Engine Sputtering: Reasons And How To Fix It

A sputtering engine during acceleration or when the vehicle is stopped is very disturbing. Learn the most common causes of engine sputtering.

Engine Sputtering during acceleration

Experiencing engine sputtering while driving can be quite concerning. Engine sputtering indicates an uneven and unusual noise and performance of an engine, often characterized by poor engine performance and a rough running condition.

If your vehicle stutters or hesitates, particularly at lower RPMs, it might indicate problems related to the air filter or potentially issues with components such as the fuel pump, fuel injector, or fuel filter. This article explains why your engine sputters during acceleration and how to fix it.

Reasons Why Car Engine Is Sputtering

The engine of a car usually sputters due to a faulty spark plug, a bad MAF sensor, a bad fuel pump, or a clogged fuel filter. It may also be caused due to a clogged fuel injector, a vacuum leak, a bad O2 sensor, a faulty catalytic converter, or an exhaust leak.

Let’s discuss the reasons for engine sputtering in detail:

1) Faulty Spark Plugs

A faulty spark plug is one of the major causes of engine sputtering during acceleration. The spark plug is used to initiate the ignition process of the air-fuel mixture.  

Faulty Spark Plug, why a car engine sputters

When the spark plug becomes faulty, you need to replace it instantly.

The service life of a spark plug varies by plug type, with some requiring replacement after only 30,000 miles. Yet, iridium and platinum spark plugs have a longevity of up to 100,000 miles.

Regardless, the accumulation of carbon deposits may also lead to plug failure, resulting in engine sputtering. Hence, the initial focus should center on inspecting and addressing issues related to the spark plugs. Neglecting this could escalate to engine misfires.

Read More: Bad Spark Plug Symptoms and Causes

2) Faulty Fuel Pump

The fuel pump is not something you change regularly, but it may stop working over time. The purpose of the fuel pump is to transfer fuel from the fuel tank to the combustion chamber. If it has an issue, the engine won’t get enough fuel to run.

Bad Fuel Pump

Your car’s fuel pump may become faulty if you often let the fuel level in the tank become very low, which can make it draw dirt from the base of the tank. It may also stop working just because of its age or normal wear and tear.

Read More: Bad Fuel Pump Symptoms and Causes

3) Bad MAF Sensor

The MAF sensor, also known as the mass airflow sensor, has the important task of keeping track of all the air entering the engine, making sure that the engine’s engine cylinder gets enough air. This plays a vital role to make sure the right mix of air and fuel is in the engine.

MAF Sensor, mass air flow sensor

But, when the MAF sensor doesn’t send the right information to the powertrain control module (ECM), your engine might end up with the wrong air-fuel mix. If this means less fuel is being used, the engine doesn’t get enough and starts sputtering.

4) Vacuum Leaks

Your engine works like a pump that needs air. Your vehicle has a special create system of different hoses and parts that help the engine run smoothly by keeping the right amount of air.

Vacuum Leaks, causes of Engine Sputtering

When something goes bad with the vacuum system, it may lead to a vacuum leak. This vacuum leak badly affects the engine performance.

This leak can cause too much air to get mixed with the fuel, disrupting the air/fuel mixture and culminating in an inadequate fuel supply. The end consequence is once again fuel starvation, leading to sputtering.

Read More: Why Your Car Starts Then Dies?

5) Clogged Fuel Filter

A clogged fuel filter is another potential cause of engine sputtering. The fuel filter of your vehicle ensures proper and contaminated-free delivery to the engine. The filter accumulates contaminants, dirt, and debris, effectively preventing these particles from entering the engine.

Fuel Filter

Over time, this filter gets clogged due to the contaminants. However, as it clogs, fuel flow to the engine gets obstructed, inducing sputtering. The engine might exhibit signs of fuel deficiency, even if your fuel gauge indicates a full tank.

Read More: Bad Fuel Filter Symptoms and Causes

6) Clogged Fuel Injectors

A fuel injector is one of the most really important parts of your vehicle’s fuel system. Its function is to inject a specific amount of fuel into the combustion chamber. How much fuel gets sprayed is decided by sensors and the PCM.

damaged fuel injector

When these injectors get blocked, they can’t inject fuel efficiently as they should. This leads to sputtering because the engine isn’t getting the right amount of fuel it needs to run smoothly.

