Throttle Position Sensor

[docc]

{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
+ =

[Ryland3210]

Good idea, docc.

 

Here's another procedure from the How To section, which seems to be technically thorough. However, note that the "My comments" are my personal edits, for my own file.

 

I would like to see a response to these comments, and any superseding understanding of Jeff's comments with the result being a comprehensive, thorough, anc accurate procedure/explanation.

 

Jeff in Ohio, April 13, 2004

“How to Balance the Throttle Bodies, with pictures, even”, in the How To section

 

allow me to offer these comments. the air bleeds are not there to adjust the idle mixture, that is what the CO trimmer is for in the factory software. Idle Mixture Screw: This is located in the computer under the rubber plug, which is covered by the Moto Guzzi labeled decal. It's a tiny screw on a trim potentiometer; use an eyeglass screwdriver. The full range of adjustment is 270 degrees and clockwise is leaner, CCW is richer. The air bleeds are to be used for idle speed adjustments. A more proper procedure is to:

 

1. set TPS with everything backed off and disconnected (My comment: this means with the right throttle butterfly closed, idle screw, connecting rod and choke cam backed off) to the correct 150mv value

 

2. balance throttlebodies using the throttle stop screws with the air bleeds screwed in and the linkage unhooked so that the TPS reads the correct value as indicated in the service manual (3.4 deg +/- .2 deg, roughly 500-525mv) This is so the ECU is now set up so it knows the throttle plates are in the correct position for idle so all the mapping vs. throttle angle works out correctly. Your idle at this point will probably be be BELOW 1000 rpm and rather rough. (My comment: An alternative is to first balance the butterflies with the air bleeds screwed in, but then set the airbleeds to ½ turn open to raise the idle speed to 1100 RPM and check the TPS reading.)

 

3. open airbleeds and use them to balance to achieve the final appropriate idle speed of around 1100 rpm. Your idle should have smoothed out now. The factory manual goes out of its way to state the airbleed screws are there to set your idle speed. You will find that your airbleeds will end up being around 1/2 turn open as stated in the factory manual.

 

4. Adjust the linkage so that it can be reassembled without having to open one of the throttlebodies more than the other - that is, the socket on the link should drop back on the ball without having to move anything.

 

5. NOW rev your bike up and synch using the white knob. You might find that of you took great care in step 4, that the white knob has to be turned very little if any at all.

 

6. NOW use the factory software and a CO meter to set the correct idle mixture. In a pinch without a CO meter, you can set the trim like a mixture screw on a carb by adjusting it up and down to achieve the best quality of idle. That is why the software is needed - it is used to set the idle mix, NOT the airbleeds.

[John A]

I find it easier when setting the TPS for experimental tuning to do it at wide open throttle.The reading is always the same when you hit the stop.When you use the idle stop it floats around some depending how hard you push on it.Easier repeatability on the wide open stop. Theoretically the TPS should read at least 80% of the reference voltage [ 5 volts] at WOT. .01 volts makes a big difference on how it runs.If it's set too much when you ride it you will notice a slight acceleration when you slowly close the throttle.

[dlaing]

I find it easier when setting the TPS for experimental tuning to do it at wide open throttle.The reading is always the same when you hit the stop.When you use the idle stop it floats around some depending how hard you push on it.Easier repeatability on the wide open stop. Theoretically the TPS should read at least 80% of the reference voltage [ 5 volts] at WOT. .01 volts makes a big difference on how it runs.If it's set too much when you ride it you will notice a slight acceleration when you slowly close the throttle.

That sounds like a good idea.

I seem to recall I get about 485mV at WOT.

Do you do it with linkage disconnected?

If not, then you might get some bad readings if the left tops before the right.

Of course you can just back off the left and balance later.

EDIT Looking for a "how to set TPS" instruction? The following is a result of this thread:

http://www.v11lemans.com/forums/index.php?showtopic=12204

[John A]

Yea, I just popped the one link off. 485mv sounds about right but it's worth playing with as each engine seems a little different as an assembly.

[dlaing]

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.

The documentation on what the correct idle rpm and idle TPS mV varies a lot.

In my workshop manual it idle RPM should be 1000-1100, but I have seen higher numbers recommended.

