RPM’s, bad idling may be precursor to demanding engine problems in the future.

Vibrations and rough idling should be taken as a warning sign to get the vehicle to a repair shop. Before the costly repairs come in driving it like that.

Worn Out Spark Plugs

Combustion needs fuel,air and the spark. The spark plug and wires and ignition coils help produce the voltage to ignite the system.

The air/fuel mixture in each of the cylinders. Overtime, spark plugs collect oil and carbon deposits that lessen the performance created during the ignition.

Replace spark plugs every 30k-50k miles for the best performance possible and to prevent damage.

Vacuum Leaks

In the engine bay there are many hoses that slither around the engine . The hoses are meant to create a vacuum seal for the air and fuel controlled by the throttle to regulate air flow.

This also controls engine speed and the vacuum within the intake manifold. After a couple of years go by the exposure to extreme temperatures cause damage.

The rubber in hoses wear down and develop leaks. If to much air is added to the air/fuel ratio it can cause the misfires and rough idle.

Have a certified automotive technician inspect these every 50k miles. For cracks,breaks, or dryness.

Clogged Fuel Injectors

A car that is idling rough but drives smoothly may be because of broken motor mounts. The motor mounts help hold the engine when the RPM’s increase.

These mounts are what keep it in place. Broken or weak mounts are unable to support the engine properly, making the vibrations at idle.

Though there’s no schedule to getting them replaced, the average life of a motor mounts life is around 5-10 years. Get them inspected every so often.

What To Do If Your Car Is Idling Rough

As you drive the vehicle is taking air through the intake into the engine. However to prevent dirt, debris and other contaminated stuff from damaging delicate components.

The engine is equipped with an air filter. The air filter slowly becomes clogged and may do more harm than good because the proper ratio of air is not going into the engine.

If the incorrect of air is not going through the engine this can cause rough idling and poor fuel economy. Air filters need to be replaced every 15k miles.

If the car is struggling to idle or poorly start. Replace the air filter. If this doesn’t fix it visit a auto shop to get it checked out.

Rough or bad idling is not something a car should do. Routine maintenance will help in the case of preventing major damage to the engine.

This can help sure the parts are operating correctly. If an older car starts vibrating and maintenance has been maintained go to an auto shop immediately.


Always be up on the maintenance on a vehicle shaking is not good. Car idling rough but runs smooth. This is a very scary problem that will need to be checked out as soon as possible, Thanks for reading

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