Driving Along: An Automotive Blog

3 Common Causes Of Engine Surging And Hesitation

7 June 2023 by Ruben Watson

Surging and hesitation are common symptoms of numerous automotive ailments. While these problems are relatively common, they can still be frustrating. Under the right circumstances, sudden surging or engine hesitation can even be dangerous. While these drivability issues don't often point to a critically expensive problem, they aren't something you'll want to ignore for long.

But what's causing your surging and hesitation? There's no way to know without a thorough examination by a qualified auto mechanic, but it may be due to one of these three relatively common problems.

1. Faulty Throttle Position Sensor

Despite the name, the throttle position sensor doesn't measure your foot's position on the gas pedal, at least not directly. When you press the gas pedal, a valve opens to allow air into your engine. The more air entering your engine, the more power you can get. However, the computer must also add the proper amount of fuel to maintain the correct air-to-fuel ratio.

The throttle position sensor (TPS) measures the opening of the throttle valve, allowing your car's computer to understand how much air is entering the engine. When the TPS fails, your fuel mixture may be drastically incorrect, leading to rough idling, stalling, hesitation, and surging. In most cases, a faulty TPS will also trigger your check engine light to appear.

2. Failing Mass Air Flow Sensor

The mass airflow (MAF) sensor is another critical part of your car's intake system. Nearly every decision your car's computer makes depends on knowing how much air enters your intake system. Since this air comes from the surrounding atmosphere, it's largely out of your car's control. Instead, the MAF sensor must read the data, report back, and allow the computer to make the appropriate decisions.

A faulty MAF sensor can have a potentially severe impact on drivability. Your computer will likely make extremely poor fuel mixture choices without knowing how much air is available. The result can be lean (too much air) or rich (too much fuel) conditions, as well as severe bucking, hesitation, and surging. The poor fuel mixture may trigger numerous diagnostic trouble codes and a check engine light.

3. Fuel Pump Problems

Many modern cars use high-pressure (or injector) and low-pressure (or lift) pumps. The lift pump's only job is to deliver fuel to the high-pressure pump, but it's still a common failure point. When your low-pressure fuel pump begins to fail, it may struggle to deliver sufficient or consistent fuel to the injector pump.

A bad fuel pump can create many problems, although it will eventually cause your car to stall or prevent your engine from starting. Before experiencing these issues, you may notice less severe symptoms, including hard-starting, loss of power, sudden bucking, and severe hesitation. Your fuel pump may not trigger a check engine light until the low fuel pressure causes other problems.

Reach out to an auto mechanic near you to learn more.

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