Transmission problems

Tiny
RAIDTHECITY
  • MEMBER
  • 2003 SATURN ION
  • 4 CYL
  • FWD
  • AUTOMATIC
  • 137,000 MILES
Hi everyone, I need help with my car. I currently bought it second hand about a couple of weeks ago and I currently am having some weird issues. It starts to jerk for some reason at the speed of twenty five to thirty five. I asked my mechanic what the problem was and he said it was the transmission, but did not specifically what in the transmission is the problem. I really need help guys! This has been such a pain in the head and I am so scared that I might stop in the middle of the road or get into an accident all of a sudden.
Friday, April 7th, 2017 AT 6:11 PM

6 Replies

Tiny
CARADIODOC
  • MECHANIC
  • 33,870 POSTS
When the problem is occurring, hold the accelerator pedal perfectly steady, then with your left foot, lightly tap the brake pedal. If that makes the problem stop for one or two seconds, it is likely a shudder from the torque converter. The additional clue is it will not act up for the first mile or two when the engine is still cold.
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Friday, April 7th, 2017 AT 6:27 PM
Tiny
RAIDTHECITY
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  • 3 POSTS
Nothing happened when I tried that. I went to go check it with an OBD scanner and it said that there was no problem with my transmission, just that my oxygen sensor needs to get changed. I don't know how is that related to the car jerk?
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Saturday, April 22nd, 2017 AT 10:57 AM
Tiny
SATURNTECH9
  • MECHANIC
  • 30,869 POSTS
It isn't related to the transmission what so ever do you have the quad coupe model by chance?
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Saturday, April 22nd, 2017 AT 11:55 AM
Tiny
RAIDTHECITY
  • MEMBER
  • 3 POSTS
It's a Saturn ion 2, 4-door sedan 2003
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Saturday, April 22nd, 2017 AT 2:11 PM
Tiny
CARADIODOC
  • MECHANIC
  • 33,870 POSTS
There's two misconceptions that must be cleared up. The cause of the jerking you asked about is very often caused by the use of the wrong transmission fluid that is missing a critical additive. I was trying to get you to verify that by tapping the brake pedal. This shudder always occurs at the lower speeds where the torque converter starts to lock up to provide improved fuel mileage. That is the range of speeds you listed. Tapping the brake pedal initiates an "unlock" command in preparation for the computer thinking you're coming to a stop. When you continue driving after releasing the brake pedal, the lock-up occurs again about two seconds later, then the shudder resumes. The additional clue is this doesn't occur at higher speeds when the torque converter is fully locked up.

The second misconception has to do with the oxygen sensor diagnostic fault code. That code did not say to replace the sensor or that it is bad. Fault codes never say to replace a part. They only indicate the circuit or system that needs further diagnosis, or the unacceptable operating condition. When a part is referenced in a fault code, it is actually the cause of that code about half of the time. First we have to rule out wiring and connector terminal problems, and mechanical issues related to that part. There's dozens of fault codes related to oxygen sensors, and they mean very different things. We need to know the exact fault code number to know where to start the diagnosis.
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Saturday, April 22nd, 2017 AT 9:45 PM
Tiny
SATURNTECH9
  • MECHANIC
  • 30,869 POSTS
You could also have a engine miss fire not bad enough to set a code but cause jerking.
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Saturday, April 22nd, 2017 AT 10:07 PM

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