Why does my car lose power uphill?

What you need to know:

  • The engine management system or Engine control unit (ECU) which determines air fuel ratio which affects fuel burning or Engine power, also has to be examined in case any of its sensors are faulty. Spark plays a crucial role during prompt ignition and acceleration.
  • This information is crucial for the ECU and affects acceleration quality. Other engine management sensors to be examined are oxygen sensors in the exhaust which help the ECU regulate fuel air ratio. The engine management system can be interrogated with a computer diagnostic tool to reveal diagnostic tools which usually guide us to decide which of the above components have failed.

Hi Paul, I religiously follow your car tips every Thursday. I have a concern about the poor acceleration uphill of my Land Rover Discovery ii V8 with a 4.0 litre petrol engine. I am wondering what the cause of sudden loss of power could be. How can I solve it? Angella Nalule.

Hello Angella, poor acceleration of a petrol powered engine like the one on your Land Rover usually exhibits symptoms such as engine hesitation or lack of normal power when you need it either driving up hill or during quick acceleration.

This situation is most common in petrol powered vehicles (regardless of model or make) with mileages around or above 100,000 kilometres.

I always start with the obvious issues which are central to engine performance: spark, fuel and air supply.
The engine management system or Engine control unit (ECU) which determines air fuel ratio which affects fuel burning or Engine power, also has to be examined in case any of its sensors are faulty. Spark plays a crucial role during prompt ignition and acceleration.

This can be affected by low ignition coil voltage from bad coils or damaged high tension lead circuits. Severely worn out spark plugs can impede prompt acceleration.

Fuel supply to the engine can be affected by a dirty clogged fuel filter or fuel injectors which alter the fuel supply pressure and prevents smooth prompt acceleration.

A dirty air filter reduces clean intake of air supply which alters the air fuel ratio and leads to poor acceleration. Along the air intake tunnel, the throttle potentiometer is another component to examine.

This unit regulates the amount of air delivered to the combustion process in the engine. The throttle valve can accumulate deposits which affect how fast it closes or opens to admit air.

An associated throttle position sensor sometimes fails and can send wrong data to the engine computer which in turn delivers wrong fuel amounts.

The mass air flow sensor next to the air filter housing sometimes fails to carry out its role of metering intake air volume and temperature.

This information is crucial for the ECU and affects acceleration quality. Other engine management sensors to be examined are oxygen sensors in the exhaust which help the ECU regulate fuel air ratio. The engine management system can be interrogated with a computer diagnostic tool to reveal diagnostic tools which usually guide us to decide which of the above components have failed.