97 LeSabre Transmission Hunting

[dpalomaki]

97 LeSabre Limited, 107,000 miles. Occasionally get hunting between 3rd and 4th under the following circumstances. Speed between 45 and 65 mph, light but steady steady accelerator setting, on slight upgrade, with system warmed up. Depressiing or letting up on the accelerator will cause the hunting to stop. Is more common in summer than winter. During the hunting, the tach indication switches between around 1600 and 2200 RPM. During the hunting it changes gears every half second or so, No indication on the Service Engine Soon light. Does this often enough to be distracting over the laast 30k miles or so, but not always and not when I want it to for diagnostic purposes..

Any ideas what might be causing it and a soplution?

[Crang]

Hello,

I have seen this before on the same year model. You think it's a gear problem when in fact it's most likely the torque lockup clutch. It's like a continous thump. Either the control module or the clutch is gone on you. You can disconnect the solenoid but the lockup would never kick in.

I can grab the manual and tell you more if you would like.

[dpalomaki]

Thanks for the note. I do not feel/hear a thump or thumps as such. Because it only happens some times, and the tachometer RMP ratios correspond to 3 and 4th gear, I suspect it is actually rapid shifting between 3rd and 4th. I hope to get a scanner on it to track the PCM commands to see if the PCM is sending inappropriate commands, if I can get it to do the rabid shifting on local roads this weekend

If you have something from a transmission manual, that might help. The basic service manual does not address hunting, jsut shudder, which this is not.

[Crang]

I have the dealer manuals for a 92 and the Mitchell on demand for any car.

Also try and turn off the overdrive (you could call it 4th gear) and see if it still happens. If it does, then it's the lockup clutch. On those cars the D in a circle is the overdrive and the plain D will go as high as 3rd gear.