Mechanic & Fuel Economy Diagnosis for Cowandilla

This page is about fuel economy getting worse, which is one of the more common reasons people book a car in and one of the easier things to work through methodically.

Trip computers estimate. They drift, and they are affected by driving pattern in ways that make comparisons unreliable.

Measure it properly at least once: fill the tank, reset the trip meter, drive normally, fill again, and divide litres by kilometres. Do that twice before concluding anything, because one tank can be misleading.

Also account for what has changed. Cold weather, more short trips, roof racks left on, a load carried permanently, or more air conditioning use will all move the figure without anything being wrong.

Tyre pressures. The single most common cause and it costs nothing. Underinflated tyres increase rolling resistance measurably. Check them monthly, cold.

A dirty air filter. Restricts airflow, which the engine compensates for. Cheap and quick.

Dragging brakes. A seized caliper slide or a sticking park brake makes the engine work against the brakes continuously. Often noticed as one wheel being hot after a drive, and worth checking because it is a safety item too.

Oxygen sensors. These measure exhaust oxygen so the engine can set the mixture. They age and become slow rather than failing outright, and a lazy sensor runs the engine rich without necessarily setting a fault code. This is the classic cause of gradually worsening economy with no warning light.

A misfire or a fault the engine is compensating for. The engine management adds fuel to work around problems, and it will do so quietly.

A mechanic Cowandilla drivers bring this to should be reading live fuel trim data, because that shows whether the engine is adding fuel to compensate and roughly how much.

Driving pattern changes more than any component. A commute that changes from open road to stop-start will move consumption substantially with nothing wrong at all. Worth ruling out before spending money.

2/208 Grange Rd, Flinders Park, four minutes from Cowandilla. Bring the figures and a mechanic Cowandilla drivers use can work through the list quickly.

Call (08) 8443 7900.

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