1998 Pontiac Bonneville transmission performance

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

6 Replies

JACOBANDNICKOLAS

MECHANIC
109,885 POSTS

Mike:
Is the trans fluid still clean?

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Thursday, September 2nd, 2010 AT 10:32 AM

MIKIEMO

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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

MIKIEMO

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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

JACOBANDNICKOLAS

MECHANIC
109,885 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

MIKIEMO

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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.