722.6 Transmission Torque Converter Lock-up Strategy
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Joined: Sep 2009
Posts: 107
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From: Chicago
'06 SL65
722.6 Transmission Torque Converter Lock-up Strategy
All,
I've been chasing a squeal/hum under hard acceleration. I think it could either be the converter or the the pump. Before the holidays, the roads were clean, i decided to hook the SDS and go for a ride.
While watching the Torque converter (TC) lockup pid, I noticed that the converter never goes into full-lock-up. it sits in either open or partial-lock. Does anyone know what the parameters need to be for the TC to go full-lock? the car doesn't have any codes. But, something is definitely wrong with this squeal/hum. I don't want to tear the Trans out of the car before I'm confident I've found the problem.
Also noted during test drives: Engine RPM can be seen to fluctuate 25-75 RPM on the tach while holding cruise control on at highway speeds. If anyone thinks I should post this in another forum, please come forth.
Happy New Year everyone. May 2016 bring us all good health and good times..
-P
I've been chasing a squeal/hum under hard acceleration. I think it could either be the converter or the the pump. Before the holidays, the roads were clean, i decided to hook the SDS and go for a ride.
While watching the Torque converter (TC) lockup pid, I noticed that the converter never goes into full-lock-up. it sits in either open or partial-lock. Does anyone know what the parameters need to be for the TC to go full-lock? the car doesn't have any codes. But, something is definitely wrong with this squeal/hum. I don't want to tear the Trans out of the car before I'm confident I've found the problem.
Also noted during test drives: Engine RPM can be seen to fluctuate 25-75 RPM on the tach while holding cruise control on at highway speeds. If anyone thinks I should post this in another forum, please come forth.
Happy New Year everyone. May 2016 bring us all good health and good times..
-P
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Joined: Nov 2010
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From: Welwyn, Herts, UK
2006 S600
High speed, high gear, low throttle and fully warmed-up transmission fluid.
I never found very much specific information about the TCC. All I know for sure is that it never locks up in first gear.
Nick
I never found very much specific information about the TCC. All I know for sure is that it never locks up in first gear.
Nick
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Member
Joined: Sep 2009
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From: Chicago
'06 SL65
Wish I could find more information on WIS on this...
MBWorld Fanatic!
Joined: Nov 2010
Posts: 2,605
Likes: 343
From: Welwyn, Herts, UK
2006 S600
Yes there are a few TCC fault codes:
P0700: Command Valve Stuck In Pressure Position, or TCC Stuck ON
P0740: Torque Converter Clutch Slipping
P0743: TCC (PWM) Solenoid Circuit
Nick
P0700: Command Valve Stuck In Pressure Position, or TCC Stuck ON
P0740: Torque Converter Clutch Slipping
P0743: TCC (PWM) Solenoid Circuit
Nick
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'06 SL65
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W215 CL65
I had the exact same noise on my car. On hard acceleration made a loud hum or whine sound (to an unsuspecting person would be turbo noise etc). Only when on hard acceleration. Removed tranny and replaced main transmission oil pump at front. Noise is gone.
Take a look at the pump and its failure, if left too long it can ruin the front converter case as it starts to eat into the casing (the gears in the pump). Mine had started to heat spot slightly but I caught in time to not have to replace the converter case.
Also, the old style pump uses a copper bearing, and the new style uses needle bearings.
Hope this helps
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From: Chicago
'06 SL65
Thanks for the heads up. I just don't like taking things apart under exploratory basis. Hopefully one of these days I'll get some time to mess around with it more.
I'd like to Connect a pressure gauge and see what the line pressure is going to the converter. I still think it's not going into full lock-up.
I'd like to Connect a pressure gauge and see what the line pressure is going to the converter. I still think it's not going into full lock-up.
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From: Germany
SL65 R230
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From: Chicago
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