Q: Excessive fuel consumption

Hello. An excessively high fuel trim and decrease in fuel efficiency can be caused by many things. If you have already replaced the aforementioned components then I would move on to examining the vehicle’s engine management system. The fuel trim is adjusted by the computer, which receives its input from a series of sensors on the engine. A few sensors I would look at are the coolant temperature sensor, the manifold absolute pressure sensor, and the mass airflow sensor. All three of these sensors play an important role in fuel and timing calculations, and a bad signal from any of them may cause the computer to send the incorrect amount of fuel to the engine, resulting in your excessively high fuel trim and decrease in efficiency. As these sorts of issues can sometimes be difficult to diagnose, I would recommend having a professional technician look at the vehicle.