Slow to downshift from overdrive to third gear

Tiny
GSXRSQUID
  • MEMBER
  • 2001 BUICK LESABRE
  • 3.8L
  • V6
  • 2WD
  • AUTOMATIC
  • 116,000 MILES
Driving down the road in lightly hilly country. When it comes to a hill it stays in overdrive and the RPM drop to about 1,300 and the engine makes noise like it is lugging but should not be at 1,300 rpm. (Maybe a harmonic?) If you give it hard throttle it will kick down and lunge forward and then you have to back off right away. If you give it throttle it light throttle will slowly gain speed without downshifting. Normally when it does this I give it hard throttle to downshift and then back off. On cars before the TCM I would think that the kick down linkage was not adjusted properly.
Friday, February 15th, 2019 AT 11:32 AM

13 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good afternoon,

I would start by changing the fluid and the filter. It sounds like the valve body may have some dirt it is preventing the valve from moving when they are supposed to.

https://www.2carpros.com/articles/how-to-service-an-automatic-transmission

How long since you changed the fluid?

Roy
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Friday, February 15th, 2019 AT 1:23 PM
Tiny
GSXRSQUID
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It was replaced a couple months ago.
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Friday, February 15th, 2019 AT 4:33 PM
Tiny
ASEMASTER6371
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What was replaced? Please be as specific as possible.

Roy
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Friday, February 15th, 2019 AT 4:35 PM
Tiny
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They drained the fluid and replaced it with Dexron 6. Did not pressure flush it.
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Friday, February 15th, 2019 AT 4:37 PM
Tiny
ASEMASTER6371
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Thank you.

That was a couple months ago and this is now.

It still needs to be checked. Otherwise, if it is the transmission then it has an internal failure.

What about the throttle body?

Roy
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Friday, February 15th, 2019 AT 4:40 PM
Tiny
GSXRSQUID
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  • 7 POSTS
On the engine? Nothing to that. I replaced the mass air sensor today because I had a code (I use maxisys ms906 BT).
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Friday, February 15th, 2019 AT 5:49 PM
Tiny
ASEMASTER6371
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Code? What code? You never said anything about that.

Roy
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Friday, February 15th, 2019 AT 5:54 PM
Tiny
GSXRSQUID
  • MEMBER
  • 7 POSTS
This problem has been going on since we got the car last year. It had lots of small issues I have been addressing. Had to replace a coil and replaced the valve cover gaskets, spark plugs and transmission fluid. Wife drove it and said it was running rough. I ran a diagnostic and it said it had a mass air flow sensor code that then cleared itself. I just replaced the sensor. There have been no transmission codes at all on it.
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Friday, February 15th, 2019 AT 5:59 PM
Tiny
ASEMASTER6371
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Okay, code reads rarely identify bad parts just failed systems.

Hopefully, the light will stay out.

I would love to help but cannot without the code number.

Roy
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Friday, February 15th, 2019 AT 6:06 PM
Tiny
GSXRSQUID
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With the tablet I can monitor real time operation of the transmission. Rpm, shift points gear ratios all kinds of data that I can record, including throttle position. Transmission OSS and ISS, current gear, 1-2 and 3-4 solenoid position,
Is there anything in particular I should be looking for?
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Friday, February 15th, 2019 AT 6:16 PM
Tiny
ASEMASTER6371
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No. This is not an electronic issue, it is a mechanical issue. There are no codes for mechanical issues.

Roy
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Friday, February 15th, 2019 AT 6:18 PM
Tiny
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Okay thanks
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Friday, February 15th, 2019 AT 6:23 PM
Tiny
ASEMASTER6371
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Your welcome

Roy
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Friday, February 15th, 2019 AT 6:27 PM

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