Living in New England, with winter coming on, I decided to bring it to the dealer to get this problem resolved. Since I am at just over 12k miles (on a 2002, of which I put on about 8k this year!) I decided to spring for the Motronic test (which I think is called the GS-911). My local dealer (Second Wind BMW, Merrimack NH
) quoted me a price of about $50 to perform the test.
So, despite the sub 40 degree weather, I rode it in on Tuesday for the test. Well, to my surprise, it did report a fault, with the throttle potentiometer (I still have no idea what that actually does!). The dealer said they could resolve it with another hour of labor, so I said what the hell. Anyway, we are back to perfection with this "simple" adjustment (I peeked in and saw that the gas tank was off, both upper fairings, and God know what else).
Although it took well over 2.5 hours, the dealer charged me only for 1.5 hours and gave me a 20% "winter discount" for a total dent to my wallet of just over $100. They didn't even "razz" me when I told them I do most of the work myself (including the HID upgrade). They also told me that it was unlikely that I had caused the failure with my HID effort. I am still skeptical, since my mileage dropped from about 44mpg to 39mpg (actual, not BC) and the idle started acting up exactly at the time of the HID upgrade.
So, I still think I probably caused it (presumably by not being careful with the battery as I removed it, causing sparks at the positive terminal). However, as the master tech explained it to me, the throttle potentiometer seems to be a mechanical device, not an electronic one.
The other thing I learned is that I am very perceptive about the performance of my beauty aka "Dragonfly". I knew instantly that something was amiss, even though the performance did not seem to suffer. I was sure that the tone of the engine had changed, and now that it is back to perfect, I know I was right!
Can anyone explain this component (throttle potentiometer) to me?
And I still have yet to learn the hazards of overfilling the tank, and presumably fouling the "cannister".