Turn the key off, wait a few seconds, then turn the key back on.

 

BC is part of te cluster reset.

 

For those that say computer reset makes no performance change. The computer reset thing has been something I as a new 2003 Mini Cooper S owner have found interesting. I have also had conversations with tuners about this topic. So here is something that seems to pass by those that claim that it has no performance value. If I am wrong I look forward to comments.

I noted that 002 who seems to be very knowledgeable about Mini's when talking back in 2005 about octane and computer resets indicated:
"The car is tuned to run 91+ octane. If you go ahead and run 87, it will knock then retard the timing until it stops. once it finds a good spot it will "adapt" by remembering to use X timing at Y temperature at Z rpm at B load. So it's knock adaptation would be X from the base map.

Same with fuel. It starts at a base map and makes adjustments from there. It monitors the 02 sensors and adjusts the mixture. this change is assigned a number that reperesents a delta change.

Adaptations only work within a range and are meant to allow the engine to run well even though there are "worn" parts or manufacturing variances."

So if someone has been running bad gas or had some part that is worn and the system has had to make adjustments to compensate and if a worn part is the issue you fix the worn/bad part or if bad gas or wrong octane is the issue you start using better gas then you reset the computer the car should perform better. Since the car as made changes though they may be specific to some throttle position, load, etc.. if that combination is used often enough then when the change happens after reset it should be noticable (seat of the pants) and if the issue is fixed then performance should increase not cause poor performance.

Just some thinking from a new guy.

 

First, welcome to NAM, and I hope you're having a blast with your MINI!

Your post is pretty much spot-on, and the MINI does have an adaptive ECU - BMW even describes it as such in several documents. The disagreement is only regarding the time frame over which these adaptations take place.

Some people believe that when you change parts or fuel grade, you should reset the ECU in order to "overcome" the thousands of miles driven under the "old" conditions and give the ECU a "fresh start".

Other people (myself included) believe that the ECU will adapt to the new parts/fuel/weather/etcetera in a matter of seconds or minutes, so no ECU reset is needed - just drive the car, and the computer will quickly realize that new optimum settings are required and will make those changes.

Think of it as getting dressed in the morning. You choose your clothes based on the temperature, humidity, whether or not it's raining, blowing sand and dust, snowing, etcetera. In making your decision, you don't need to consider what the weather was like last month or last year, you just look at what the conditions are *today* and base your choices on that. Even if you dress for yesterday's weather and you find out today's weather is vastly different, you can change your entire outfit in a few minutes.

The ECU is the same way. In the case of fuel octane, the short-term fuel trim maps in the ECU update almost instantaneously, and even the "long-term" fuel trim maps update in a matter of minutes. This has been confirmed by people monitoring the fuel trims while doing dyno runs.

But of course, do whatever you're comfortable with. Even if I'm completely right, you have nothing to lose by doing an ECU reset except the time it takes to perform the reset and to set the car's clock afterward.

 

Thanks for the reply.