Throttle Position Sensor

[BrianG]

I think the idle speed TPS value is as useful as an idle RPM spec. It's an interesting indication of what the factory thinks is appropriate, but it's really a matter of taste.

 

The closed throttle value is a datum point, or baseline spec. From that point on the ECU responds with the appropriate amount of fuel for the throttle opening, no matter what the opening amount is.

 

So who cares that you may like a Harley Davidson idle of 800 RPM and I like a race-track idle of 1400 RPM? As long as the baseline TPS value was correct, the idle TPS value will be appropriate for the chosen RPM...

 

Since the A/F map is simply a software algorithm that takes its primary fuel requirement indication from the TPS voltage, one could mess with altering the closed throttle/baseline datum point voltage in the same way as you would mess with main jets in order to find best milage or best power or whatever other parameter diddling with A/F ratios might net you.

 

Of course this will just get you into trouble as it has gotten me... having a wide-band A/F gage and my PC lll, I targeted Stoich (14.7:1 A/F) for less-than-1/3 throttle..... fading toward Best Power (12.6:1 A/F) at greater than 2/3 throttle. It doesn't feel much different than the map that the DynoTech dyno wrote, so we'll see what the milage does.....

 

All I can say is that it's easier than swapping jets!

 

And as to this idle-mixture screw for the final TB balancing............. that's just WRONG! Given that correct idle mixture is a separate entity, adjusted with this jet..... varying from the "right" mixture to affect idle speed (rather than varying throttle opening) is akin to altering idle speed by jamming your boot against the flywheel to adjust idle speed. I mean really... just because a side effect of "wrong" idle mixture is depressed idle speed, how do we get to where we think it's the right thing to do??

[dlaing]

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.

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

I would have to verify the following with a repeated test, but I found no difference in TPS voltage with charger on or off, and I found that at running idle it was around 10-20mV higher, and seemed inconsistent. Also, I found that trying to keep the idle steady, running mostly off of the left cylinder, was a pain. I think the only recommendation for testing the 150mV reading while running comes from Will Creedon/Carl Allison and was likely the first available technique to be mentioned on this forum and was likely based on experience with V1100 five speeds, where it was likely more critical.

[luhbo]

.....

And as to this idle-mixture screw for the final TB balancing............. that's just WRONG! Given that correct idle mixture is a separate entity, adjusted with this jet..... varying from the "right" mixture to affect idle speed (rather than varying throttle opening) is akin to altering idle speed by jamming your boot against the flywheel to adjust idle speed. I mean really... just because a side effect of "wrong" idle mixture is depressed idle speed, how do we get to where we think it's the right thing to do??

 

I think, nobody was talking of using an idle-mixture screw for final TB balancing. Look and you won't find such a screw on these bikes. Opening the bypass screws just gives a little bit more air flow, it's more or less exactly the same as slightly opening the flaps.

 

The main difference here to carbs is the fact, that opening a slider gives a linear increase of flow or duct area. Turning the throttle flap gives a very non linear increase of the flow area. One or two degrees opening are a lot more difference as from 75 to 90.

 

That's also the reason for the very fine solution of map index steps from 1 to 30 degrees compared to that between 30 and 90. In other words, 66% of the TPS signal are used for the first 30 degrees of opening. You need these bypass screws to eliminate tolerances, because these tolerances have such a big effect.

 

 

Hubert

[Ryland3210]

I would have to verify the following with a repeated test, but I found no difference in TPS voltage with charger on or off, and I found that at running idle it was around 10-20mV higher, and seemed inconsistent. Also, I found that trying to keep the idle steady, running mostly off of the left cylinder, was a pain. I think the only recommendation for testing the 150mV reading while running comes from Will Creedon/Carl Allison and was likely the first available technique to be mentioned on this forum and was likely based on experience with V1100 five speeds, where it was likely more critical.

 

The 10-20 mv higher and inconsistency while running now sounds like electrical noise, vibration of the TPS shaft or both. Doing the 150mv reading while running with right throttle completely closed must be a pain. I see no advantage to having the engine running for this test, except to eliminate a 10-20mv difference, which is a small percentage of a 4.850 range. I only see a 1-2 mv variation in the 485mv TPS voltage while running at 1100 RPM, so maybe my bike has some good grounding and/or less electrical noise radiation.

[dlaing]

I think, nobody was talking of using an idle-mixture screw for final TB balancing.