Read More: Clogged Fuel Injector Symptoms and Causes

7) Out of Gas

One of the major reasons for engine sputtering is running low on gas. As the engine receives less fuel, it struggles, and eventually, your vehicle might stall.

When your engine sputters, the first step is to check your fuel gauge. If the gauge indicates sufficient fuel in the tank, running out of fuel might not be the issue (if the gauge itself is not defective).

8) Bad Oxygen Sensors

A bad oxygen sensor almost produces similar issues as a bad catalytic converter. The oxygen sensor is responsible for monitoring the amount of air in the exhaust. When it becomes bad, it may send the wrong information to the PCM.

bad Oxygen sensor

If it gives incorrect information to the PCM, the air-fuel mixture in the engine cylinder can be disturbed.

This might lead to introducing more air, resulting in insufficient fuel. Without the right amount of fuel, the engine sputters, much like it would if the car is running low on fuel.

9) Faulty Catalytic Converter

The catalytic converter of a vehicle plays a crucial role in the emission system. However, it’s prone to becoming blocked with time, especially when the air/fuel mixture is not mixed correctly.

Catalytic Converter, reasons of engine sputtering

As you know, the exhaust gases of the engine require an open pathway to exit through the exhaust pipe; a blocked converter can cause a backup.

When the exhaust gases won’t be expelled, they affect the performance of the engine. You might observe sputtering and a reduction in engine power until you resolve the blockage.

Read More: Bad Catalytic Converter Symptoms and Causes

10) Exhaust Manifold Leak

An exhaust manifold leak can also lead to uneven running or sputtering of the car’s engine. This might trigger the check engine light and cause increased engine noise.

A leaking or cracked exhaust manifold is a safety concern. The leakage of the exhaust gases may damage plastic components, and exhaust fumes might enter the cabin. It’s crucial to address this promptly to avoid hazards, and it’s recommended to get it repaired as soon as possible.

11) Bad Throttle Position Sensor

The throttle position sensor is one of the most important engine sensors. The powertrain control module (PCM) utilizes the data of this sensor to adjust the ignition timing and fuel injection rate.

Symptoms of Bad Throttle Position Sensor

When the TPS malfunctions, it may send the wrong information to the powertrain control module (PCM) of your vehicle. Due to the wrong information from the throttle position sensor, the PCM might inject the wrong amount of fuel, leading to the wrong air-fuel mixture. This can result in rough idling, sputtering, and even engine misfires.

Read More: Bad Throttle Position Sensor Symptoms and Causes

How To Fix A Sputtering Car Engine

To fix a sputtering engine, you need to repair or replace one of the following parts:

1) Read Trouble Codes

The initial action to diagnose car issues is to retrieve the Diagnostic Trouble Codes (DTCs). When the Check Engine Light is illuminated, it indicates that a code has been stored in the vehicle’s computer. Using a suitable scanner, you can interpret these codes.

OBD2 scan tool, scanning trouble codes

Interpreting the codes might not always be straightforward, so we provide a trouble code library for your assistance. If you’re confronted with numerous codes, you can reset them and take a short drive. This reset process will clear the latest codes, simplifying the process of identifying the current problem.

2) Fix Vacuum Leaks

Properly inspect the vacuum system for a leak. If there is any leak, fix it immediately. Follow the below-given steps to fix the vacuum leaks:

  • Commence by locating the vacuum system connections and vacuum lines. Consult with your vehicle’s owner manual to easily find the vacuum lines.
  • Conduct a visual examination of the connections and lines to identify evident problems. If you notice disconnections or cracks, swift replacement is feasible.
  • Utilize a propane torch along the lines without igniting it. An increase in idle indicates the presence of a leak.

An alternative method involves utilizing carb cleaner to detect leaks. Follow the above-given steps for the propane torch test. However, exercise caution not to spray any surfaces that could potentially ignite the propane torch or cleaner.

3) Check Fuel Pressure

Test the fuel pressure in the system by using a fuel pressure tester. Consult your vehicle’s service manual to check the sufficient fuel pressure for your vehicle, as it varies according to the model.

Fuel Pressure Inspection

For instance, the conventional throttle-body system might be adequate with just 10 psi, whereas multi-port injection systems could demand around 60 psi. Even identical vehicle models from various years might exhibit variations.

