Car will jerk backwards when going at a good speed

Tiny
PIKEWN
  • MEMBER
  • 2003 FORD TAURUS
  • 3.0L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 170,000 MILES
Had a bad idle problem. Have had plugs, and wires replaced. Had to have oxygen sensors replaced. One day later got new code P0172 rich. Had Mass air sensor replaced, still got code then replaced the EGR valve. Idles perfect now, but new problem. Car will jerk backwards when going at a good speed and then letting off the gas.
Wednesday, May 7th, 2014 AT 4:59 PM

4 Replies

Tiny
CADIEMAN
  • MECHANIC
  • 3,544 POSTS
P0172 is set because one of the injectors is sticking and will to be replaced. You can tell which one it is because the plug turns black. It says it's in bank 1 so start by pulling the ones by the fire wall. Good luck Craig
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Wednesday, May 7th, 2014 AT 6:26 PM
Tiny
PIKEWN
  • MEMBER
  • 2 POSTS
After the Mass airflow sensor, the egr valve and DPFE were replaced the P0172 went away, now I have the jerk when letting of gas when traveling at any speed above 40mph. I had the transmission rebuilt in September, only has 10,000 since rebuilt, so I hope its not that again, was wondering if after all of this could it be that the computer needs to re-learn the EGR valve position or could it be the coil. The coil is the original I think. I bought the car used. All of this started the day after I had the O2 sensors replaced as there was first a code for that prior to the P00172 that I now longer have. The engine light is not on now.

Thanks
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Thursday, May 8th, 2014 AT 6:09 AM
Tiny
CADIEMAN
  • MECHANIC
  • 3,544 POSTS
You will need to check all motor and transmission mounts. They can cause this jerking problem.
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Thursday, May 8th, 2014 AT 8:07 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,052 POSTS
Hi,

If you experience a jerking or clunking when you let off the throttle, it could be a few things. First, there are bushings in the front end which may have excessive play. I attached a pic and circled a few components to check. See pic 1.

Next, check to make sure there are no issues or excessive play in the drive axle CV joints. See pic 2.

Also, check to make sure the rubber insulator mount for the transmission is in good condition and not broken. See pic 3.

Confirm the same for the engine mounts. See pic 4

Here are a few links you may find helpful:

https://www.2carpros.com/articles/how-a-motor-mount-works

https://www.2carpros.com/articles/replace-motor-mounts

https://www.2carpros.com/articles/symptoms-of-a-bad-cv-axle-joint

https://www.2carpros.com/articles/how-a-cv-joint-works

https://www.2carpros.com/articles/replace-cv-axle

https://www.2carpros.com/articles/lower-control-arm-bushing-replacement

Let me know if this helps or if you have other questions.

Take care,
Joe
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Thursday, April 2nd, 2020 AT 7:02 PM

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