I think Pete Roper recommended 1200RPM, which sounds good to me.

My workshop manual says in one place TPS at idle should be set to 3.2-3.4°

In another place in the workshop manual it says 3.1-4.1°

In a newer workshop manual, it says both 3.2-3.6° and 3.1-4.1°

On a 2002 California Stone these numbers correspond somewhere between about 466mV and 579mV extrapolated from this chart: http://www.mphcycles.com/Technical/tpsexcel3.htm

I always presumed the V11six speeds were the same, but Mr. Bean got a different conversion from Moto International and his software(technoresearch?) confirmed the difference. So for the V11 3.6° is about 485mV.

So at idle the mV might translate to between 430 and 540mV

It would be good to know how the Voltage and degrees relate, but not critical.

[BrianG]

Wouldn't it have been nice if Louigi had put the TPS on the left side throttle body?? Then you'd just set the closed TPS value, crank up the idle speed and balance the right throttle body into the mix and you'd be done!

 

Sounds like a winter project to me!

[Ryland3210]

That sounds like a good idea.

I seem to recall I get about 485mV at WOT.

Do you do it with linkage disconnected?

If not, then you might get some bad readings if the left tops before the right.

Of course you can just back off the left and balance later.

 

Do you really mean 4.85 volts at WOT?

[BrianG]

Do you really mean 4.85 volts at WOT?

Should be close..... it's a 5v reference system, and the TPS should vary the voltage signal from some designe"0" (apparently 150 mv) to near-system-reference...5v at WOT... in order to provide the fullest range of values to the ECU.

 

485 mv is typical idle voltage....

[dlaing]

Do you really mean 4.85 volts at WOT?

Oooops I made a mistake.

Should be 4850mV or 4.85V at WOT.

[Ryland3210]

I found the TPS calibration off by 45 mv. Starting from Jeff from Ohio's procedure, I developed a procedure summary. My goal was to eliminate iterative interdependent adjustments and the effects of any backlash in the connecting rod.

 

My Draft Procedure Summary: First make sure the TPS is calibrated to 150 mv at fully closed as follows: disconnect the connecting rod, back off the right throttle idle screw and choke cam (make sure the choke cable permits full retraction of the cam (it didn't on my bike), then loosen the TPS clamp screws and rotate if needed. + - 5 mv can be obtained with a little effort.

 

Next, close the bypasses, keep the right throttle idle screw backed off to put the connecting rod in tension, removing any backlash, and balance the throttles at idle using the connecting rod adjustment. Screw in the left throttle idle screw if the idle is too low to maintain. Do not use the choke for this purpose, because that would put the connecting rod in compression, introducing backlash.

 

Now adjust the left idle screw for a TPS reading of .518 volts. + - .005 (corresponding to 3.4 degrees physical opening) can be obtained with a little effort. (Some riders have been known to also subsequently physically readjust the TPS (not the idle screw) to lean or richen the entire throttle range. However, loosening its screws and offsetting the TPS to a higher voltage, e.g. .539, will fool the ECU into adding more fuel, but it will also fool the ignition timing table.)

 

Next open the bypasses to obtain the idle RPM at 1100 to 1200 while maintaining balance. Bypasses should be open 1/2 turn or more. If not, back off the idle screw to reduce the TPS in steps of 15 mv and open the bypasses to compensate until they are opened 1/2 turn or more. Check balance at midrange RPM as follows:

 

A When checking balance at cruise RPM, make any fine correction needed using the connecting rod adjustment, then:

B. Check balance at idle RPM. If OK, done, if not, rebalance at idle using the air bypass screws, and go back to step A.

 

Option: Adjust the idle mixture trim potentiometer under the label of the computer for best idle quality, or use a gas analyzer if available. However, according to Guzzijack, "not an option on the V11Sport as it uses the 15M ECU - manual adjustment of the idle mixture potentiometer is only applicable to bikes with the P7/P8 or 16M ECUs - 15M idle mixture adjust is only possible via factory or aftermarket software."

 

Once this procedure is completely successfully, in the future, minor changes in idle speed can be made simply by adjusting the left throttle idle screw. Since the throttle plates have been balanced, backlash between them has been eliminated, and bypasses have been properly adjusted to maintain balance at idle, these should be stable for many miles.

