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Q: 05 Monty Carlo problem is hesitate and surgery between 45 to55mph. It is the throttle body sensor. It has 14400.00 miles replace

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The 05 Monty Carlo 14400.00 miles. Just began hesitate and surge. Did replaced plugs harness. I want to sell the car but in this condition no one will buy it at. Also replace motor mount. What do l do next.

There are quite a few possibilities that a mechanic would consider in diagnosing an engine hesitation issue. The most efficient thing is do is schedule a hesitation diagnostic and the responding certified mechanic will simply go through a diagnostic "decision tree" until the cause(s) is found. Just to give you an idea of the range of possibilities, though, faults in the mass airflow sensor, fuel pump, throttle position sensor, and fuel injectors can all cause a hesitation issue. The mass airflow sensor measures how much air is entering the engine and relays this information to the vehicle’s computer so that the right amount of fuel can be delivered from the fuel injectors. When a mass airflow sensor begins to fail, it will typically generate an error code or “Check Engine light.” This warning may be accompanied by hesitation while accelerating, or while driving up a hill. A vehicle with a failing mass airflow sensor may also stall soon after starting. The fuel pump in most modern vehicles sits inside the fuel tank and pumps fuel up to the engine. If a fuel pump cannot provide the correct pressure, fuel may have difficulty making it to the engine. A vehicle that hesitates while accelerating or while driving up a hill may have a weak fuel pump. The throttle position sensor tells the vehicle’s computer how far the throttle is open and how hard the accelerator is being pressed. The computer is then able to adjust the fuel/air mixture going to the engine so that is stays at an appropriate level. If the throttle position sensor is not working properly, it may be sending incorrect information to the vehicle’s computer. The computer may then not provide the engine with the correct amount of air while accelerating, causing a hesitation sensation. Fuel injectors spray fuel in a fine mist into the cylinder where it is mixed with air and ignited by a spark plug. Fuel injectors may become dirty over time and not be able to provide as much fuel to the cylinder as is needed. Dirty fuel injectors may cause the engine to run lean which will in turn cause hesitation when accelerating. If you schedule the recommended hesitation diagnostic, the mechanic will let you know which of these issues, or another one if applicable, is the cause of your car’s hesitation problem.

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