Originally Posted by
Tork
Evade - As mentioned in my post, when backing out the idle and snapping the throttle you're not trying to reach a degree reading of '0' (zero) and need to completely ignore the actual numeric value displayed.
1. You slowly back out the idle while observing a decrease in the degree value as the throttle plate closes. At some point, it will stop decreasing in value. It may or may not stop at zero. Doesn't matter. Again, ignore what the actual number is, it's irrelevant. At this point, the throttle plate is theoretically closed, but it may be still be hanging open slightly due to debris or throttle cable friction.
2. Back out the idle another 1/2 turn and snap the throttle. If the degree value continues lowering further after snapping the throttle, back out the idle another 1/2 turn and repeat until the degree value ceases to lower any further. Now hit reset.
The reason why you need to completely ignore the TPS degree value during the reset procedure is that you must assume the possibility that the TPS zero is currently mis-calibrated. Therefore, if you are backing out your idle and stopping at a mis-calibrated '0' (zero) indicated value and hitting reset, and the throttle plate is still slightly open for whatever reason, the end result will again be mis-calibrated and the error will be subsequently factored into your ECM mapping calculations.
If your displayed degree value ends up at '0' (zero) after backing out the idle and snapping the throttle, it's a good indication that the previous TPS reset calibration was done correctly. If it ends up going lower than '0', that's a good sign the TPS is out of calibration (mechanical sensor wear or the previous reset procedure wasn't done correctly). In this case, your bike may actually run better after you've completed the reset since the calibration was previously off.
Another TPS-related tip: Always make sure you're throttle cables are adjusted properly, to include a tiny bit of slack per the manual instructions. That slack allows the throttle plate to correctly return to it's mechanical stop with no throttle applied, especially when the handle bars are at their extreme left/right limits. I worked on a friend's XB that had just come from the shop after a minor low-side accident. The mechanic had adjusted the throttle cables and reset the TPS among other things. Unfortunately, the throttle cables were adjusted too tightly and had no slack at all. The mis-adjusted throttle cables were constantly pulling enough to keep the throttle plate slightly open, even after backing out the idle adjustment and snapping the throttle, resulting in a TPS reset calibration that was completely off and made the bike run like crap (poor idle, coughing, backfire through the intake, cutting out under load, etc.). While looking at the bike, I noticed the absence of that little bit of play you always feel in the throttle grip, and the idle RPMs would increase when you turned the bars left and right. After re-adjusting his cables and resetting the TPS, the symptoms were cured and the bike ran great.
