A sticking gas pedal is not only scary, it’s very dangerous. When you get out on the road, you should be able to expect your car to do what it is supposed to do. When the gas pedal doesn’t respond properly, it’s time for repair. Read on to find out why your gas pedal has become sticky and what you can do about it.
Gas Pedal Sticking
Modern engines are designed whereas the engine control module calculates the air flow through the MAF. These signals should produce a normal air flow and fuel based on the gas pedal. The accelerator pedal sticking is called unintended acceleration. This problem can cause many other problems if it is not repaired.
Causes of Gas Pedal Sticking
The gas pedal should return smoothly when you press it to accelerate. If the pedal does not return, that means more fuel is being requested through the throttle. Of course, that is not good. A few things can cause the gas pedal to stick. Here are the most common reasons:
Mat blocking – Sometimes the problem is not so mechanical. The car mat may be blocking a part of the gas pedal travel. This problem can be solved by simply moving the car mat and see if your gas pedal is springing back.
Carbon buildup in butterfly valve in throttle body – The throttle body is the tubular unit found in the air intake between the d intake manifold and the air filter. The throttle is where the response comes from when you press your gas pedal. The gas pedal and throttle work together to supply the correct amount of the air/fuel mixture to the engine. That is why the gas pedal is one of the most critical parts of the throttle system.
The angle of the throttle plate regulates the flow of air into the combustion chamber. This plate is connected to the gas pedal. When you press the gas pedal, the plate rotates. The amount of air sent to the engine depends on how hard and long you press the gas pedal.
The butterfly valve in the throttle body moves rotationally. Opening quickly to regulate flow in the pipe. The valves are ideal for regulating large liquid or gas pressure flows. Carbon builds up in the butterfly valve which affects its performance. The valve will become stuck or struggle to move when it receives the commands. Over time, the dirty valve will cause the gas pedal to stick. To clean the butterfly valve, you must remove the throttle body and clean the valve. You can use throttle body cleaner and a soft cloth to do the cleaning. When the valve regains its shine, try the gas pedal to see if it solved the problem.
Damaged gas pedal assembly – Modern cars are equipped with an electronic assembly which includes the accelerator pedal position sensor (APP). The sensor is supposed to monitor the throttle pedal position and send signals to open the throttle body. This sensor tells the engine how fast to drive based on the driver pressing the gas pedal. The APP is designed to last for the lifetime of the car; however, this does not always happen. The sensor is located on the floorboard and heat can cause it fail. The cable may become frayed or dirty over time. This causes a lack of response when the gas pedal is depressed. Along with a sticky pedal, the warning light will activate on the dash, the cruise control won’t work, and OBD2 codes will be thrown.
Damaged throttle cable – The throttle body cable is connected to the spring loaded linkage on one end and the gas pedal on the other end. When the gas pedal is pressed, the throttle cable pulls the spring loaded linkage which is connected to the butterfly valve. There are sensors that monitor the changes in air and reports it to the engine control module (ECM).
The ECM then increases how much fuel is sent to the fuel injectors to maintain the correct air/fuel mixture. The computer depends on data signals from the manifold absolute pressure (MAP),sensor, MAF, and the Throttle Position Sensor (TPS). The information collected from these sensors are used to make sure the fuel-to-ratio measures remain constant and manageable.
Damaged throttle return spring – When the butterfly valve opens and closes, the throttle return spring closes the valve. The spring is attached to the throttle cable, the carburetor, or the throttle body. The spring may have just worn out with time o damaged due to heat or debris. Whether it is worn or damaged, the butterfly valve cannot properly close. The RPMs remain high after you take your foot off the gas pedal. The pedal may feel spongy as well as not returning to the normal position.
You Treat Your Car Like Badly – Most vehicle owners understand that a vehicle must be inspected and serviced from time to time, as referred to as routine maintenance. For those who don’t, the likelihood of problems that cause the gas pedal to stick is extremely high. If the vehicle is not inspected routinely, small problems can escalate to major problems that are much more expensive to fix. This is also true for vehicles which sit for long periods of time.
If you want to avoid throttle problems or other issues and save $100s of dollars that you’ll spend at the auto repair shop, you’ll need to service your vehicle often – you can use our mechanic-rated Auto Maintenance and Repair Manual to do this. It’s basically what mechanics use to go through your vehicle to check if there are any problems that need fixing. As soon as they notice the most minor problem, they’ll ask you to fork out some money even though it’s a problem you can fix yourself in minutes – the manual will teach you how to maintain your vehicle every few thousand miles and it’ll teach you how to fix minor problems that mechanics will ask you to pay for; saving you money in the long run.
