2005 BMW Mini Cooper transmission issues, high RPM

Recently, Gordon B in our Ask a Mechanic forums wanted to know what could be causing his 2005 Cooper to have a "tight wind" in the transmission and be causing the engine to run at high RPM rates.

His Cooper has a continuously variable transmission (CVT) and I responded with these suggestions, after asking some questions about the vehicle's mileage and maintenance history:

This is a common problem with the first-gen Cooper. There's even a class action lawsuit over it. Continuously variable transmissions (CVT) is relatively new and in 2005 was pretty cutting edge for an entry-level car like the Mini.

These cars have "adaptive" learning, so a transmission computer reset may help. It's a first (and easy) step that's worth a shot.

Next, look at the fluid and at your maintenance interval. I think the first fluid change is at 30,000 miles. If you're well past that and getting to the next one, that may be it as well.

Early CVTs Have Issues

It's no news to experienced mechanics that the early CVT options that appeared in premium cars in the early 2000s are often plagued with problems at higher mileage. While today's CVTs have improved considerably, early adopters often paid the price with the first generation or two of this innovative (and fuel saving) transmission.

To kind of summarize how a CVT works, instead of having gears like a normal transmission does, a CVT has a sort of mesh of gearing options so that shifting from one gear to the next is no longer required. Instead, the transmission just adapts to the increased torque and speed of acceleration and deceleration.

Resetting the 'Adaptive Learning'

My first, and simplest, suggestion to Gordon was to reset the transmission - to remove anything it had "learned" through its computer. With the Cooper and many other vehicles that use CVT, the car "remembers" how it is usually driven and uses this information to do things like adjust the throttle control and fuel injection to better suit how the driver uses the car.

Sometimes, this "learning" can get out of whack and throw things off. So it requires a reboot, as it were, to start off fresh. This is accomplished by simply removing the battery cables from the battery, attaching them together, and making sure they do not touch the battery's terminals or any metal parts of the car. Leave them that way for 1/2 an hour or so, re-attach, and the car's computers should have "forgotten" all of the information they've stored.

This can fix the problem Gordon's Cooper is exhibiting, but may not.

Maintenance Intervals

Normally, manufacturers give recommended maintenance intervals for things like fuel filter changes, transmission fluid flush and replacement, etc. With a CVT, the interval for flush and replacement is critical because this transmission is much more reliant on its fluid for operation than are standard automatics.

The fluid in a CVT is used for both lubrication and operation, as pumps pressurize it internally and use it to make adjustments throughout the transmission. When the fluid no longer retains its proper viscosity and density, those things can stop working properly.

Fixing the Problem

Unfortunately, Gordon never returned to respond to queries about his car in order to further diagnose his problem. The issues he's having and that are common to early adoption of CVT are not easily repaired by the home mechanic anyway. Often, only a dealership can actually do the work and many of these vehicles have recalls and service requirements that their owners should be aware of.

So learn about your vehicle's needs, check those recall reports (they're easy to find online) and keep your CVT well-maintained.