COMMON FACTORS AFFECTING FUEL ECONOMY, AND POSSIBLE CAUSES OF POOR MPG
If your vehicle is running less economically than it used to, there could be an underlying issue with mechanical parts, electrics or even sensors.
This guide covers SOME of the most likely issues which could be attributed to reduced fuel efficiency.
DRIVING STYLE AND OTHER CONDITIONS
Possibly the most common cause of poor MPG returns is your driving style and the type of journeys you do.
For example, if you do a lot of stop-start type driving (typically in heavy traffic or traffic jams) or you use the throttle for more rapid acceleration than normal, fuel consumption can increase quite dramatically.
Driving in a hilly area or towing can also have a dramatic effect, these are factors that you may or may not be conscious of all the time due to other things on your mind.
AGGRESSIVE DRIVING STYLE
Cars are least efficient during initial acceleration, so if your car journey is short or involves a lot of stops then you will use more fuel than on longer journeys where your speed and acceleration are more constant.
More aggressive driving where you accelerate hard and brake late uses much more fuel than steady driving. For best mpg results, try keep your vehicle moving as much as possible by leaving plenty of room between you and the vehicle in front.
Modern vehicles have a mass of sensors, with many being essential to the efficient operation of the engine.
Sensors are designed to send information to your vehicles ECU (brain) where the data lookup tables (MAP software) sensors that become less efficient or inaccurate, feed the ecu with incorrect information and affect performance/efficiency.
MAF (“mass airflow” sensors) play a huge roll in engine efficiency and although they do not always show up on a basic diagnostic test, they can still be responsible for poor efficiency.
Having a dirty or faulty mass air flow sensor can reduce mpg by 20% or more because the sensor provides incorrect information the engine management software, which in turns miscalculates how much fuel is required.
The engine’s thermostat controls the operating temperature of the engine, helping the engine warm up quickly after a cold start.
A faulty thermostat does not close properly, which could mean that the engine never reaches a desired operating temperature, and a cold engine uses more fuel.
FAULTY FUEL INJECTORS
Fuel varnish deposits can build up inside fuel injectors which prevents them from delivering the correct volume of fuel, which in turn can cause poor fuel economy.
Engine misfire could be the result of many factors, defective fuel injectors, faulty spark plugs, bad plug wires, fuel injectors, low fuel pressure amongst others but ultimately, will waste fuel and reduce MPG.
DIRTY AIR FILTER
If your air filter is partially blocked, it reduces air allowed into the engine and interferes with normal engine performance causing poor fuel economy and general efficiency.
Most modern vehicles use a low viscosity motor oil, that tends to thicken in colder weather conditions. Using a motor oil with a higher viscosity than you need can cause poor fuel economy, so check your vehicle manual for the correct oil grade required for your engine.
EGR VALVE LEAK
The EGR Valve (Exhaust Gas Recirculation Valve) is a device which is designed to help control emissions. If the EGR valve is not operating correctly it can allow exhaust gases to leak back into the intake manifold causing misfires and in turn a reduction in mpg.
TYRE PRESSURES AND TYRE TYPE
The type of tyre you use and the pressure can have a major impact on your fuel economy.
If your tyre pressures are low, rolling resistance is increased and your engine will have to work harder to propel you along.
The harder your vehicle works, the more fuel it will use.
Equally, better quality tyres often have less rolling resistance and therefore are more economical in the long run. For confirmation of this factor visit a well know tyre company site www.blackcircles.com (we are not affiliated) and check out the ratings for various tyres, which include fuel economy data.
ECU REMAPPING BENEFITS
Assuming that all other aspects of your vehicle are in good order, a professional ecu remap can typically improve fuel efficiency by 10-20% or more...
Combine a well-maintained car with a professional ecu remap and improved driving style, and some people could enjoy improvements of up to 30% or more.