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Kristin Hunter

Kristi ... 5/11/2022

2016 Kia Forte SX 4 Cyl 1.60L


Car Bucks During Acceleration

Hi, I have a 2016 Kia Forte that just reached 112,000 miles, 4 cylinder engine, automatic transmission For about a month my car has been bucking when I accelerate, most often around 30-40 mph, worse on hills at that speed and when I'm lower on fuel, it has definitely gotten worse in the past month, I tried some fuel injector treatments with little to no impact. Took it to one shop and they said something was wrong with my transmission and that my transmission fluid "looked a little burnt". I took it to another shop, I told them I could put my car in all gears with no problems, was otherwise driving around normally, and no check engine light. After some time with my car, they said my throttle body needed replacement and recommended replacement of the accelerator pedal as well, and said my transmission was fine. I just had the work done (about $900) and my car is still jerking. It is somewhat better, the jerk happens less often, but will still jerk and fail to accelerate quickly mo

1 Answer


Jimm 5/12/2022

Do not simply throw parts and money at the problem.

Possible Causes of Engine Hesitation or Stumble:

Dirty fuel injectors (cleaning the injectors often fixes this).
Bad MAP (manifold absolute pressure) sensor
Bad TPS (throttle position) sensor
Bad or dirty MAF (mass airflow) sensor
Low fuel pressure (leaky fuel pressure regulator or weak fuel pump)
Vacuum leaks (intake manifold, vacuum hoses, throttle body, EGR valve)
Bad gasoline (fuel contaminated with water or too much alcohol)

Sometimes, what feels like a hesitation is actually ignition misfire rather than lean misfire. The causes of ignition misfire may include:

Dirty or worn spark plugs
Bad plug wires
Weak ignition coil
Wet plug wires


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