10 Causes of Car Engine Hesitation When Accelerating

(Updated on June 30, 2020)

Car engine hesitation is a noticeable problem that can occur as you’re driving. When you go to step on the gas pedal to accelerate, you will suddenly feel like the power has been lost in the engine for a couple of seconds.

Instead of going faster by stepping on the accelerator pedal, the speed will be reduced. The vehicle may even stumble entirely during these seconds. This is what it means when the car engine hesitates.

It is usually the result of a problem with the air and fuel mixture within the combustion chamber. However, there is a long list of other reasons which could be the cause of this hesitation problem too.

Top 10 Reasons Your Car Hesitates When Accelerating or Driving

One thing is for sure, you won’t be able to drive safely if your engine keeps hesitating while you’re on the road. You will need to figure out the cause of this problem and get it fixed by an experienced mechanic.

In any case, you will likely find the problem relates to an imbalance in fuel and air mixing in the chamber. Either there will be too much air or fuel, or too little. To help you pinpoint the cause of this problem, below are 10 of the most common causes of engine hesitation while driving.

1) Bad Throttle Position Sensor

bad throttle position sensor TPS

The throttle position sensor monitors the throttle valve’s position and then relays this information to the engine control unit. This helps sustain the proper air and fuel mixture while the vehicle is in use.

If this sensor goes bad, the engine control unit will be unable to keep the right balance in the mixture. Replacing the TPS is the only solution.

2) Vacuum Leak

vacuum hoses

If any of the vacuum hoses around your engine become damaged or worn out, you could experience air leakage from them. Then you will experience engine hesitation which is most noticeable at low RPM. Repair or replace any hoses which are causing the leak.

3) Faulty Fuel System

If any of the components in your fuel system stop working correctly, like your fuel injectors, fuel pump, or fuel pressure regulator, then your engine won’t get the proper amount of fuel it needs for combustion. This will cause your engine to lag, stumble, or hesitate.

4) Faulty Ignition System

dirty spark plug

If there is a problem with your ignition system, such as with your spark plugs, rotor, or wires, then your engine will lose power at inconsistent times. This will cause hesitation as you accelerate.

5) Dirty Fuel Injectors

fuel injectors

If you have not cleaned your fuel injectors for a long time, then they’re probably corroded with carbon deposits or other debris. If you let your fuel injectors continue to be dirty, then it will impact how much fuel gets injected into the chamber.

A good fuel injector cleaner is often a good, cheap fix that will restore proper fuel flow from the injectors. If that doesn’t do the trick, you may need to have them professionally cleaned or simply replaced with new fuel injectors.

6) Bad Oxygen Sensor

bad oxygen sensor

The oxygen sensor is responsible for calculating the amount of oxygen that was not burned in the exhaust system. Based on this information, the engine control unit will know if there is too much or too little oxygen being ignited in the chamber.

If the oxygen sensor is not working properly, then the proper air and fuel mixture cannot be achieved.

7) Faulty Mass Air Flow Sensor

bad maf sensor

When outside air goes into the engine as part of the combustion process, the mass air flow (MAF) sensor measures how much of this air is going in. This helps the engine control unit determine the right amount of fuel to inject into the chamber.

But if this sensor is bad, then the wrong amount of fuel will get injected and cause engine hesitation.

8) Bad Manifold Absolute Pressure Sensor

bad MAP sensor

The engine control unit depends on the MAP sensor to determine the engine load. This is how the timing of fuel injections into the chamber is made. If the MAP sensor is not working, the engine control unit won’t know how much fuel to inject in order to accommodate the given engine load.

9) Faulty Exhaust Gas Recirculation Valve

bad EGR valve

The exhaust gas recirculation valve, or EGR valve, may be damaged and causing a leak. This is known to cause engine hesitation problems, so it should be addressed.

10) Bad Fuel

bad gas in car symptoms

If you are using bad fuel which is has been sitting in your tank for too long or is too low of an octane for your engine, it can cause many different problems. Hesitation will be the beginning of your troubles so look at it as a warning sign if you notice your engine hesitate when you accelerate from a stop.

41 thoughts on “10 Causes of Car Engine Hesitation When Accelerating”

  1. My stabilize traction control light came on but went off now check engine light is on and my car hesitates when I step on the gas and go up a hill I got a 2011 Chevy cruze

    Reply
    • Sounds like your car is entering limp home mode. If this is the case, it means something has gone wrong with the car that makes the engine or transmission computer think it needs to run a really conservative calibration to protect the powertrain. I’d visit a mechanic to get it checked out as soon as possible.

      I recently wrote an article on limp mode, which is due to be published soon. Check back in a few days if you’re interested.

