{EDIT/June 17, 2014:
The results of this thread are condensed and posted in Frequently Asked Questions under the thread TPS Setup and Throttle Balance Tuning.}
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Over on the Oil Filters and Oil thread a discussion of the TPS was raised. I think it worth bringing it out for further discussion:
Pete said, "The TPS sits on top of the throttle butterfly shaft. If you increase the idle by using the throttle stop screw what you are doing is opening the butterfly. As you open the butterfly you move the TPS so that its reading changes.
Setting everything up is a real juggling act. First you set the TPS with the bleed screws closed or nearly closed and if the idle is too low after this you have to increase it with the throttle stop screw. Then you have to re-set the TPS. When you've done this you will probably be able to adjust the idle speed to where it should be without missing or hunting by using the bleed screws. If it misses and hunts though you have to adjust the speed up or down again with the stop screws, re-set the TPS again and then fiddle with the bleeds again. Eventually it will all come good, you'll get a steady idle, the correct TPS setting and good fueling all the way through, (As long as the TB's are ballanced!)
Don't try to think of it as *magic* it's not. This is one of the major problems is that people are CONVINCED this stuff is difficult, it's not. All you have to do is THINK about what is happening with the throttle butterflies and the TPS, (Which is a simple potentiometer/rheostat.) and it all becomes clear. Then use LOGIC to see what you are doing and it will all fall into place!
Oh and re-reading this I should point out that we aren't talking about altering the fuel map here, that opens another whole kettle of worms. all you are doing by setting things up this way is optimising the available map. In fact you may not even be doing that! Don't be afraid to experiment. If you find it pings its head off with the TPS set at 150Mv? Well, try another reading and see if that helps! You aren't going to destroy your motor on short test runs. If it still runs like a munter and the plugs are white then you will probably destroy stuff if you choose to ride across West Texas at WFO but as long as you are remotely sensitive that won't happen!
While you can get a lot *more* out of the 15M equipped bikes by employing a PCIII, Tuneboy or one of Cliff's units I urge people to actually get the stock system set up well first before going to all the extra hassle and expense. This isn't to say that these products don't work or even don't have a very good place in the overall scheme of things, simply that before you try these alternatives get the original system set up well. THEN when you get bored of how nice it is, THEN you can start looking at the serious hot-ups!"
Pete Then Dlaing added,
"And use common sense and at least partially understand what is happening.
A higher TPS reading will almost always mean it will give it more fuel.
So, if fuel consumption is terrible and engine feels sluggish and the people riding behind you are passing out from the fumes, your TPS is probably set too high.
If engine is pinging and spark plugs are the color of grey ash, your TPS is probably set too low.
I would not recommend going outside of the recommend range by more than 50mV.
Although if you do and it runs like crud, just reset it and as Pete suggests I suppose no harm is done if you only rode around the block a few times.
I permanently installed test wires so I can test frequently.
It sure can go off a bit before noticing.
IMHO the time to be retentive about TPS setting is after you spent money on a custom map that you of course did a proper tune up prior to the dyno session.
Noting the TPS at that time and resetting it forever after at that number (±10mV or so...) will give you a happy bike.
People with no tuning software and aftermarket mufflers can certainly benefit from a few additional millivolts." Ryland:
"So the bottom line for TPS is 150 mv (even though others have said the target is 150 mv at fully closed) at an idle speed of 1100 to 1200 with vacuum balanced?" Dlaing responds:
"The term "fully closed" can be misleading.
Fully closed with linkage disconnected and set screws backed out and choke not interfering, the TPS should read 150mV ±15mV.
Idle should then be set to BOTH the recommended RPM and idle TPS reading(around 500mV not around 150mV).
Getting it to do both may require a compromise.
The idea is to get the idle to match the recommended RPM and TPS mV without touching the TPS adjuster, since you already set it to 150mV fully closed, etc.
The recommended settings vary but are in the range of 1000-1200RPM and ~485-550mV at idle.
Most people don't have the tools to set CO.
Once TPS is set, and ignoring CO, doh.gif I think optimization is best done with mapping software, but if you don't have mapping software, twiddling with TPS adjuster at idle may have benefits, just make sensible changes.
Also, note that TPS changes by about 10-20mV depending on whether engine is running or not. I favor the engine not running method, but to each their own." And GuzziJack clarifies:
"150mv is the reading that the TPS should give with the throttle butterfly FULLY closed i.e. with idle screw backed out and all linkages/cables disconnected. At 1100/1200 rpm idle you should then find that the TPS reading will be in the low 500mv range."
I hope this format is acceptable to base the discussion in a dedicated thread.
I'm not disputing any of the valuable postings shown above, yet I believe there are a couple simple nuances that enhance the final result.
If you have set the closed value and idle value appears low check a couple things:
[edit/ Nov 2020] First, the TPS indexes the throttle plate opening to the map in the ECU. Setting the TPS to 157mV (per Meinolf's careful investigation) with the plate completely closed indexes the map correctly.
Second, If you set your idle based on the tach it is a good bet that you are idling too low. Based on the Axone equipment I know of several V11 that the tach is 300 rpm high. No big deal perhaps at 4500 rpm, but there is a huge difference if your idle is indicated 1100-1200, but the motor is actually ticking over at 800-900. Use the TPS setting to bring the idle mV to 500 (466-521).Again, I'm finding higher in the range gives a better result. Use the air Bypass Screws to balance the Throttle Bodies at idle and get your final tickover. Don't be surprised if the tach reads 1300-1400.
Ride well, docc + =