I believe the idle mixture (air bypass) screws should be used for final TB balancing at idle.

I suppose we could scrap the whole at idle TPS measuring scheme.

The correct RPM should be good enough, and TPS should be set to the absolute limit of the throttle body butterfly valves. Either fully open or fully closed.

Throttle bodies should be balanced first at 2000-3000 RPM, IMHO idle should be set initially with bypass screws at a half turn out and then if the idle balance is off, tweak the difference with the air bypass screws. I think it is better to only use the left set screw and balance the idle with the air bypass screws, although I have used the right set screw to balance the idle, but I now think it is a mistake.

At idle the ECU controls how much fuel goes to each cylinder. For tuning purposes there is no enrichment screw. We only have control of what balance of air is entering through balancing butterfly valves and bypass screws. Using a vacuum meter we can reasonably assume that if we are balanced, the mixture is also balanced.

Ideally the throttle bodies balance evenly from idle to 3000 RPM and the air screws are each opened 1/2 turn, but realistically the balance is not always even and the bypass screws can and should be used, IMHO, until proven otherwise.

However, if you can balance the TBs and keep the air bypass screws out to the same setting, fantastic!

Should the amount of air bypass be determined by the difference between a set TPS reading of 485mV and a desired idle?

I suspect this is what Brian is most concerned about.

I am not positive, but if TPS is set to 150mV and butterfly valves are opened till it reaches 485mV (or whatever) and the bike is holding an idle, then opening the air bypass screws up to get 1100 RPM will PROBABLY have an excellent result, but it also may lead to overly lean conditions or even overly rich conditions

 

 

The 10-20 mv higher and inconsistency while running now sounds like electrical noise, vibration of the TPS shaft or both. Doing the 150mv reading while running with right throttle completely closed must be a pain. I see no advantage to having the engine running for this test, except to eliminate a 10-20mv difference, which is a small percentage of a 4.850 range. I only see a 1-2 mv variation in the 485mv TPS voltage while running at 1100 RPM, so maybe my bike has some good grounding and/or less electrical noise radiation.

Interesting

I figured it had something to with how the ECU, Coils, and/or engine positions sensor?????????

[Ryland3210]

I believe the idle mixture (air bypass) screws should be used for final TB balancing at idle.

I suppose we could scrap the whole at idle TPS measuring scheme.

The correct RPM should be good enough, and TPS should be set to the absolute limit of the throttle body butterfly valves. Either fully open or fully closed.

Throttle bodies should be balanced first at 2000-3000 RPM, IMHO idle should be set initially with bypass screws at a half turn out and then if the idle balance is off, tweak the difference with the air bypass screws. I think it is better to only use the left set screw and balance the idle with the air bypass screws, although I have used the right set screw to balance the idle, but I now think it is a mistake.

At idle the ECU controls how much fuel goes to each cylinder. For tuning purposes there is no enrichment screw. We only have control of what balance of air is entering through balancing butterfly valves and bypass screws. Using a vacuum meter we can reasonably assume that if we are balanced, the mixture is also balanced.

Ideally the throttle bodies balance evenly from idle to 3000 RPM and the air screws are each opened 1/2 turn, but realistically the balance is not always even and the bypass screws can and should be used, IMHO, until proven otherwise.

However, if you can balance the TBs and keep the air bypass screws out to the same setting, fantastic!

Should the amount of air bypass be determined by the difference between a set TPS reading of 485mV and a desired idle?

I suspect this is what Brian is most concerned about.

I am not positive, but if TPS is set to 150mV and butterfly valves are opened till it reaches 485mV (or whatever) and the bike is holding an idle, then opening the air bypass screws up to get 1100 RPM will PROBABLY have an excellent result, but it also may lead to overly lean conditions or even overly rich conditions

Interesting

I figured it had something to with how the ECU, Coils, and/or engine positions sensor?????????

 

My understanding is that the ECU determines how much fuel to inject based on inputs of engine temperature, TPS, and RPM. Let's assume the engine is warmed up to normal operating temperature.

Let's consider what happens when opening the bypass settings from full closed while the TPS stays at .485 volts.

As the bypass air is increased, if the RPM increases, it means the engine wants a leaner mixture, but at the same time, as RPM increases injected fuel will increase. On my bike, the vacuum increased along with RPM, so I believe the mixture was improving, towards the lean side.

