Car hesitating when accelerating.

When accelerating from a stop, the car hesitates even with the gas pedal to the floor. Eventually, it runs fine, but does this every time I accelerate from a slow to fast speed. No warning lights are coming on.
Experienced mechanics share their insights in answering this question :
There are many sensors on a car that the computer relies to tell it what is happening. Things like engine temperature, air density, elevation above sea level, ambient temperature, etc., are all readings that your cars computer uses to determine how much fuel to inject at specific times.
A faulty sensor that is sending the wrong information will cause things to go out of balance. This can translate into a hesitation, a stumble, bad gas mileage, loss of power, etc.
Even though there is no warning lights, the cars computer can still have what are known as "soft" or "pending codes" stored. These are codes that do not turn on a light but are still stored in memory. Also Freeze Frame data records may be stored in the computers memory as well. These Freeze Frames are recordings that your cars computer takes of what is happening when your vehicle is acting up. They contain vital information that a technician can use to help diagnose the issue. A technician should be able to scan, extract, and interpret that information for a proper diagnosis.

How to Identify and Fix Common car Problems ?

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Common Reasons for Hesitation While Accelerating

Fuel Injectors: When the fuel injectors become worn out or dirty over time, this can prevent them from spraying fuel into the internal combustion chamber. When this doesn`t happen, engine hesitation will develop more and more over time.

Culprits include a dirty fuel filter, clogged fuel tank strainer, clogged or failing fuel injectors, or a defective fuel pump. On most vehicles replacing the fuel filter is a DIY operation.
An engine that is hesitating to accelerate is most likely dealing with a fuel/air mixture that is too lean. Engine`s that are running inefficiently will begin to show signs like hesitation which will only become worse over time.
When you press down the accelerator pedal and get minimal output, it could mean you have a problem with your fuel system. The most probable issue is a clogged fuel filter. Your fuel filter works to ensure that dirt and debris do not get into the fuel system.
If you press or let up on the pedal, there will be a delay before the engine responds. This is because of the time it takes the throttle motor to activate the throttle opening. Throttle response should be nearly immediate and not delayed. Gas pedal delay is a safety defect because it can cause accidents in emergencies.
Fuel injectors may become dirty over time and not be able to provide as much fuel to the cylinder as is needed. Dirty fuel injectors may cause the engine to run lean which will in turn, cause hesitation when accelerating. To resolve the issue, please request a diagnostic for poor or rough acceleration.
Rough starts, hesitation and poor acceleration are all common symptoms of a bad spark plug. If a spark plug or multiple spark plugs are faulty, they will have trouble creating the spark that causes the ignition process in your vehicle.
Yes. While the damage may seem small initially, the longer you drive with a bad oxygen sensor, the worse the damage will become. Eventually, you may experience rough idling, poor acceleration, engine misfires, an illuminated check engine light, and failed emission tests.
Dirty Air Filters

If not enough air can travel through the air filter, there may be too much fuel and too little air, or you could find that some dirt or debris may escape the filter and make its way into the engine. This, in turn, will cause jerking and juddering while driving and affect the overall performance.

One of the most common causes of a sputtering engine is an issue with the vehicle`s fuel system—the filter, pump, and injectors. These three critical components work together to ensure fuel flows smoothly from the fuel tank to your engine`s fuel injectors, and then pumps into the engine evenly.
The Quick Fix:

Clean air filters and fuel injectors will reduce the strain on your car. An engaged emergency brake causes the brake to drag slowing down your car. Disengage the brake to solve this issue. Sometimes acceleration problems are just because of low fuel or poor quality of fuel.

