2005 Ford Taurus Car jumps / jerks once upon 25-35mph when

TRUMAN861

MEMBER
2005 FORD TAURUS
6 CYL
FWD
AUTOMATIC
105,000 MILES

I will preface this with the fact that I have changed 2 of the 4 o2 sensors and the light is on telling me o2 problem. Im working on that.
I will also point out by the way that the transmission was rebuilt approx 4 months ago by a reputable transmission shop.

I have found that once the car warms up and I come to a stop for a stop sign or red light there is no problem slowing or stopping. Upon giving it gas for the green light, it makes a very noticible jump/jerk one time when you hit approx 25-35 mph. Doesnt do it any other time.
It really feels bad andlike something bad could be happening. Can anyone please help?

Also any help with changing the o2 sensors as per my other post is greatly appreciated
Thanks

5 Replies

MERLIN2021

MECHANIC
17,250 POSTS

25-35 could be the tranny needs an adjustment, at this speed the engine and tranny are at the last shift point. Can you post the O2 code(s) so I can help knowing what you know?

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Sunday, July 18th, 2010 AT 7:36 AM

TRUMAN861

MEMBER
24 POSTS

Okay, I've done about a total of 25mi driving today, couple small trips and one trip to and from the autoparts store (10mi one way). The engine was at its normal top temp and it did not jump / jerk once. Today it's been acting normal.
One thing I do want to say as a correction is that the jump / jerk happens when shifting to 2nd gear around 15-20mph as opposed to the earlier mph. Sorry.

Pulled the codes this afternoon. Standard P0430 catalyst efficiency below threshold bank 2. The remaining two o2 sensors are scheduled to be replaced this afternoon by a mechanic.
Could this jump / jerk be related to the o2 sensor problem?

Thanks

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Sunday, July 18th, 2010 AT 1:34 PM

MERLIN2021

MECHANIC
17,250 POSTS

It could, and if the transmission is new or the battery has been disconnected, it may be in relearn.

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Sunday, July 18th, 2010 AT 3:35 PM

TRUMAN861

MEMBER
24 POSTS

I did have the remaining 2 o2 sensors replaced. The car is running nice so far and will update if the problem continues.
I have noticed the mpg on the display center is lower than it normally is and seems to fluctuate more than it did. I guess this is the learning process. Is this automatic and does it last long? One other question, when I scanned the engine codes, would that have also given me any transmission codes or are they scanned somewhere else?

Thanks

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Sunday, July 18th, 2010 AT 11:13 PM

MERLIN2021