When encountering fuel pressure issues, it’s essential to pinpoint the root cause. Perhaps only the bad pump needs replacement, or a new filter might be necessary. Alternatively, using an additive to clean the fuel injector could potentially resolve the problem and have you back on the road.

4) Check Spark Plugs

Properly inspect the spark plugs for each cylinder. If any of these spark plugs are damaged, replace them as soon as possible. Follow the below-given steps to inspect the spark plug:

  • Take out the spark plugs and visually examine them. If there is no damage, it means that there’s no issue with the plug.
  • If you notice damage to the plug, you need to replace it.
  • If carbon is accumulated on the spark plugs, cleaning might be possible. Utilize a wire brush and a spark plug spray cleaner to clean the spark plug.
  • Employ a spark plug tester to assess whether replacement is necessary.

When opting for new spark plugs, you might consider upgrading to platinum or iridium options, known for their extended lifespan.

5) Check The Throttle Position Sensor

Properly inspect the throttle position sensor for damage. If the sensor is damaged, replace it immediately. If the sensor is clogged, you need to clean it properly.

6) MAF Sensor Cleaning

MAF Sensor Cleaning, how to fix engine sputtering

As discussed above, a bad or clogged MAF sensor is one of the major causes of engine sputtering. If your MAF sensor is clogged, follow the below-given steps to clean it:

  • Switch off the engine and let it cool down. Wait for about 15 to 20 minutes to properly cool down the engine
  • Disconnect the sensor.
  • Gently remove the sensor from the brackets, securing it.
  • Clean the sensor using a product designed for MAF sensors.
  • Allow the sensor to dry thoroughly.
  • Reattach and secure it by tightening the brackets.

Read More: How To Clean A MAF Sensor

7) Consult To A Mechanic

If you find yourself unable to identify the issue or are uncertain about how to fix the problem, it’s advisable to seek assistance from a mechanic. When your engine sputters, it’s important to address the issue promptly and correctly.

FAQ Section

Why my car sputters when accelerating at low RPM?

Experiencing hesitations or sputtering at low RPM in your car could indicate potential problems with the engine’s fuel pump, fuel injectors, fuel filter, or air filter.

Why does my car idle fine but sputters when accelerating?

When your car engine sputters during acceleration but runs smoothly at idle, it might be because of exhaust system problems. A damaged or clogged exhaust system creates backpressure, affecting engine power and causing sputtering during acceleration. Issues with components like the exhaust pipes, muffler, or catalytic converter may lead to this problem.

Why is my car sluggish at low RPM?

Sluggish acceleration at low RPM can result from various factors, such as an issue with the fuel filter, low fuel pressure, or air intake complications. A dirty or malfunctioning MAF sensor can also contribute to reduced speed. Furthermore, an imbalanced air-fuel mixture, either too lean or too rich, might be at play.

Does the fuel pump affect RPM?

Yes, when the fuel pump of your vehicle delivers excessive fuel to the combustion chamber, you might notice unusual spikes in RPM and acceleration. Conversely, insufficient fuel supply can lead to engine stalling.

Why my car sputters when starting after sitting?

Your vehicle’s fuel system contains a mass airflow sensor, an oxygen sensor, and a fuel injection sensor. When any of these parts become faulty, your vehicle will not receive the correct air-fuel mixture upon starting, resulting in sputtering.

Why is my car sputtering and the check engine light comes on?

An exhaust manifold leak may lead to uneven running or sputtering in your car’s performance. This issue might also trigger the illumination of the check engine light. Additionally, you might notice heightened engine noise accompanying the vehicle’s poor performance.

Is the engine sputtering bad?

That is not always the case. Sputtering is an indication that your engine isn’t receiving sufficient fuel. While simple fixes are possible in some instances and won’t demand much time, the problem could also be more severe. Hence, seeking a professional diagnosis becomes vital to prevent further complications.

Can low oil cause sputtering?

Usually, a low engine oil level won’t produce the same kind of sputtering sensation associated with fuel shortage. But insufficient lubrication may cause misfiring.

How do I know if my engine is sputtering?

Sputtering engines may produce different drivability issues. Initially, it might seem like hesitation or a lack of power, particularly during driving. In more critical scenarios, the engine sputtering may escalate into backfiring or misfiring, which is a more severe issue.

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