An excessively lean or rich fuel/air mixture is most likely the cause of a lag when accelerating. An engine operating inefficiently will exhibit symptoms like hesitancy, which will only worsen over time. Have your vehicle checked immediately were you to detect any signs of this.
If your car hesitates when accelerating at low speed, you likely have a lean air-to-fuel mixture—meaning the gas getting to your engine doesn`t have the correct mix of fuel and air.
If your car hesitates when you try to speed up at a low speed, it`s likely because the air and fuel ratio is too lean. A lean air-to-fuel ratio means the gas going into your engine doesn`t have the right amount of fuel and air.
Dirty fuel injectors are among the most common reasons for why an accelerator becomes jerky. The dirty injector leads to your car losing power when you attempt to accelerate while at a stop and when you try to drive at a consistent speed.
Malfunctioning spark plugs can result in increased fuel consumption and emissions because of incomplete combustion. The lack of proper acceleration is another sign of faulty spark plugs in a car. This causes the engine to not respond and struggle to increase speeds when the accelerator pedal is depressed.
New spark plugs can also help increase your car`s power and acceleration, making it easier to get up to speed (literally). In addition, new spark plugs can also help reduce emissions from your car`s engine.
Find the reset button on the left side of your instrument cluster. Press the reset button and hold it until your display shows “To reset: Press reset button for 3 seconds.” Push the reset button again and hold it in until the display shows the system has been reset.
An indication that a vehicle is not receiving the right mixture of air and fuel is if the vehicle jerks or surges forward at high speed. Several components of the fuel or air intake system could cause this jerking or surging sensation to happen. Issues within these systems can also cause fuel economy to worsen.
When the inner CV joint is damaged or begins to fail, you will notice your car vibrating under hard acceleration. As it gets worse, the minor vibrations turn to violent shaking when under load. Damaged CV joints usually occur because of a tear in the joint boot.
As you get into the higher speeds, if you distinctly feel vibrating coming from the engine, this could be a result of a lack of power, fuel, or oxygen getting to it. The spark plugs, fuel filter, and air filter should all be checked and replaced as needed.
A sputtering engine may just mean you need to have your fuel filter replaced. All vehicles have a series of vacuum hoses that create the fuel pressure. If one of them leaks or is damaged in any way, you will lose significant fuel pressure. The vehicle`s exhaust system can greatly impact the engine`s performance.
The engine RPM drop when changing gears is often caused by a failed throttle position sensor (TPS). When in use, the cone of the TPS accumulates soot that prevents the correct rod movement. If a TPS works abnormally, the air-fuel mixture will not meet the requirements.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

Rattling heard and felt from underneath car when accelerating. Car hesitates (as if it will cut off) when accelerating
ANSWER : Hi, thanks for writing in. Sorry to hear of your difficulty with your 2012 Sonic. The good news is your Check Engine Light is on, so what means the fault has been "recorded" by the engine computer and diagnostic codes will be available to the mechanic to search for the fault. The codes don’t necessarily indicate which "parts" have failed but rather will indicate which systems are malfunctioning and causing poor operation of the engine. Individual components in these systems will then have to be tested by the mechanic. The traction codes may or may not be related to the issue with the engine, the poor acceleration, but those traction codes will have to be evaluated as well. It is possible there is more than one problem. If you would like help, consider having an expert automotive technician from YourMechanic come to your home or office to inspect your vehicle for you and download codes your car computer has stored, and make or suggest any repairs as needed.

The car accelerates slowly, hesitates and shudders
ANSWER : Unmetered air can cause this type of hesitation and shuddering. Too much air compared to fuel will cause a lean misfiring condition. Fault codes need to be read out of your Mercedes C320’s engine computer to see if there are any underlying issues and those issues are corrected.

The induction should be inspected and checked for vacuum leaks. Also, fuel pressure and volume should be checked as well if the induction system checks out okay. A partially clogged fuel filter can cause a starvation issue on heavy acceleration. You may want to enlist the help of a mechanic, such as one from YourMechanic, who will have the tools and expertise to conduct this type of diagnosis and repair for your acceleration issue.

