What Causes a Car Engine to Sputter?

A sputtering engine usually means the power isn’t flowing smoothly. The issue might even be linked to the transmission. Here’s the scoop: the internal combustion engine mixes air and fuel, ignited by the spark plug, creating an explosion that pushes the piston down. This motion turns into circular force, which then powers the wheels through the transmission.

When something goes wrong in this system, sputtering can happen. Most often, the trouble comes from fuel, air, or sensor issues. Here’s a quick rundown of the usual suspects:

• Fuel pump
• Fuel filter
• Fuel injector
• Spark plug
• Throttle body (dirt can block airflow at idle)
• Mass Air Flow (MAF) sensor
• Vacuum leak
• Catalytic converter blockage or oxygen sensor failure
• EGR valve clogged

Chances are, if one of these components is acting up, it’s only partially failing—sometimes working fine, other times not. That’s what leads to that frustrating sputtering sensation.

Car Engine Sputters While Driving and Idling

If the car sputters both while cruising and idling, the fuel system or MAF sensor is likely to blame. The sputtering feels like a sudden power drop, making the car lurch. This is usually tied to the fuel system since it can’t handle big changes smoothly.

Check these components:

• Throttle body and plate
• Throttle Position Sensor (TPS)
• MAF sensor

The fuel system has several points where gas flow can get interrupted—like the pump, lines, filter, and injectors. If there’s a blockage or pressure drop, some cylinders might get too much fuel while others get none, leading to misfires. It’s best to have a mechanic inspect the whole system.

The MAF sensor tells the engine control unit (ECU) how much air is coming in so it can adjust the fuel accordingly. If the readings are off, it’ll mess with the fuel mixture, causing that sputtering feeling. In rare cases, the issue could be with the ECU itself, so an automotive electrical expert might need to take a look.

Car Idles Fine But Sputters When Accelerating

If the car idles smoothly but sputters when the gas pedal is pressed, the throttle position sensor (TPS) could be the issue. The TPS might be dirty or damaged, causing inconsistent readings that mess with fuel delivery when accelerating.

Also, check the transmission fluid and the Transmission Control Module (TCM). Like the TPS, the transmission doesn’t kick in until the car starts moving, so issues here might only show up during acceleration.

After checking the TPS, it’s smart to look over the fuel system for any misfires, like spark plugs and ignition coils. Some problems might only rear their heads when accelerating but could still affect idling.

Car Sputters When Starting and Idling

If the car sputters while idling, it’s likely struggling to maintain a steady speed, almost stalling. The idle air control actuator, fuel system, or a general misfire could be the culprits. A dirty or damaged MAF sensor or a clogged EGR valve could also cause issues.

A quick clean of the throttle body might help, but if the problem persists, a technician should take a closer look. They’ll figure out what’s wrong and give a rundown of necessary repairs, which might include:

• Spark plugs
• Ignition coils
• EGR valve cleaning
• Fuel filter or pump
• MAF sensor

Car Sputters When Starting

If the car sputters when starting but smooths out afterward, the starting system might be the issue. When the key is turned, the battery powers the starter motor, which gets the engine going. Most misfires happen during starting or running, but starting issues can be linked to:

• The starter motor
• A rich fuel mixture for starting

Check the battery first. If that’s not it, inspect the starter motor and the rest of the starting system. Also, keep an eye out for other misfire signs that might be less noticeable when the engine is running.