In Summary

When you cannot pick up speed in your vehicle, it does not necessarily mean that your engine is faulty. It means there is some component of your vehicle which is malfunctioning and not allowing your engine to handle these fast acceleration demands.

Francis Gumisiriza drives a 1999 model Toyota Premio. Much as he likes its economic fuel consumption aspect and the accessibility of most of its spare parts on the local market, he is quick to observe that it is not a fast car, the more reason he is contemplating putting it up for sale at the end of the year.
“One day I set off from Fort Portal at 7am and wanted to be in Kampala for a meeting at 1pm. When I reached Kyegeggwa, I noticed the car was not picking speed much as I continued to accelerate. Whenever I increased the speed to 120km per hour, the car would become light and I could not accelerate further. I chose to drive between 90 to 110 kilometers per hour,” Gumisiriza recalls.
“Even at a stretch where it was all clear to overtake some slow trucks with no oncoming traffic, the vehicle could not pick up speed,” he adds.
Experiences like Gumisiriza’s are common especially along highways. You are driving at, say, 120 kilometers per hour yet another motorist overtakes you at a much faster speed, leaving you wondering if you are driving at 20 kilometres per hour or less. Hakim Kimera, a mechanic in Wandegeya, observes that your vehicle’s inability to pick up speed does not apply to one or two types of cars. It is a problem that cuts across all car types irrespective of their model and this is due to a number of causes.

Clogged or dirty fuel filters
The most common reason why your car does not pick up speed even when you step on the accelerator, he states is mainly due to clogged or dirty fuel filters.
“Fuel is supposed to run throughout the engine when on the road. When it is blocked from flowing to the engine by dirt in the fuel filter, it means your engine will not be receiving the required or sufficient fuel to run effectively. It will automatically slow down,” Kimera explains.

Gear confusion
Gear confusion, Kimera opines, mainly happens in vehicles with automatic transmission systems. Quite occasionally, some drivers shift the gear stick from the drive (D) position to neutral (N) especially when going down the hill, all in the name of saving fuel. “As you drive up the hill, you forget to shift the gear stick from the neutral position back to the drive position. When the gear stick is in neutral and you accelerate, your vehicle will not pick up the required speed,” Kimera notes.

Faulty computerised system
Vehicle manufacturing technology advances almost on a daily basis. As such, many car manufacturers are producing cars with modern technology systems and features that the driver uses to control and run the car with just a click or touch of a button away. “If the main computer system that controls your car experiences a fault, it will automatically have an effect on the vehicle speed when you accelerate. The system will limit or control the speed beyond which your car cannot drive at,” says Martin Muwonge, a mechanic at City Oil Bweyogerere.

Engine light on dashboard
Muwonge says some drivers tend to ignore the check engine light when it displays on their dashboard as long as the car can still move. By the time the light manifests, it could be a signal that something is not right in your car engine, which Muwonge refers to as the heart of the car.
“If the engine light goes on without ceasing, there could be an electric problem in your engine that controls the speed at which the engine runs the car,” Muwonge says.

Leaking fuel injector
The fuel injector plays an important role of supplying fuel to the engine compartments of your car. If there is a leakage in the injector, it means your engine would not be receiving the required fuel to run efficiently.

Oxygen sensor problems
According to, an online portal, the function of the oxygen sensor is to keep track of the car’s exhaust emissions and determine the amount of fuel that is needed in the internal combustion chamber by tracking the air to fuel ratio. If the oxygen sensor were to malfunction, the wrong amount of fuel would get burned during the combustion process. This would create a rich fuel mixture, which would result in slow acceleration as you step on the gas pedal.
Other reasons why your car will not pick up speed when driving could be due to an old or poorly connected timing belt and an overheated car cooling system, among other mechanical problems.

Worn out spark plugs – The internal combustion engine of your vehicle relies on the spark plugs for transmitting the electrical signal from the ignition coils to the internal combustion chamber. Once that happens, an electric spark ignites the mixture of fuel and air. Therefore, if you have faulty spark plugs that cannot transmit this electrical signal, then the performance of your engine will weaken and you will not be able to accelerate as fast.

Faulty Ignition Coil–The ignition system has ignition coils which convert 12 volts of power from your battery into the 20,000 volts of power needed to ignite the engine. If you were to have a faulty ignition coil, then the mixture of fuel and air inside the engine would not be ignited adequately. This means you would lose power as you put your foot on the gas pedal.

Car maintenance

The care that you give to your car does not only determine how long it lasts but it also determines its performance on the road. This kind of care is mainly in car service and maintenance.

Service your car regularly
Jimmy Ssebadduka, a mechanic at Shell Jinja Road, says by maintaining your car, you have to occasionally to change the oil, air and fuel filters to rid them of any dirt that might reduce engine performance.
“When you buy your car from the bond, take it to the service station and have it inspected to determine if the fuel, oil and air filters can still be used for some time. The presumption is that all cars in bonds except those that are brand new have already been used and some parts ought to be changed by the new user to obtain maximum car performance,” Ssebadduka explains.

Keep an eye on your tyres
In most cases, your car’s acceleration speed is determined by whether your tyres have treads or not.
“If your tyres have treads, they will have maximum contact with the ground, thereby guaranteeing you maximum acceleration. If they have no treads, the level of acceleration will be compromised,” he says.

Reduce weight in your car
There is a misconception that when your car is loaded, the weight increases its stability on the road. This, Ssebadduka says, does not only increase on or lead to more fuel consumption but that it also slows down acceleration. Therefore, to increase acceleration whether on a tarmac or murrum road, he advises is in reducing on the weight in your car, whether it is luggage or limiting on the number of car occupants.