At a constant TPS voltage and throttle position, the more the bypasses are opened, the leaner the mixture. Reading between the lines of the recommended 1/2 turn for the bypasses, and an 1100 RPM idle speed, I suppose the Guzzi techs have the ECU programmed to deliver a slightly rich mixture when the bypasses are set there.

If one ends up with bypasses more open than that, keeping the TPS calibration the same, the idle mixture will be leaner, but as the throttle is opened more and vacuum decreases, the contribution of the bypasses will diminish, so at higher RPM or higher loads, mixture will revert to the factory's intended mixture. In my case, when the bypasses ended up at just over 1 turn out each, I was happy to have a little leaner idle mixture, knowing that with the TPS calibrated and throttle plates balanced, I could expect better fuel economy without sacrificing acceleration.

 

Personally, I think it is preferable to balance the throttles at low openings because at, for example, 25% open or more, a degree off balance for the throttle plates is much less significant than at or near idle. In fact, when I balanced the system in accordance with my draft procedure, I found the vacuums balanced out perfectly at 2500 -3000 RPM

[dlaing]

My understanding is that the ECU determines how much fuel to inject based on inputs of engine temperature, TPS, and RPM.

Yes, and air pressure and air temperature.

Let's assume the engine is warmed up to normal operating temperature.

Let's consider what happens when opening the bypass settings from full closed while the TPS stays at .485 volts.

As the bypass air is increased, if the RPM increases, it means the engine wants a leaner mixture, but at the same time, as RPM increases injected fuel will increase.

You would think so, but take a look at what happens at idle, presumably at 3.? degrees which correlates to somewhere between 1.99 and 4.18. Notice what happens, or rather what does not happen, as RPMs go from 900 to 1300.

EDIT also note, that increasing the TPS won't do much for idle richness.

At a constant TPS voltage and throttle position, the more the bypasses are opened, the leaner the mixture. Reading between the lines of the recommended 1/2 turn for the bypasses, and an 1100 RPM idle speed, I suppose the Guzzi techs have the ECU programmed to deliver a slightly rich mixture when the bypasses are set there.

US idle CO trim is pretty lean. 1.9%

World idle CO trim a lot richer. 3-5% http://www.mphcycles.com/Technical/Technical2.htm

Ideally we all have Axeone or Motorbike Diagnostic Software to reset the trim and a CO meter <_>

If one ends up with bypasses more open than that, keeping the TPS calibration the same, the idle mixture will be leaner, but as the throttle is opened more and vacuum decreases, the contribution of the bypasses will diminish, so at higher RPM or higher loads, mixture will revert to the factory's intended mixture. In my case, when the bypasses ended up at just over 1 turn out each, I was happy to have a little leaner idle mixture, knowing that with the TPS calibrated and throttle plates balanced, I could expect better fuel economy without sacrificing acceleration.

 

Personally, I think it is preferable to balance the throttles at low openings because at, for example, 25% open or more, a degree off balance for the throttle plates is much less significant than at or near idle. In fact, when I balanced the system in accordance with my draft procedure, I found the vacuums balanced out perfectly at 2500 -3000 RPM

That makes sense. But still you don't want your idle to be too lean.

[BrianG]

I think, nobody was talking of using an idle-mixture screw for final TB balancing. Look and you won't find such a screw on these bikes. Opening the bypass screws just gives a little bit more air flow, it's more or less exactly the same as slightly opening the flaps.

 

The main difference here to carbs is the fact, that opening a slider gives a linear increase of flow or duct area. Turning the throttle flap gives a very non linear increase of the flow area. One or two degrees opening are a lot more difference as from 75 to 90.

 

That's also the reason for the very fine solution of map index steps from 1 to 30 degrees compared to that between 30 and 90. In other words, 66% of the TPS signal are used for the first 30 degrees of opening. You need these bypass screws to eliminate tolerances, because these tolerances have such a big effect.

 

 

Hubert

 

If the screw bleeds air without affecting fuel, it is an idle mixture adjustment. If it were a vernier throttle-plate stop adjustment, shifting the TPS (fuel) as well as the throttle plate (air), I'd agree.

 

The significant issue with regard to that bleed screw position is that there is no easy reference for "correct". As mentioned above, few have access to a CO meter, and even my WB-O2 meter gives weak references at idle.

