Jerking and loses power when driving over 30MPH

Tiny
MGSHUMAC
  • MEMBER
  • 2014 MITSUBISHI MIRAGE
  • 83,000 MILES
When going over 30MPH, the car loses power and jerks as if I'm pumping the gas pedal, then releasing. Changed oil filter, cleaned spark plugs, cleaned throttle, changed the oil. Still no change and check engine light has not come on. If I floor the pedal, it goes fine, no jerking or losing power and RPMs. But as soon as I lighten the pressure and push the pedal the normal amount, it does it again.
Tuesday, January 18th, 2022 AT 8:59 AM

5 Replies

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
More than likely, we have an issue with the torque converter, but we need to confirm this is an auto transmission, manual, or CVT first.

Next, we need to check the fluid and find out if the fluid is full and in good condition. If it is not, we need to refill it and see if the operation is any different.

https://www.2carpros.com/articles/how-to-check-and-add-transmission-fluid

I don't expect this to fix the issue but if it changes the issue then we have internal issues with the torque converter.

What I suspect is happening is the converter is trying to engage but it is just slipping or not fully engaging and that is causing the vehicle to jerk.

We need to also check for codes and see if there are any that will point us in a different direction.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Let's start with this and go from there.

Thanks
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Wednesday, January 19th, 2022 AT 2:51 PM
Tiny
MGSHUMAC
  • MEMBER
  • 3 POSTS
No check engine light has come on. It's an automatic transmission.
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Wednesday, January 19th, 2022 AT 5:34 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Okay. It is worth checking the codes even if there is no light. However, assuming there are no codes then we need to check the trans fluid because that is going to give us a sign if this is the issue.

Basically, we need to find out if there is excessive heat in the transmission and the fluid will tell us that by its condition.
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Wednesday, January 19th, 2022 AT 6:19 PM
Tiny
MGSHUMAC
  • MEMBER
  • 3 POSTS
All of the fluids were checked and are at good levels. Gave the car an oil change as well. It's not overheating at all, and it doesn't do the loss of power every time that I drive, only most of the time.
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Thursday, January 20th, 2022 AT 5:31 AM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Okay. That is good info. Since this does not happen all the time then we need to drive it and monitor all the typical sensors like the throttle position sensor, MAP, and temperature sensors.

Here is a guide that talks about low power issues:

https://www.2carpros.com/articles/symptoms-of-low-engine-power

Basically, we need to use a scan tool to find out what these are reading when the issue is not happening and then what it does when it does.
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Thursday, January 20th, 2022 AT 12:14 PM

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