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Zedbra has my analysis of the problem. If the twist grip seems to stick and then suddenly break free with extra effort, replacement is about the only option. For Daves31, the only "fix" I am aware of for that vintage is for the tendency for the idle to reset without the rider understanding why. Many have experienced a high idle after start and would have to reset the computer. The suspected cause was twisting the grip slightly forward at shut down, usually caused by holding the front brake while switching off the ignition. . Enough people had trouble with this that Harley did a programing change to the ECU under warranty Before the fix, the ECU would assume the twist grip was at idle at shutdown and record that position for the next start. If the twist grip had been twisted forward slightly, it would spring back when released and command a higher rpm at the next start.. With the run switch on, cycling the ignition ON and OFF 4 times, slowly enough for the engine light to go out each time, while NOT TOUCHING the twist grip would reset the ECU reference point for idle.
The throttle sensor output is linear and you cannot change that. There is nothing you can plug in between the sensor and the ECU to change that. The way the engine or vehicle, whether a car or a motorcycle, responds is based on many factors. The engine configuration determines the power curve. Gearing in the vehicle is another factor.
I don't know if the sensor in your grip is Hall-Effect or contact. I was under the impression that Harley went from cable to Hall Effect throttle by wire.
actually vance and hines used to make a product called throttle pak...it was designed for these early tbw bikes. Mine was was very sensitive at part throttle openings. I got the tbrottle pak first and it really helped it. Then I got a full dyno tune and that got rid if the built in lag that was built into these bikes...guess they thought we couldn't handle all 65 hp at once lol. So yes your problem is real and yes there is help
BTW, although the input to the ECU from the throttle sensor is linear, most tuners can change the linearity of the throttle position. It is very common to more response with less position. For example from 0 to 25% represents 0 to 50%.
Last edited by TriGeezer; Apr 23, 2020 at 12:06 PM.
"the Hall-effect sensor 146 is configured to output a voltage proportional to the sensor's movement or orientation in a magnetic field. "
The patent is long on description but there are a pair of hall-effect receivers in the sensor and when it was originally designed, they use a pair of Micronas Model No. HAL815 receivers. These are programmed so as to use two data points and the signal has to be linear. Typically, the two data points are idle and wide open throttle.
There are six wires to provide two isolated signals to double check each other. You cannot change the slope of the signal by plugging something into the wire. Once the sensor is programmed, it cannot be changed. This is not 1970 technology. The ECU takes the signal and if you wish, you can program the ECU to interpret the signal differently.
The auto industry has used the same technology for many years.
Last edited by jimglassford; Apr 23, 2020 at 12:53 PM.
Reason: Spelling Errors and Title Improvement
Dont know what it has to do with anything but when I bought my 09 Ultra Classic it had Perfomance Machine grips on it. Had to turn the throttle quite a bit for it to do anything & it was annoying. I changed them out to Iso-grips & now it's smooth as silk. Have no idea why it was better after switching them...
The reason why you and most people do not like the feel of the throttle is that you are just controlling the compression of a spring. In the old days of cables and linkages, the force required to open a throttle was higher than the force to all the throttle to close. This is called hysteresis. Your brain uses this difference in force as one of the cues to control position. Higher end electronic throttles used in large trucks and construction vehicles use a mechanical device to add this feel again. However, as I said earlier, your car uses the same throttle by wire technology so you are just pushing a spring under your foot. As for the technology itself, it makes the vehicles run much smoother, start easier, create more horsepower and get better mileage.
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