Hesitation while acceleration

DALTON HAMILTON

MEMBER
2004 HYUNDAI SANTA FE
2.4L
2WD
AUTOMATIC
235,000 MILES

While driving it'll start to either hesitate or jerk and it usually happens when I'm at 30 miles an hour or faster. It recently started happening as I take off from stop it doesn't I'll hit the gas pedal but it does not go at jerks it takes a minute and hesitates and then it'll jerk forward and then it continues to do this the entire time I'm driving. I've replaced every different sensor I've replaced the throttle body and it's still doing it. Why?

1 Reply

JACOBANDNICKOLAS

MECHANIC
109,867 POSTS

Hi,

When this happens, does the engine rev and the vehicle jerk or does the engine actually seem to act this way? Also, have you checked for diagnostic trouble codes? Since you have replaced sensors, I suspect you have, but if you haven't, it should be done.

Here is a quick video showing how it's done:

https://youtu.be/b2IJGfImVvw

If you do have a scanner with live data, can you tell me what the fuel trims are?

If it is the engine and not the transmission jerking in to gear, I suspect it could be a fuel pressure issue or a crankshaft position sensor issue. You may have already replaced the sensor. If you haven't checked fuel pressure, I suggest doing that. Here is a link that shows how it's done. You will need a fuel pressure gauge, but most parts stores will lend one to you if needed.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

The picture below shows the manufacturer's pressure specifications.

Let me know if if the crankshaft position sensor has been replaced, if there are any other symptoms, or anything you can think of that may help. For example, have you checked for engine vacuum leaks?

Take care,

Joe

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