 

Comments, anyone?

[dlaing]

I found the TPS calibration off by 45 mv. Starting from Jeff from Ohio's procedure, I developed a procedure summary. My goal was to eliminate iterative interdependent adjustments and the effects of any backlash in the connecting rod.

 

My Draft Procedure Summary: First make sure the TPS is calibrated to 150 mv at fully closed as follows: disconnect the connecting rod, back off the right throttle idle screw and choke cam (make sure the choke cable permits full retraction of the cam (it didn't on my bike), then loosen the TPS clamp screws and rotate if needed.

 

Next, close the bypasses, keep the right throttle idle screw backed off to put the connecting rod in tension, removing any backlash, and balance the throttles at idle using the connecting rod adjustment. Screw in the left throttle idle screw if the idle is too low to maintain. Do not use the choke for this purpose.

 

Now adjust the left idle screw for a TPS reading of .485 volts.

 

Next open the bypasses to obtain the idle RPM at 1100 while maintaining balance. Check balance at midrange RPM.

 

Option: Adjust the idle mixture trim potentiometer under the label of the computer for best idle quality, or use a gas analyzer if available.

 

Comments, anyone?

I like the clarity regarding how the air bypass screws might be used.

I am still not sure about the .485 V setting. I think it is better to suggest a range there, and also include whether or not the bike is running and if so, whether or not you expect it to hold an idle at 485mV± ??mV

I tend to favor an RPM of 1100-1200, but 1100 may be fine and even 1000RPM may have advantages like smoother shifting from neutral to first and the bike may run cooler in stop and go, 5 minute red lights in the middle of Summer in congested traffic.

Are you sure there is a potentiometer under the label???

And a blurb about CO is always helpful...

[guzzijack]

 

Option: Adjust the idle mixture trim potentiometer under the label of the computer for best idle quality, or use a gas analyzer if available.

 

Comments, anyone?

 

 

Not an option on the V11Sport as it uses the 15M ECU - manual adjustment of the idle mixture potentiometer is only applicable to bikes with the P7/P8 or 16M ECUs - 15M idle mixture adjust is only possible via factory or aftermarket software.

 

GJ

[Ryland3210]

I like the clarity regarding how the air bypass screws might be used.

I am still not sure about the .485 V setting. I think it is better to suggest a range there, and also include whether or not the bike is running and if so, whether or not you expect it to hold an idle at 485mV± ??mV

I tend to favor an RPM of 1100-1200, but 1100 may be fine and even 1000RPM may have advantages like smoother shifting from neutral to first and the bike may run cooler in stop and go, 5 minute red lights in the middle of Summer in congested traffic.

Are you sure there is a potentiometer under the label???

And a blurb about CO is always helpful...

 

See my edits in the draft procedure, taking your comments into account. There have been many varying opinions on what voltage to adjust to. I think the target of .485 allows newcomers to have a specific target so they do not have to wonder where to adjust to within a range. I added the comment about readjusting the TPS for those more advanced tuners.

On my bike, there was no big difference on voltage readings whether the engine was on or off. Since the reference voltage is regulated, it theoretically should make no difference. However, if the battery is weak enough to drop its voltage below its regulating range when the engine is off, that could be a factor. This could be overcome by connecting a charger to the bike so the voltage is always at the running voltage. I found I did not have to do this. Also, if there is a poor ground at the ECU or in the charging circuit, that could cause a problem.

On the CO, I think the "gas analyzer" comment is general enough.

 

 

Not an option on the V11Sport as it uses the 15M ECU - manual adjustment of the idle mixture potentiometer is only applicable to bikes with the P7/P8 or 16M ECUs - 15M idle mixture adjust is only possible via factory or aftermarket software.

 

GJ

 

Thanks for the comment. I have incorporated it into the draft above.

[docc]

I think 485mV is too low. There are no advantages to idling too low. Can anyone with the Axone or software confirm the disparity in readings from the crank sensor to the indication on the tach?

 

Jeff says 500-525 in his procedure. I found a conversion (thought it was on GuzziTech) for the 3.2-3.6 degrees opening which indicates a range of 466-521 mV. (494 appears to be midrange).

 

I've tried lower settings to save fuel. Consumption didn't change and the bike ran worse.