Has anyone tried advancing the TPS slightly? It helps a buttload on the FI-ed SV-650, I was wondering if anyone's tried it on the FJR. I didn't find anything with a search.
The
Throttle Position Sensor sends a voltage to the ECU that changes with the mechanical movement of the throttle plates. The ECU converts the voltage to indicate throttle opening as a percentage. At idle the diAG screen will show 16-17 indicating that the throttle plates are open 16% to 17%, the amount necessary to flow enough air for the engine to idle at 1,100 rpm (give or take a few rpm). When the throttle is pinned open the diAG will read 99-100 indicating that the throttle plates are mechanically 99% to 100% open. The span of the TPS is fixed, you can't adjust the distance between 17% to 100%. The range is adjustable, if you drop the lower number to something like 14% the top reading will drop to 97%. If you raise the lower number to 20% then the top reading will be 103%. If I were to make a pretty sure bet, I would bet that the ECU disregards anything over 100% and simply sees it as 100%. The throttle opening percentage and especially the rate of position change are two important elements in the ECU determining the fuel injection trim. Which is a whole lot of words to say that advancing the TPS slightly probably won't help around idle and may hurt top end performance.
As to the opening post in this thread, the following is excerpted from something I wrote a while back. Because it was from a different issue this text may not follow this thread exactly but it does talk about the various reasons the '06 may have abrupt throttle issues.
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The '06/'07 share the eccentric throttle pulley that causes the rate of RPM change to be non-linear, which is fixed by a G2 throttle tube. The '06/'07 were included in the ECU recall for altitude drivability issues. The '06 instrument panels on some early bikes were recalled for an instant MPG readout stuck at 17 mpg.
Separate from the non-linear throttle response is abrupt power delivery. Some bikes are worse than others, some riders are more sensitive than others. This is remediated for sure with a PCIII. Some people claim that changing the CO setting helped them. Search out the Barbarian Jumper that enables the CO settings to be adjusted.
No FJR has to have any of these modifications done or parts added, but when required the G2 throttle tube, a PCIII and perhaps unwinding the throttle spring one turn are sure fixes.
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Surging: At a steady throttle, light engine load, the engine speed varies a small amount which feels like the throttle is being opened and closed a tiny amount even though it is being held steady. Sometimes fixed by CO adjustments, fixed with a PCIII.
Abrupt power delivery: When the throttle is closed the engine goes into a decel FI routine where fuel injection is basically turned off, then when power is asked for again there may be small hesitation without response as the throttle is rolled on, then suddenly you get all the throttle that you dialed up. Helped/fixed by a PCIII
Abrupt Throttle Response II: The Gen II throttle cam is eccentric (not round) causing the throttle to respond in greater proportion than what the operator intended. The steep ramp of the throttle cam is right around the 3k rpm range. A second issue are the gorilla springs on the throttle pulley making it very tiring to use and makes fine throttle control difficult. A G2 throttle tube & cam will neutralize the eccentric throttle cam. Some people acknowledge the risks and partially unwind the throttle springs to lighten up response.
Drive line lash: Free play between the engine output shaft and the rear wheel. With the bike on the center stand, engine off, in gear, rotate the rear wheel and note how much free rotation it has. This could possibly cause the same feel as abrupt power delivery and/or surging. No fix, not proven to be an issue.
Altitude sickness: Total lack of throttle response, bogging, very poor drivability. Often initiated by rapid altitude change, often reset back to normal operation by cycling the key off/on. ECU recall.
