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  #1  
Old 11-20-2004, 03:41 PM
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Join Date: Aug 2004
Location: Scotland
Posts: 11
W140 Reluctant to upshift

Experienced a strange problem today. My S320 (W140) suddenly became very reluctant to upshift. Had to increase revs to over 4000rpm then release throttle before it would change up gear. Now I know it has a system that holds onto each gear until 3000rpm when the engine is cold until it gets above a certain temperature. However the engine was already warmed up, +80 degrees C although it was around 1 degrees C air temp.
After I had stopped and restarted a couple of hours later it ran fine.

What controls the upshift points of the gearbox - it is a 5sp auto non electronic gearbox (722.5)?
Is there anything that might require adjustment / cleaning etc?

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  #2  
Old 11-20-2004, 05:29 PM
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Join Date: Mar 2004
Location: Phoenix, AZ
Posts: 114
Well, I don't think this is good news...

This is the same symptom that my tranny developed right before near total failure. Mine started "flaring over" second, but was running fine (and shifting fine) otherwise - this went on for almost 10k miles, and then it developed the "not wanting to upshift" problem, and soon thereafter it started finding false nuetrals.

There might be some "easy" fix for this, but I think you will find it is an internal tranny problem (probably similar to mine - main basket not functioning properly, locking up planetary gears and making it tough to choose gears).

If you need a rebuild, I did LOTS of shopping before I got mine done - so I would be happy to give guidance or answers questions about finding a shop/mechanic to do the work.

-David
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  #3  
Old 11-21-2004, 11:52 AM
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Join Date: Aug 2004
Location: Scotland
Posts: 11
I hope that is not the case!

The car ran perfectly today, shifting gears when expected. The episode yesterday where it would not upshift until above 4000rpm seems to me to be more likely a faulty sensor, electrical/vacuum connection.

Does anyone know how the 'warmup' feature, that holds onto each gear to 3000rpm until the engine reaches a certain temperature, works?

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