      Reply
      • Nissan sentra 2012
        My car hesitate on red light. We changed spark plug, fuel filter, transmission fluid, engine oil, engine filter, and clean throttle body, change air flow sensor. Still my is not starting smoothly.

  2. We found my car was hesitating and stalling when I took off from a stop or went up a hill because after 24 years, the motor mounts were worn and that caused rubbing of the wire harness and some of the wires had the insulation rubbed off, causing shorting. Thank Heavens for my wonderful mechanic who found and fixed this! (This after we changed the fuel filter.)

    Reply
  3. My 2008 nissian Altima is hesitant when going up a hill or accelerating I’ve changed the fuel pump the air filter and the air intake hose but it is still having the same problem

    Reply
  4. You might need to replace your MAF sensor which is your mass airflow sensor and definitely check your fuel rail and fuel injectors. If still having issue after that let me know

    Reply
  5. I was wondering why does my car lose power/jerks and hesitates to accelerate when I’m close to the E I’ll have 60 miles of fuel left and it starts to act weird

    Reply
    • Perhaps there’s a lot of sediment at the bottom of your gas tank, perhaps your fuel gauge is reading incorrectly, or perhaps you need to change the fuel pump or fuel filter. I’m not sure.

      Reply
  6. My car stalls when I’m getting ready to pull of at a light and when I hit the gas I have hit hard for it to go and I have my fuel pump changed I have transmission leaks they were fix it just started doing it a few minutes and my car knocks while sitting a light and rattles when I take off sometimes

    Reply
  7. I have a 1991 Toyota MR2 with a 2.2 liter engine and 5-speed stick. It has started bucking under load, feels like it is losing a cylinder when accelerating and I get a sweet smell like kerosene. Fuel mileage is bad now as well. Drives fine otherwise. I have changed the TPS, coil, coil igniter/module, plugs, cap, wires, rotor. Plugs are burning cocoa brown/tan. Idles a little rough at times as well. Getting ready to change the up-line O2 sensor(s) and then maybe the MAP if the O2s don’t work. No noticeable vacuum line cracks/breaks. Thanks to this article I will also try cleaning the MAF but It still does it with the air cleaner disconnected but it is worth a try.

    Reply
  8. Why would my 2004 Dodge ram 5.7 keep throwing a map sensor code and I changed out the senser and the computer and now that I have a new computer it hesitates on takeoff

    Reply
  9. my jeep hesitates to accelerate and other times it’s running great.Took it to get diagnosed and they say nothings wrong. Any suggestions?

    Reply
    • You could check basic things like spark plugs and wires, injector functionality, and engine air filter cleanliness. Can you narrow down when it hesitates? Is it just on cold start, certain ambient temperatures, etc?

      Reply
  10. My 2001 Acura TL is starting to hesitate when accelerating, then starts slowing down. I know my transmission is bad but is that all?

    Reply
  11. My Nissan Macra car hestates when pressing the gas pedal, it acts like losing the power!

    What could be the cause? I put my fuel pump direct without a return pipe.

    Reply
    • I’m not sure. Have you checked the spark plugs? Sometimes this can be a quick, cheap, easy fix for initial stumbling and hesitation when you step on the gas.

      Reply
  12. I have a 2014 vw tiguan and it seems to be hesitating only when it’s hot outside (85+ degrees) it will trip a check engine lean code but if I clear it and drive during cooler temperatures it drives perfect.

    Reply
    • I’m not sure. If it were my car I might hook up a scanner and check short term and long term fuel trims. Observe where they sit both when it’s hot and cold outside. Any misfire codes? The car may be pulling timing for some reason when it’s hot.

      Reply
  13. Changed my spark plugs new valve cover gaskets oil on dip stick looks clear though had fuel in oil but tried igniting the oil on dip stick , nothing . It is a 350 it did over heat but head gasket good no water in oil or over heating . Also carbureted It idles fine revs up fine takes off fine but when get it under load starts bucking and more gas you give the more it wants to die . I cleaned the carb and put some sea foam in it ..noticed have oil on spark plugs on threads and getting down into chamber . Not just one plug like three on pass side maybe one on other side .. now not smoking so. I’m hoping not needing internal work .. wondering if oil on plugs could be cause faulty manual fuel pump 0 2 sensor ,don’t hear any vacuum leaks.. just seeing if one those could be the problem before start tearing down to see if o ring or piston rings are causing oil to fouling my plugs .just with not smoking maybe just fuel problem not enough or coil not getting hot enough ?

    Reply
  14. My Toyota Corolla Sport 2003 model started hesitating while at speed, I consulted mechanic and they change fuel pump, filter MAF, check the throttle position sensor, it’s like it’s not working, I have to start twice unlike before.. what should I do?

    Reply

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