5 Reasons For Rough Idling

August 12, 2022

Dream car fantasies are only for the hot-blooded youth. It’s only when you grow old and wise that you begin to understand that a vehicle that never causes problems should be your dream car. Once you experience the satisfaction of driving a reliable daily driver, all the ideas of a flashy sportscar go down the drain.

But even a reliable vehicle needs regular maintenance, or else problems like rough idling can sprout from nowhere. You need to be careful and look at the symptoms. If you witness any major ones, then the best course of action is to book an appointment with the mechanic to get your car back in good shape.

It’s even better to avoid expensive repairs and diagnose the issue before it gets worse. Here are a few reasons why your car could be experiencing rough idling.

Faults in the Spark Plugs or Distributor

Spark plugs play an integral role in the combustion process of an engine. They create electrical sparks, which are necessary to ignite the air/fuel mixture and help the pistons to move. But these small components have a short lifespan, and they malfunction after around 60k miles.

The fault results in irregular and intermittent sparks. The whole combustion process gets disturbed, the pistons go haywire, and you experience rough idling. Fortunately, faulty spark plugs are easy to diagnose, and you can do that yourself.

All you have to do is listen to the sound of the engine. If it sounds smooth then there are no irregularities. However, if the motor skips a beat or misfires, then you must immediately change the spark plugs.

Alternatively, a faulty distributor can also present similar issues. The distributor is in charge of the firing order and if that messes up, your car misfires. So, make sure the distributor cap is snugly in its place. If it has malfunctioned, you should replace the old one with the new one.

Malfunctioning MAF sensor

MAF is short for Mass Airflow Sensor and it is responsible for measuring the amount of air entering the engine. The sensor helps the ECU determine the amount of air needed to match the fuel in the system. The result is a nicely purring engine.

But what happens when the MAF goes bad? Well, the ECU has problems measuring and calculating the A/F ratio. The engine misfires use up more fuel, or even worse, it stalls.

Thankfully, it is quite easy to fix a MAF problem. It is even doable at home and doesn’t require the help of a mechanic. The first step is to clean the sensor using an ethanol and water solution. That’s because sometimes dirt and dust stick onto the sensor and reduce its efficacy to do its job. You can clean the MAF sensor and get it to work again in a few minutes.

If the problem persists, you can buy a replacement, which is usually not that expensive.

Issues in the Fuel System

The air and fuel mixture must always be perfect, and it mostly is unless there is an issue. We have talked about one part of it, which is the air intake. The other end is the fuel delivery system, which transfers petrol from the tank straight to the combustion chamber. The fuel must reach the chamber at the right time and in precise amounts. Otherwise, the engine function can go haywire.

The fuel system consists of the fuel pump, the fuel filter, the fuel rail and fuel injectors. All of these components must work in tandem with each other for perfect combustion. It is possible that one of the parts fails and disrupts the whole process. You will feel that with rough idling as the engine isn’t getting enough fuel.

The fuel filter, pump, and injectors are easily replaceable but that must be done by a professional. The fuel injectors, for example, are good for 50k to 100k miles after which they should be replaced. The mechanic will do that for you but at a high cost.

The fuel filter and pump, on the other hand, are less expensive and do not require trained labour to replace. You can do that if you have a factory service manual to help you out. All in all, you will be set back a few hundred dollars but the treatment will prevent rough idling and bring back the smoothness you desire.

Clogged Filters

The filters in a car are there to protect the vital parts from any damage. In the case of rough idling, the air filter holds importance. The air gets sucked in by the engine through the intake but not before going through the filter.

The air filter ‘cleans’ the air by removing pollutants and harmful elements so that the engine doesn’t get clogged. When the 3000-5000 mile mark hits, the filter usually is too clogged to perform well and must be changed.

That’s when you can experience rough idling and misfiring. So, the best thing to do is replace the filter. It is not that expensive, and you don’t need a mechanic to do the job for you. You can buy the air filter online, but make sure you get the right one for your car.

Low-Quality Fuel

Low-quality fuel causes rough idling, knocking and misfiring because the fuel doesn’t match the engine’s standards. The recommended fuel is mentioned by the car’s manufacturer, and it is also in the car’s user manual. It’s a good habit to glance at the manual for information and then put the right fuel in your vehicle.

If the car needs 92 ron, you could be damaging the engine by using 87 ron. So be careful of the type of fuel you put in your vehicle.

Turbocharged vehicles are more prone to this issue, and they can develop rough idling problems with low-quality fuel. If everything we have mentioned above is in prime condition and your car is still rough idling, then try changing your fuel station.

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Editorial Staff

The editorial staff is car enthusiasts who are part of the Everything Cars team. They write and manage the blog.

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