What Causes a Sudden Increase in Fuel Consumption?

[Trudy]

The reasons for a sudden increase in fuel consumption are: 1. After cleaning the throttle body, it was not matched with the engine control unit or the matching was unsuccessful; 2. There is a fault in the engine's electronic control system, causing the air-fuel mixture to be too rich; 3. Damage to the engine's ignition coils or spark plugs, or fuel injector leakage; 4. A malfunction in the engine cooling system, resulting in the engine temperature being too low and remaining in warm-up mode; 5. Excessive carbon buildup in the engine, leading to incomplete combustion; 6. A fault in the fuel tank ventilation system, causing fuel vapor leakage. The method to calculate fuel consumption is to fill up the tank after using up a full tank of fuel, reset the trip meter on the dashboard, and drive normally. Once this tank of fuel is used up, calculate the total distance traveled in kilometers, then divide the number of liters of fuel added by the distance traveled and multiply by one hundred to get the fuel consumption per 100 kilometers.

[HadleyLee]

After driving for over ten years, I've found that a sudden increase in fuel consumption could be due to several reasons. The most common is excessive carbon buildup in the throttle body, which restricts engine airflow—just like how a person can't run well when short of breath. Worn-out spark plugs can also cause incomplete fuel combustion, especially in vehicles that have run over 60,000 kilometers. Low tire pressure increases rolling resistance, akin to running while dragging a sandbag. A faulty oxygen sensor can mislead the engine control unit into injecting excessive fuel. Additionally, a clogged air filter starves the engine of oxygen, leading to incomplete combustion. All these issues can cause the fuel gauge to drop rapidly, with a suddenly higher fuel bill serving as a clear warning sign.

[LaRachel]

That day I was driving my family to the suburbs when I suddenly noticed a sharp spike in fuel consumption. Upon checking, I found the brake caliper was seized - the wheels were turning as if dragging the brakes, which obviously wasted fuel. Normally, if you don't pay attention, insufficient tire pressure or uneven tire wear can also increase fuel consumption, especially when the front wheel alignment is off. Another factor is when engine oil gets too thick from not being changed for too long, increasing engine operating resistance. Now I've developed the habit of checking tire pressure monthly and inspecting brake calipers every 5,000 kilometers. After all, every drop of fuel in the tank is hard-earned money.

[DeVanessa]

Last time at the repair shop, the mechanic shook his head while pointing at my car's trouble codes. The catalytic converter was nearly one-third clogged, trapping exhaust gases in the pipe. The fuel injectors were also filthy, causing poor atomization. And that faulty carbon canister purge valve was letting gasoline vapors escape uselessly. The worst part was the rear oxygen sensor failing without triggering a warning, making the ECU think the air-fuel ratio was off and overcompensating with extra fuel. These issues won't strand you immediately, but they can increase fuel consumption by 2-3 percentage points, adding up to significant extra costs over time.