Q: My car hesitates and I have to press on gas hard for it to kind of smooth on out.

asked by on

Well when taking off my car hesitates, make rumble noises and shakes a little bit
My car has an automatic transmission.

Typically, what you are describing is due to an engine management fault(s) and such faults occur in ignition system components, the fuel system, and/or the air induction system. A possible first approach is to just simply make sure that the spark plugs are not past due for replacement and that all other engine maintenance is up to date. If the problems remains unresolved, one would request a diagnostic for poor or rough acceleration.

There are quite a few items to consider during such a diagnostic, but here a few major items:

Mass Airflow Sensor: 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.

Fuel Pump: 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.

Throttle position sensor: A 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.

Dirty/failing fuel injectors: 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.

To resolve the issue, please request a diagnostic for poor or rough acceleration. If you have additional concerns or questions, don’t hesitate to re-contact YourMechanic.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1,000 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
  1. Home
  2. Questions
  3. My car hesitates and I have to press on gas hard for it to kind of smooth on out.

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: My check engine light is on , mechanic said it is catalyst converter however the car run perfectly fine , no misfire or more

The impact on engine operation (and fuel efficiency) of a "failed" catalytic converter depends on exactly what the failure mode was. In one scenario, if the catalyst within the converter is simply "poisoned" and thus there is no longer any...

Q: My serpentine belt came undone but it isn’t showing tear and wear. What made it come undone completely?

Hi there. Typically when a serpentine belt falls off intact, it's due to a failed belt tensioner or pulley. It's best practices to replace the pulley's and tensioner when you install a new serpentine belt.

Q: Q: Fuel pump

This may happen when the fuel pump is working intermittently or not maintaining the proper fuel pressure. This may also be related partially to the fuel pressure regulator which helps to maintain the proper fuel pressure throughout the system. When...

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...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.