I put the wrong key in my car and a few weeks later my car just shut down and it will not start I believe it’s the computer but…
ANSWER : Hi there. What had happened is the wrong key set the security to the vehicle. This is to prevent the vehicle from starting with the wrong keys. Try removing the battery cables (+) and (-) for 13 minutes. During that time, put the original key in the ignition and turn it on. Activate everything in the car even though there is no power. Then remove the key and hook up the battery cables. The computer should have reset and reset the security. If the security is still being tripped, then I recommend seeking out a professional, such as one from Your Mechanic, to help you

i was driving and my oil light kept going off. Car had oil. Car wouldn’t accelerate. Car died. It does not turn engine over now.
ANSWER : It is very possible that the engine has been damaged beyond repair. Usually when the oil light goes on and the vehicle is low on oil, especially when a loud noise is heard right before the vehicle died, it is very likely that the engine is blown and would require replacement in order to continue driving the vehicle. I would recommend having the vehicle checked with a no start inspection. Consider YourMechanic as this service can be completed at your home or office.

Why is the car losing power and not accelerating? 1995 BMW 318is
ANSWER : Hello and thank you for contacting YourMechanic. Check the ground wire from the main engine to frame ground to the right side engine mount. If this wire is corroded or loose, this will cause the engine to loose power on acceleration. Also, check the throttle position sensor (TPS) for any damage or loose wire connections. If the wires are all in good condition on the engine and the TPS, then I recommend replacing the TPS. If you need further assistance troubleshooting your vehicle, then seek out a technician, such as one from YourMechanic, to diagnose the vehicle’s loss of power and proceed with any needed repairs.

Was going up a hill and the car started to hesitate to get acceleration and the muffler is shaking now when idle
ANSWER : This may be related to many different things that can cause the engine to struggle. One possibility may be a sign of a clogged catalytic converter. As you may already know, the catalytic converter converts toxic exhaust gases into less harmful pollutants that are suitable to be expelled into the atmosphere. When this is clogged, this causes these gases to be backed up into the exhaust system not allowing the engine to breathe properly (think of a backed up sink). When this happens, the engine is forced to work much harder to expel these gases. This often results in the engine bogging down, hesitating, shaking and causing very poor fuel economy. Typically when this happens it may also cause the catalytic converter to become very hot and in some cases turning bright red. This should also cause a check engine light to come on as the O2 sensors should be reading the incorrect amounts of oxygen in the exhaust gases if this is your problem. I would recommend having an expert from YourMechanic come to your location to diagnose and replace your catalytic converter.

My engine light is on, why does my car hesitate sometimes when trying to accelerate or after I brake?
ANSWER : Misfires can be caused by a number of things. Poor fuel quality can cause misfires across all cylinders and possibly clog fuel injectors. Also, worn spark plugs can cause misfires as can the ignition coils that supply the spark plugs with the electricity to fire properly. Any of these will cause loss of power and economy. The oxygen sensor can also be a cause of poor performance but usually will set a fault code if the sensor has gone bad. Typically, a bad catalytic converter is not the "cause" of performance issues but is usually the "effect" of misfires and poor engine performance. If the catalytic converter is bad, something else (like misfires) made it go bad. Replacing the converter without addressing what made it go bad is not the route to take.

Since the cost of randomly replacing components can run into the hundreds, if not thousands of dollars, have a certified technician look into why the check engine light is on to isolate the exact cause. It will save you time and money.

The car hesitates and jerks during quick acceleration
ANSWER : It sounds like you may be experiencing an issue with your fuel system. The fuel pressure regulator is one of the parts responsible for maintaining your fuel pressure at all rates of engine speed. Most fuel pressure regulators are controlled by engine vacuum. It is possible that your fuel pressure regulator has failed or the vacuum line that connects to it is leaking. I would consider the vacuum leak more likely considering that engines produce less, vacuumed at higher RPMs. I would recommend having your fuel pressure regulator as well as the rest of your fuel system inspected by a qualified technician. Ensure that this job is performed by a professional, such as one from YourMechanic as fuel can be very dangerous. If you are looking to solve this problem, I recommend a mechanic from YourMechanic to inspect and diagnose why your engine hesitates, during acceleration.