Skip the auto shop - Our mechanics make house calls

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

asked by on

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.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!
  • Home
  • Questions
  • 05 Monty Carlo problem is hesitate and surgery between 45 to55mph. It is the throttle body sensor. It has 14400.00 miles replace

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Check engine light readsP0102, twice I've changed the mass air sensor. Check engine light is on. Repaired ecm as well

The problem may be with the mass air flow sensor (MAF sensor) connector. Start the engine and wiggle the connector. If the engine RPM starts to change or the engine performance changes, you'll know the connector is to blame. ...

Q: Gears slipping

Hi there. This can be caused by a problem with the valve body in the transmission or maybe the start of a serious engine failure. When you start the vehicle, it will cause the circuits to reset in the valve...

Q: Car hesitates and stalls ocassionally - 1994 Cadillac Brougham

Hello. The EGR valve is most likely not closing all the way when stopping due to the carbon getting in the pintle and holding it open. Then when you go to start it, it opens and releases or breaks the...

Related articles

How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...