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Discussion Starter · #1 ·
Hi folks,
I have a question about the torque converter on my 2002 540i. As I understand, from searching and reading this forum, I have a torque converter that is capable of locking in 5th (and possibly 4th?) gear. However, I'm not confident that it is doing so.

In previous cars that I've owned with a lockup TC, it's been fairly obvious when it's locked or unlocked (slight acceleration will not cause a change in engine speed that isn't matched by a change in road speed when locked), but in my 540, I just can't tell so far. Sometimes when I do that 'test', I'll see the tach fluctuate slightly more than I'd expect (i.e. before a change in road speed) and sometimes I don't... Maybe it just unlocks even under very light acceleration? Seems to me that, to do it's job well, it wouldn't unlock under the kinds of accelerative loads it would normally encounter through cruise control induced speed corrections (climbing freeway overpasses, etc).

For reference, I've gotten on the freeway, maintained a constant speed (~75mph?), and switched from 'normal' auto to 'sport' mode to 'manual' (5th gear), and back to 'normal' auto, and seen NO change in engine speed... not even a blip. So, whatever state the TC is in, I don't think it changes when I do that... so, either the TC stays locked through all modes, or is unlocked through all modes. Further, it appears that what I read in another thread about the tranny not shifting to 5th when in 'sport' mode until very high speed (like, beyond redline territory for 4th gear) is not true for my model - it indicated "5" when I hit 'manual', and the engine RPMs never changed.

Any input? Suggestions for testing, what to look for? I'm not really having any problems with it, just being (overly?) concerned about my new-to-me baby.

I'm getting about 24-26 mpg @ 70-80mph (based on the OBC, after a consum1 reset) if that means anything to anyone... It's all new to me, but that seems reasonable for that speed and this engine with everything working right.

If it would help, I'd be happy to follow up with some speed/rpm figures for folks to compare to.
 

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I'll admit that I've never heard of such a thing but then again, my 530i is a manuel. :)
 

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Discussion Starter · #3 ·
Ågent99 said:
I'll admit that I've never heard of such a thing but then again, my 530i is a manuel. :)
Yeah... Hopefully, your 'torque converter' locks up every time you lift your left foot off the pedal! :rofl:
 

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Ågent99 said:
I'll admit that I've never heard of such a thing but then again, my 530i is a manuel. :)
Ah, Manuel....I knew him well. (Sorry, couldn't resist.) :rofl:
 
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