1998 Pontiac Bonneville transmission performance

Tiny
MIKIEMO
  • MEMBER
  • 1998 PONTIAC BONNEVILLE
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 182,000 MILES
I have a 1998 bonnieville non turbo. When you drive in town and go to turn at intersection the car acts like it doesnt shift all the way down into first. And the shifts hard. It does not do it all the time just on occasion and is annoying. If you pull over and turn car off it seems to fix the problem and it does fine then. It does not do it everyday. I changed the trans filter and fluid. The old fluid was dark and smelt burnt. After cahmging fluid the car ran and drove like a dream for three days and not has started doing it again. What is wrong with it. Mike
Thursday, September 2nd, 2010 AT 9:28 AM

6 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Mike:
Is the trans fluid still clean?
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Thursday, September 2nd, 2010 AT 10:32 AM
Tiny
MIKIEMO
  • MEMBER
  • 4 POSTS
Yes for the most part. But we were told by a mechanic not to flush the tranny that it would cause problems.
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Thursday, September 2nd, 2010 AT 10:36 AM
Tiny
MIKIEMO
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  • 4 POSTS
I didnt flush the transmission. Just drained fluid and changed filter. So I know there was still some of the old fluid in the torque converter. Please help.
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Thursday, September 2nd, 2010 AT 10:46 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
If the fluid was really burnt and dirty, it can cause the trans to slip if you replace it all. New fluid has a detergent in it and will clean everything off the clutch plates. If they are burnt or bad, it could cause a slip.

As far as no downshifting, there are some electrical components that could cause the problem. Has the check engine light ever come on?
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Thursday, September 2nd, 2010 AT 11:25 AM
Tiny
MIKIEMO
  • MEMBER
  • 4 POSTS
Yes the check engine light will come on as it starts to act up. My step son put it on diagnostic check and it said trans filter. The trans mission does not slip.
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Thursday, September 2nd, 2010 AT 12:20 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
THe only thing I can think of is the pressure is low. If it worked when you first did it, it may need it again.
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Thursday, September 2nd, 2010 AT 1:43 PM

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