Car Engine Sputtering – Causes & How to fix it

Driving should be smooth.

But, if you are driving and your car’s engine starts sputtering the first cause of concern would be low fuel.

However, if your fuel gauge is full it could be a symptom of further engine problems. A blocked fuel injector can prevent fuel from reaching the combustion chambers.

If the problem is not corrected immediately, it can lead to further engine damage.

Causes for engine splutter

There are a lot of different reasons which could cause a sputtering engine, here are a few of the most common symptoms.

1. Faulty spark plugs

Spark plugs are vital to providing the necessary ignition for the air/fuel mixture. However, plugs wear out and can no longer function as intended. In this case, you will have lots of unburnt fuel with causes misfires and the engine to sputter. During your next service time ensure that you have your plugs replaced. Faulty spark plugs will cause misfires, which can be identified as sputtering.

2. Dirty fuel injectors

The fuel injectors play the role of spraying fuel into the combustion chambers. This is then mixed with air and ignited by the spark plugs. When the fuel filter is dirty then you have less fuel going to the combustion chambers. This will cause your car to experience slow acceleration. You can clean your fuel injectors and the problem may be solved.

3. Vacuum leak

The car has a set of vacuum hoses that with time develop leaks. This will cause the engine to produce a sputtering sound when the air-fuel mixture gets too rich or too lean.

4. Dirty mass airflow sensor

The combustion chamber requires the right amount of fuel and air. Modern engines have an onboard computer that monitors the flow of these components. The mass airflow sensors ensure that the right amount of air is supplied to the combustion chambers.

When the sensors get saturated with dirt particles they can no longer relay the right information to the ECU. This will cause more or less air going to the combustion chambers. You can solve this problem by having them cleaned.

5. Exhaust system leaks

The internal combustion engine works through the ignition of fuel and air mixture. Exhaust gases are produced as byproducts and this flow through the manifold and then to the atmosphere. The catalytic converter is vital for removing harmful compounds from the exhaust like hydrogen monoxide and carbon monoxide.

These gases are then converted to less harmful inert gases. When there is a leak in the exhaust system then these gases will start escaping before they reach the tailpipe. You will hear a sputtering sound. The situation can worsen as the exhaust gases are very hot and will melt some of the car’s components.

6. Faulty catalytic converter

The catalytic converter plays a vital role in removing harmful gases from the exhaust. When the catalytic converter is faulty some of these gases will find its way to the tailpipe. Sulfur needs to be broken down as it is harmful to the environment.

When your catalytic converter is not working well you will notice a strong smell of rotten eggs. With time the catalytic converter becomes broken the car will at some point stop working.

7. Dirty oxygen sensors

Most of the modern cars have an onboard computer that monitors all the engine components. Connected to this are oxygen sensors that are responsible for the regulation of fuel into the combustion chambers. A Faulty Oxygen sensor will cause a rich or lean mixture.

With time the oxygen sensors become contaminated with dirt and they no longer are able to relay the correct information to the onboard computer. This causes them to release too much fuel or little fuel. You should make every effort to replace the oxygen sensors occasionally.

8. Worn out seals/gaskets

The seals and gaskets prevent exhaust gases and oil from finding its way to the combustion chambers. When these fail you will start experiencing a sputtering engine. Further seal damage will eventually lead to the complete destruction of the exhaust manifold. The solution to this is to simply replace the seals and gasket if you find any leaks.

How to fix engine sputtering

The engine sputter can be caused by a variety of factors and you will need to carefully examine each component to identify that which is not working. Some of the parts you need to replace include the spark plugs, wires, rotor or the distributor cap.

The sensors like MAF/MAP/O2/ECT sensors will need to be cleaned so that they transmit the correct readings to the ECU. You will know it is time to replace your spark plugs if they appear burnt or the wire insulation is worn out. The distributor cap and rotors should be free from any cracks. You should also clean them off any carbon deposits.

Ignition coil

Next check the ignition coil. You can use an ohmmeter to check that it is passing the right voltage. If the coil is faulty replace it with the manufacturers recommended coil.

Fuel Injectors

The fuel injectors are vital for supplying fuel to the combustion chambers.

You can check whether they are in good working condition by using a stethoscope. Turn on the engine and as it idles place your stethoscope on the fuel injectors. You should hear the valves open and close. If this does not happen then you have faulty fuel injectors that need replacement.

Vacuum Hoses

Vacuum hoses have a high likelihood of developing leaks. The high engine temperatures can cause cracks to the vacuum hoses hence hindering engine performance. You will need the help of your local mechanic to replace the vacuum hoses.

Filters

During your next service time, ensure that you replace the fuel and air filters. These often get clogged with dirt with continued usage. In addition, you may need to check your fuel spray pattern. To do this dismantle the air assembly, and remove the air intake. A well-functioning air intake should have an even spray pattern. If it is uneven then you will need to replace it.

Conclusion

A spluttering engine is a cause of concern for many motorists. It could mean that your fuel injectors are clogged and are no longer supplying the right amount of fuel. If the catalytic converter is faulty harmful gases can find their way to the atmosphere.

Some of these gases are like sulfur are identified by their strong egg smell. Having your mechanic examine the vacuum hoses can identify the source of the leaks. You will also be required to replace air filters and clean the oxygen sensors.

Magnus Sellén

Hello I'm Magnus, the owner and the writer of this website. I have been working with cars since I was 16 and I'm specialized with in-depth Automotive diagnostics. Also been driving drifting for the last 6 years. I'm here to give you answers to all your automotive questions and I hope that you enjoy our content.