Struggling to press down on your gas pedal can be frustrating and potentially dangerous. It can feel like you’re driving a tank instead of a car. In this article, we’ll explore some common reasons why your gas pedal may be stiff and what you can do to fix it.
Reasons Why Your Gas Pedal Is Stiff
Dirty throttle body
A dirty throttle body is the most common cause of a stiff gas pedal. It causes problems with the gas pedal due to a build-up of dirt, grime, and carbon deposits which stick onto the throttle plate.
When you press the gas pedal, the same input is applied to the throttle plate, so if it’s clogged up with dirt, you will get a stiff gas pedal. You may also experience other issues because of an imbalance in the air-fuel mixture combusted in the engine, such as delayed accelerator pedal response, poor fuel efficiency, rough idling, and reduced engine performance. The throttle plate can also get stuck in a partially open position, meaning the engine will continue to rev (hunt) when the pedal is released.
Not changing the air filter regularly is the most known cause of the throttle plate getting dirty. The Filter gets clogged up, and eventually dirt forces its way through the filter, which gets stuck onto the throttle plate.
Another cause is lots of slow driving in slow traffic, where your engine is more likely to suck in carbon and soot from other vehicles; removing soot and carbon requires a special filter which standard car air filters cannot remove.
Jammed throttle cable
Most modern vehicles don’t use throttle cables; instead use an electronic throttle control (ETC) system, known as drive-by-wire, which uses electronic sensors and actuators to control the throttle. However, throttle cables are still used in older vehicles or specific applications. Throttle cables run from the back of the gas pedal to the throttle body. When you press the pedal, the same effort is applied to the throttle body, opening it.
If a throttle cable becomes dirty, rusty, or damaged. It can get caught and jam into position, causing the gas pedal to stick or become stiff to press. When a throttle cable jams, it can prevent the throttle from returning to its idle position smoothly or restrict the throttle from opening fully, causing the gas pedal to stick.
It may be possible to free off a throttle cable by cleaning any parts jammed with WD40, especially if it’s caught a rubber bung or one of its guides. However, when there is an issue with the throttle cable, you would expect to replace it.
Obstructions to the pedal
Behind the back of the pedal is a good place for rocks and dirt to gather, obstructing the back of the pedal. Floor mats are also bad for getting caught behind the pedal, meaning you can’t press it fully.
Construction worker machinery and vehicles are bad for dirt getting caught behind the pedals; they tend to drive with land on their boots which dries and gathers at the back of the pedals.
A quick clean of the obstructions behind the pedal, and it should return to normal. Pay attention to any springs or hinges that can have a build of dirt; if they are not cleaned, the pedal may move better, but not entirely as it should be.
Pedal mechanism failed
The gas pedal has mechanical components, such as hinges, springs, and pivot points, allowing it to move smoothly. It’s not common for these to break for anything other than age related corrosion. Either one of 2 things happens when a spring or hinge breaks, the pedal becomes stiff, or it sinks to the floor and doesn’t come back up.
If a spring breaks, you can usually get a replacement from the dealership; however, if a hinge breaks, you typically need to replace the whole gas pedal unit, which disappears under the dashboard and goes through the firewall into the engine bay. They can be a little tricky to replace and may even require removing most of the bottom of the dash.
Electronic throttle control issues
Vehicles with electronic throttle control (ETC) systems can get issues with the electronic sensors, actuators, or wiring that control the throttle, which can also cause the gas pedal to stick. For example, a malfunctioning throttle position sensor (TPS) or accelerator pedal position sensor (APP) can send incorrect signals to the engine control module (ECM), resulting in a sticky or stiff gas pedal.
How to Fix a Stiff Gas Pedal
If removing or hoovering up debris behind the pedal doesn’t solve the problem, the most common cause of a stiff gas pedal is an issue with the throttle body.
The best way to clean a dirty throttle body is to remove it from the car first. Get a toothbrush, brake, and clutch cleaner, and give it spray and a good scrub to remove dirt and grime from the throttle plate. Wipe away the dirt from the throttle body with a clean microfibre cloth. Do not use any water. You will know it is clean as you should be able to push the throttle plate open and immediately close shut if it doesn’t or only partially closes. Keep cleaning.
You can clean a throttle body while it remains on the car in the same way. However, all the dirt and grime you clean from the throttle body will get sucked into the engine and may clog up a sensor on the way in, causing another problem.
If cleaning the throttle body doesn’t solve the problem and the car is drive by wire, the vehicle will need to be plugged into a diagnostic machine to check for any issues with sensors or actuators.
How to Prevent a Stiff Gas Pedal
Keeping the car interior clean and making sure to clean behind the gas pedal will prevent debris causing a stiff gas pedal. in order to prevent the throttle body from getting clogged up you should service the car regularly and ensure the air filter is changed annually. These are the best and only preventative measure you can take.
Can You Drive With a Stiff Gas Pedal?
The problem with driving with a stiff gas pedal is who knows when it will no longer return. If the cause of the stiff pedal is a dirty throttle body, it may jam open, meaning the engine will constantly be at max RPM, which isn’t good for a motor.
If the problem is related to the pedal, i.e., a spring or pivot point, the pedal may suddenly go so stiff you can no longer press it or go so loose that it drops to the floor and doesn’t spring back up. Either way, driving with a stiff gas pedal is a bad idea.
If the pedal suddenly goes stiff while driving, it would be best to pull over and check that nothing is caught behind it. If nothing is there, have the vehicle be recovered to a mechanic. Diagnosing and fixing this type of problem at the side of the road will be very difficult.
Key Take Away
The two most common causes of a stiff gas pedal are debris obstructing the pedal or a dirty throttle body. Cleaning the throttle body is very simple, and it can be carried out by almost anyone with a toothbrush, a clean rag, and a bit of brake and clutch cleaner. Once the throttle body is cleaned, the pedal should return immediately to its normal action if it doesn’t has the car inspected by a mechanic, as the cause is likely something completely different.
