Poor gas mileage, especially a sudden drop in fuel efficiency, can be blamed on a number of issues. It can also be an indicator of a much more serious issue that if left un-repaired, can develop into an expensive repair.
There are dozens of problems that can lead to a drop in gas mileage, some of them are serious and some can be easily corrected. Here are some of the more common issues that can affect the fuel efficiency of most cars.
How this system works:
The fuel system stores and supplies fuel to the car to help drive the engine. Fuel is mixed with air, atomized and vaporized in the engine intake system. It is then compressed in the engine cylinder and ignited which produces energy to move the pistons. There are different engine layouts and designs but most of them work in the same basic way.
When the system is working as designed, and under certain conditions, maximum fuel efficiency will be achieved. Numerous factors can have an affect on fuel efficiency so it is usually a constantly changing number but a serious and sudden drop in miles per gallon is cause for concern and the vehicle should be inspected.
Common reasons for this to happen:
Dirty Oxygen Sensor: An oxygen sensor measures exactly how rich or lean the exhaust gases are when they leave the combustion chamber. The data is used by the vehicle computer to adjust the amount of fuel entering the engine. If the sensor is dirty or failing it can lead to a drop in miles per gallon. It can also lead to failed emission tests and a rough idle.
Dirty Fuel Injectors: Fuel injectors spray fuel into the cylinders where it is mixed with air and ignited. Over time the fuel injector system can become clogged. This can lead to a drop in fuel efficiency as well as slow acceleration and the car not having enough power. If caught early, simply cleaning the injectors can solve the problem. As it progresses, the injectors may have to be replaced.
Bad or Dirty Spark Plugs: Spark plugs ignite the fuel in the combustion chamber. If they are dirty or working incorrectly, it can cause the engine to misfire, leading to poor engine performance. This can lead to a lack of power as well as a big decline in fuel efficiency.
Malfunctioning Mass Airflow Sensor: A mass airflow sensor detects the amount of air coming into the fuel injection system. It delivers that information to the vehicle's computer, which crunches the numbers and then delivers the proper amount of fuel to the air in the vehicle. A dirty airflow sensor will degrade fuel efficiently and lead to a rough idle and even stalling as the problem progresses.
Misaligned Tires: Tires that are low or out of alignment can lead to a drop in fuel efficiency. Checking the tire pressure and have the alignment checked on regular basis can help prevent this problem.
Defective Fuel Pump: Fuel delivery issues can drastically affect fuel efficiency. The fuel pump pulls fuel from the gas tank to the fuel injectors. The fuel pump can become clogged or malfunction. A bad fuel pump can lead to a rough running engine because it is not getting enough fuel. This will lead to a decline in gas mileage. If this issue is not addressed it will lead to a rough, idle, sputtering and stalling.
Clogged Fuel Filter: A clogged fuel filter will also cause problems with gas mileage. The fuel filter screens out contaminants in the fuel, and over time it will become clogged. Fuel filters need to be replaced periodically.
Stuck Brake Caliper: A stuck caliper on a disc brake or a stuck shoe on a drum brake can lead to a serious decline in gas mileage. In addition, any brake issue can make the vehicle dangerous to drive. If the decline in efficiency is accompanied by the vehicle pulling to one side, the brake system should be inspected immediately.
What to expect:
A top-rated mobile mechanic will come to your home or office to determine the source and cause of the poor gas mileage issue and will then provide a detailed inspection report that includes the scope and cost of the necessary repairs.
How it's done:
A mechanic will inspect your fuel injectors, spark plugs, airflow sensor, tires and other important components to reach an accurate diagnosis. It may be necessary for the mechanic to test drive the car to produce acceptable results and pinpoint the source of the problem.
How important is this service?
A few of these issues are easy to fix but others are an indicator of a much more serious problem. Issues related to the fuel system will eventually lead to a rough running engine, stalling, and a car that won’t start at all.