Why does my car hesitate while I accelerate? What are the most common reasons why a car experiences hesitation, shaking or misfire during acceleration ?…
Sometimes, your vehicle may stall during acceleration if it has a problem or misfires. This can cause the vehicle to stall, making it nearly impossible to use. The underlying cause could also damage other components and systems. You will need to determine the root cause of your car’s hesitance during acceleration and repair it as soon possible.
Why does the car hesitate during acceleration?
There is no one answer. It is important to do a complete diagnosis in order to determine the reason your vehicle slows down when it accelerates.
The reason your engine slows down during acceleration is usually one of the following.
Problems with the Ignition System
Your vehicle’s ignition system is responsible to ignite the necessary air-fuel mixture. It can cause misfires and stalls in your engine if the ignition system isn’t working correctly. The following are common problems:
- – Worn spark plugs
- – An errant ignition coil
- – Spark plug wires that are worn or damaged
- – Problem with distributor (if any).
- – If applicable, a defective ignition control module
Fuel Delivery Issues
Your vehicle’s engine needs a delicate air-fuel mixture to function properly. A lean engine can cause hesitation (insufficient fuel). The following are some of the most common reasons for fuel delivery problems:
- – Defective fuel injectors
- – Poor running fuel pump
- Fuel filter clogged
- – Defective fuel pressure regulator
Sensor Issues
Different sensors could cause the engine’s to run lean, misfire or have hesitation while accelerating. Examples include:
- Sensor for defective mass air flow (MAF).
- – Sensor to detect a defective throttle/accelerator pedal position sensor
- – Sensor for Defective Manifold Absolute Pressure (MAP)
Control Module Problems
The sensors located in the engine of your vehicle send information to a computer known as the powertrain control module (PCM). This information is then used by the PCM for checking the ignition coils, fuel injectors, and other components. The vehicle may hesitate when it detects a problem with the PCM.
PCM failure is rare, however. Older software is the most common reason why PCM fails to function properly.
Circuit Problems
All electronics (sensors and modules, etc.) that drive the motor are interconnected by circuits. Circuits connect all the electronics (modules, sensors, etc.) that drive the motor. These circuits can become faulty due to damaged wiring or loose connections, which can cause the vehicle’s to stop working.
Vacuum Leaks
The engine will deteriorate if unmetered or untreated air is allowed to enter it due to a leak. It could be anything, from a torn vacuum line to a faulty manifold seal.
Low Transmission Fluid Level
Low transmission fluid is the most common reason why an automatic transmission slips or disappears during acceleration. If this happens, you will notice that the vehicle is not as responsive to your pressing of the gas pedal. Transmission oil is needed to lubricate components and keep your vehicle properly running. Low transmission fluid levels can lead to transmission failure due to friction and overheating.
Other Engine Management Systems and Components Issues
Other engine management systems and components can also cause hesitation during acceleration. These are some of the most popular:
- Problems with the Variable Valve Timing (VVT) System
- – EGR system issues
- – Excessive exhaust pressure (usually caused due to a clogged catalyst)
- – Tightening issues
How to Solve the Problem of Engine Hesitation?
A vehicle may hesitate to accelerate due to many different issues. It is important to have a plan for troubleshooting. Most mechanics will start by reviewing the fault codes stored within the PCM. The codes may not tell you what happened, but they will give you an idea of where you should start. The short-term fuel trimming (STFT), is a key parameter to be examined when dealing with the problem caused by engine hesitation.
A STFT value of greater than 10% when the engine control system is in “closed loop mode” indicates that the engine has been running low. A STFT value below 10% indicates that the engine is running well. This information will allow you to narrow down possible causes for a hesitating engine.
Your success in troubleshooting depends on the information that you have gathered. To check for vacuum leaks, you may need to test the sensors using a digital multimeter or a fuel pressure gauge.
Also, don’t forget to do a visual inspection. Check for obvious problems such as damaged spark plug wires and broken vacuum lines. Repair any problems, remove all codes and test the vehicle again.
