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Need help...ACCELARATION getting weird :(

Hello everyone, I have a 01 Kia Optima, it is an automatic...Lately, my car has a problem where when I step on the gas pedal there are no accelaration then couple seconds later it start to kick in...feel like losing power...Sometime the car JERK really strong or rock back and forth for couple seconds then it run normal again. Also, the RPM keep going up and down like crazy...Sometime when I'm driving, I need to let go the gas pedal then step on it again so the car able to accelaration...I want to fix THE problem but have no clue what wrong or where to start...So, any suggestion or help would be great. Thanks a lot for helping!

Reply to
vannie402 via CarKB.com
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Reply to
Phil

I go to O'Reilly and have a code check...the code came out that my car has a bad speed sensor and misfire in cylinder 2. Does anyone know where the speed sensor located at and how to change it? Also, what can I do about the misfire on the cylinder? Thanks for all the help!

Reply to
vannie402 via CarKB.com

"vannie402 via CarKB.com" wrote in news:6b9934de69c94@uwe:

Specify the exact error codes. The transmission has sensors on both the input and output shafts and a vehicle speed sensor. Failure of either shaft sensor can send the transmission to 2nd or 3rd gear in failsafe mode, which may explain the erratic RPMs when this happens. You can see the online shop manual here:

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The misfire could be as simple as a worn spark plug or cable. Since your car is over 5 years old, it could be time to replace them.

Reply to
Jeff

The code is P0720...Also, when I try to use the online shop manual there are

2 model for the Optima...MS and MG. Which one is for my car and what is the different between? Thanks,
Reply to
vannie402 via CarKB.com

"vannie402 via CarKB.com" wrote in news:6ba52ce27e564@uwe:

P0720 is for the output shaft sensor. "If the output from the output shaft speed sensor is continuously 50% lower than the vehicle speed for 1 second or more while driving in 3rd or

4th gear at a speed of 30 km/h or more, it is judged to be an open circuit or short-circuit in the output shaft speed sensor and diagnostic trouble code No.P0720 is output. If diagnostic trouble code No.P0720 is output four times, the transmission is locked into 3rd gear or 2nd gear as a fail-safe measure."

Probable causes "Malfunction of the output shaft speed sensor Malfunction of the transfer drive gear or driven gear Malfunction of connector Malfunction of the TCM"

The sensors are on top of the transmission.

MS is for the original Optima model 2001 - 2006. MG is for the newer model 2006 1/2 - 2007.

Reply to
Jeff

Is it easy to replace the sensor like have it done at home? Is there any guide or instruction that I can follow? Also, where can I get a new one? Thanks,

Reply to
vannie402 via CarKB.com

Thanks for the link Jeff !

Reply to
Phil

Check your basic electrical system. Battery should be at about 12V with car off and around 14V with it running. If the battery and/or alternator are failing, replace them.

-- Christian

Reply to
CMM

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