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I own a 2000 BMW 528i with ~107,000 miles and have a question regarding the Steptronic transimssion. I have owned the car since it was new. Lately I’ve noticed the following:
1) Occasionally (not always), when I take off from a start that there is a very slight vibration as I accelerate. This seems to be only from around 0-30 mph and I would say between 2nd and 3rd gear. My wife uses the Sport mode of the transmission and shifts manually and does not experience this.
2) Unrelated to #1, while driving down the road at a comfortable speed, let’s say 40 mph, the transmission will shift down a gear or up a gear if I barely ease-off or ease-on the accelerator. I don’t remember this happening in the past so much. Again, my wife uses the Sport mode of the transmission and shifts manually and does not experience this. I could just use the Sport mode and avoid these issues but I wonder if this is only the beginning of problems? I should point out that I have not changed the tranmission fluid and plan to do that soon. What are your thoughts?
A
Well, number one ….. get that fluid and filter changed. Yes, it is possible that the issues you are experiencing could be related to secondary issues due to the old fluid. The Bentley repair manual covers the fluid and filter change. The Spring 2006 issue of our Fast Times newsletter contains a DIY article on changing the fluid and filter.
Filter kit:
Fluid:
Fluid pump:
Bentley repair manual:
Spring 2006 Fast Times:
The acceleration vibration could be due to a variety of potential issues. However, if you find that the vibration goes away if you reduce throttle (while accelerating and experiencing the vibration), I’ll initially assume that we may be dealing with a drivetrain issue. In this case, we could be looking at a worn flex disc (connects the transmission output flange to the driveshaft), driveshaft center bearing or driveshaft u-joint or rear CV joint (on the driveshaft). There is a slight possibility that the vibration could be coming from the transmission, but we won’t go there, just now. As for the odd shifting while at speed, let’s do some testing, in order to get a bit more detail. Accelerate at a moderate rate, while taking note of each up-shift. By the time you get to around 50-mph, or so, level off on the acceleration. In all, you should notice 4 up-shifts (1-2, 2-3, 3-4, 4-5). After the final up-shift, and once the speed is leveled and the throttle is reduced (compared to accelerating), you should noting one more drop in RPM (by about 200 to 400 RPM), which is the torque converter clutch locking up. Once the clutch is locked, if you give a very slight increase in throttle, the RPM should not change (just as if you had a manual transmission with a regular clutch). If you give a bit more throttle, the converter clutch should disengage and the RPM should go up by 200 to 400 RPM (do not give so much throttle that the trans actually downshifts from 5th to 4th), and in this mode, you can notice the RPM vary as you vary the throttle application slightly. Now ……. once you are familiar with the above points, get a good hold on exactly when and how the odd shifting is going on. What gears? What throttle load? What speed? Does it happen at one speed range, but not at a faster or slower speed? Is it actually just the converter locking & unlocking? ….. etc? In the Sport mode, the converter does not lock-up. Perhaps, you are experiencing the converter locking & unlocking and your wife does not get the issue because the converter never locks when in Sport mode. If this is the case, we can explore this further.
