| Author | Message | ||
     Motobear46 |
Hello, I haven't read any thing about the TPS other than how to set it and when it's required to do so. But what does it do? Does it change the amount of fuel delivered at a particular point of rotation of the throttle grip? When you change to an aftermarket muffler, what changes occur that makes this sensor reset necessary. Is it somewhat like rejetting a carb for a non-fi bike, accomplishing the same end by a different means? I thought the race ECM is the equivalent to rejetting. Which still leaves the question, what does the TPS do? Thank you for any help Barry | ||
| Lorazepam |
The TPS is the throttle position sensor. It communicates with the ECM, letting it know where the throttle is located, either on or off, or somewhere in between. this allows the ECM to decide how much fuel to inject for each intake stroke. All the TPS does, is tell the ECM where the throttle is positioned. | ||
| Davo |
It is my understanding that there is a little wear or "slop" during the break in period that might create a small amount of intolerance that may effect the performance of the fuel injection system. | ||
| Nopork |
I reset mine on my recently purchased used Uly yesterday. What a difference. It pulls down low better then before and hardly any surging compared to before. Mine had about 2700 miles on it and idled really rough and had some surging around 2500-3000 rpms. Bought the software from Dave at Appleton hooked it up to my old lap-top and tuned away. Idles much much better, starts almost immediately cold or warm, and not anywhere as cold blooded as before. A whole different bike on the 150 mile route I took today. I think mine had been off since the previous owner had taken it to the dealer and tried to get it taken care but they must not have zeroed it out correctly or something, because now it runs as it should compared to before. The best couple of HD's spent in a long time. Thanks Chad and all for the TPS and AFV info. | ||
| Davo |
Nopork, Did your bike have any pre-ignition problems before the TPS reset? | ||
| Nopork |
No pre-ignition problems, just poor idling and surging at 2000 rpms and above in lower gears. The first owner had the timing sensor worked on before I bought the bike and said it was causing some ignition problems though. | ||
| Lovematt |
The TPS reset essentially connects the physical butterfly valve to the ECM electronics controlling the ignition and fuel injection. You set the physical position of the throttle at a certain point (fully closed off so it slightly "sticks" when opened up) and then use software through a cable connected to the bike to tell the sensor the throttle is completely closed (0 volts). As the throttle opens the voltage changes telling the computer and fuel injection where the throttle position is. Over time this "connection" changes because of the throttle cable sticking or wearing of the physical parts and so the sensor no longer correctly reads the throttle position (i.e. throttle might be closed but the sensor reads .3 volts or higher). As a result, the reference point is off and there is a delta between the two all time. That is why the TPS needs to be reset from time to time. Of course other things like static ignition timing, wires, injectors, plugs, etc. all need to be right as well. I bought the VDSTS kit from Al at American Sport Bike and it was well worth it...I can do the TPS reset at home at any time which is very convenient and is about the only thing I couldn't do at home other than major problems if they crop up. | ||
| Blake |
Completely closed throttle is not "0 volts". A TPS output of "0 volts" would be extremely problematic. Voltage output for fully closed throttle with idle screw backed full out should be around 0.5 V. Please see prior bloviating about TPS, it's function and related calibration of ECM in the Knowledge Vault at... http://www.badweatherbikers.com/cgibin/discus/show.cgi?tpc=3842&post=625527#POST 625527  (Message edited by blake on April 23, 2006) | ||
| Lovematt |
Oops...my bad...just referred to the instructions that came with the VDSTS and Blake is absolutely correct. Initially I was going to just say 'some voltage' as a reference point instead of throwing out a specific...guess I should have just stuck with that. | ||
| Thunderbox |
There isn't any need to do a TPS reset if you change your exhaust pipe. The setting is done with the engine off ignition on and no muffler would make a difference then. |