A lot of our readers have the Auto Maintenance and Repair Manual printed on their garage wall and 92% of them haven’t visited the auto repair shop in the last year because they know what to do to avoid problems. All it takes is giving your vehicle a little attention every few thousand miles and you’ll never spend money at the workshop again.
Signs of Gas Pedal Problems
When the gas pedal is not working, it’s pretty hard not to notice. If you can drive at all with the sticky pedal, the ride will be full of surprises. There are a few signs that something is wrong with the gas pedal assembly that you can watch out for. Here are the most common signs of gas pedal assembly trouble:
Warning light on dash – The ECM will activate the appropriate light(s) on the dash to let you know something is wrong. The sensors will throw OBD2 codes if the gas pedal assembly, fuel system, throttle body, or throttle position sensor is not working properly. You can use an OBD2 Scanner (view on Amazon) to see if the codes have anything to do with the gas pedal assembly. You may also get the activated “Reduced Power” warning on the dash.
Stalling – The computer in your car expects reports of a specified amount of air flow through the throttle body. When that amount is not what is expected, the engine will stall, which means a delay when you try to start your car. The unresponsiveness is often called s a cold throttle. The timing of the signals and air flows are inaccurate. You may even also hear knocking in the engine for this same problem. The insufficient lean air/fuel mixture can occur because of several problems with the throttle position sensor, the oxygens sensors, fuel injectors or the mass airflow sensor. The air/fuel mixture is too heavy on air and light on fuel, which also causes multiple detonations in the engine.
Rough Idle – When you drive the car with irregular air flows, the handling will be irregular. When the car comes to a stop it will idle roughly. When you stop at a stop sign or traffic light, heavy vibrations will start which effect the engine power. You may also notice a loss of power when you try to accelerate. The car may stall when you press the throttle, which will cause the throttle body plate to open and close really fast.
Lower fuel economy – You won’t be able to go as far with same gas. Due to false high pressure readings from the sensors, the computer will interpret them as a signal for more fuel. As more fuel is pumped to the engine, it means less mileage per gallon of fuel for you. Over time, you will notice having to make more trips to the gas until the problem is solved.
Low performance – If there is a problem with your gas pedal assembly, the car will not run at peak performance. If the problem is not fixed, other parts will begin to malfunction. If the damage becomes severe, the engine may fail which means your car will not start up at all.
Lack of power – Your car will also exhibit poor power when you try to accelerate. The computer assumes that the intake manifold pressure is low and reduces the fuel consumption. The result is the fuel amounts and ignition timing are off.
What to Do About Sticking Gas Pedal
Driving a car with a sticking gas pedal is not safe. You must find out what the problem is and fix it right away. There are a few diagnostic techniques that may be used to find the problem. Here are the most common steps to take if your gas pedal is sticking:
Examine the gas pedal assembly – Try to find the problem by a visual inspection first. Move the parts by hand to check problems in the movement. Look for binding or linkage in the pedal arm.
Open the hood of your car and find the throttle cable. Observe the housing that surrounds the cable for movement, damage, or missing parts. Then check the throttle body and the carburetor. Have someone else move the gas pedal while you watch how the throttle lever moves. It should not bend or be loose. Lastly, disconnect the cruise control cables and the throttle. Check the lever to see if it rotates properly. If it doesn’t, there may be some obstruction in the throttle body. If not that, the spring may have failed.
Replace the throttle return spring – The throttle return spring is not expensive at all. It can be replaced with minimal effort to solve a very big problem. Not replacing a bad throttle return spring could cause mechanical failure. Test the spring before going on to more expensive solutions.
Throttle body cleaning or replacement – Cleaning the throttle body could solve the problem for a dirty butterfly valve or some other minor issues. The butterfly valve may be filled with gunk that can be removed with a cleaner. If the throttle body is beyond cleaning, it must be replaced. If the TPS needs replacing this requires professional knowledge and experience. Let a professional help.
Use an OBD2 Scanner – Use an OBD2 Scanner (view on Amazon) to identify the sticking gas pedal problems with your car. The computerized system will read the codes thrown for whatever has gone wrong under your hood. Here is one of the most common diagnostic trouble codes (DTCs) that may read if the gas pedal problem lies in the throttle:
The OBD2 error code P0068 “Manifold Absolute Pressure (MAP) Sensor/MAF Sensor/Throttle Position Correlation” code means that your car’s computer has identified inconsistency in the position of the MAF and the throttle sensor. An excessive input voltage signal degree variation has also been identified from the throttle sensor when compared to the MAF input signals.
Take your car to a repair shop – Driving when you know your gas pedal is sticking may sound trivial; but the problem could escalate to some serious engine damage. All this talk about throttle bodies, valves, and cables can be confusing. If you have no idea what the descriptions in this article mean, you should take your car to a repair shop. They can find the problem and get it right so that you can get back on the road safely.