 

There is little point to getting too excited about this setting's measurement since it will have to be "close enough" to give decent idle character, it is a useful TB balance trimmer, and it has little effect on that portion of the throttle opening where significant power is being made, where mixture become critical.

[guzzijack]

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.

 

Where did this 'target' of 485mV come from? Is it just a repetition of the erroneous quote of WOT being ".485V"? If you look at the MPH website for a conversion of the software target of 3.6 degrees of butterfly opening at 1060+/-50 rpm it actually equates to 524mV.

 

GJ

[dlaing]

Where did this 'target' of 485mV come from? Is it just a repetition of the erroneous quote of WOT being ".485V"? If you look at the MPH website for a conversion of the software target of 3.6 degrees of butterfly opening at 1060+/-50 rpm it actually equates to 524mV.

 

GJ

The MPH chart is for a California Stone.

My quoted error of .485V (should have been 4.85V) is coincidental and may have been subconsciously driven by the considered idle target of 485mV.

Todd Eagan at Guzzitech has been setting the TPS up to higher than 500mV prior to tuninglink dyno sessions for a long time, probably basing it on the MPH Cali Stone numbers. I think most people on the list, myself included, were doing the same.

Docc also noted that his bike runs better at a setting much higher than 485mV

But as we may have only recently learned from Mr. Bean, Moto International and others, the numbers may in fact be lower than the Cali Stone chart indicates.

[guzzijack]

The MPH chart is for a California Stone.

My quoted error of .485V (should have been 4.85V) is coincidental and may have been subconsciously driven by the considered idle target of 485mV.

Todd Eagan at Guzzitech has been setting the TPS up to higher than 500mV prior to tuninglink dyno sessions for a long time, probably basing it on the MPH Cali Stone numbers. I think most people on the list, myself included, were doing the same.

Docc also noted that his bike runs better at a setting much higher than 485mV

But as we may have only recently learned from Mr. Bean, Moto International and others, the numbers may in fact be lower than the Cali Stone chart indicates.

 

Not that page - although it is relevant - look at the figures on This page. All of the 15M ECU bikes, (apart from the Quota of course), including the V11Sport, Bassa and California Jackal should have the same setting of 3.6 degrees of throttle opening @ 1060 +/- 50 rpm when viewed via the factory or other software. This is the factory standard setting which of course can be played around with but nevertheless it is the 'target' if you wish to have some kind of datum point to refer to.

 

I see you're at it again in your message quoted above. Where does your, "considered idle target of 485mV", come from? Is it factory published data?

 

Do you seriously think that the 2002 California Stone with it's identical 15M ECU, PF3C TPS and a 'baseline' setting of 150mV, (yes, that's the same configuration as the three models mentioned above!), has some other weirdo method of measuring the TPS output at a given throttle opening?

 

If the butterfly 'totally closed' setting is 150mV then 3.6 degrees of opening will give you 524mV from a PF3C TPS no matter which model of bike you have, (with maybe small allowances for manufacturing tolerances of course), even my '97 Cali EV will give the same figure although the P8 ECU and different TBs require a smaller butterfly opening to achieve the 'factory standard' setting. Small wonder that Todd Egan, Docc et al have better running bikes with a TPS reading at idle of "higher than 500mV" as that's where it's supposed to be!

 

GJ

[Ryland3210]

Not that page - although it is relevant - look at the figures on This page. All of the 15M ECU bikes, (apart from the Quota of course), including the V11Sport, Bassa and California Jackal should have the same setting of 3.6 degrees of throttle opening @ 1060 +/- 50 rpm when viewed via the factory or other software. This is the factory standard setting which of course can be played around with but nevertheless it is the 'target' if you wish to have some kind of datum point to refer to.

 

I see you're at it again in your message quoted above. Where does your, "considered idle target of 485mV", come from? Is it factory published data?

 

Do you seriously think that the 2002 California Stone with it's identical 15M ECU, PF3C TPS and a 'baseline' setting of 150mV, (yes, that's the same configuration as the three models mentioned above!), has some other weirdo method of measuring the TPS output at a given throttle opening?

 

If the butterfly 'totally closed' setting is 150mV then 3.6 degrees of opening will give you 524mV from a PF3C TPS no matter which model of bike you have, (with maybe small allowances for manufacturing tolerances of course), even my '97 Cali EV will give the same figure although the P8 ECU and different TBs require a smaller butterfly opening to achieve the 'factory standard' setting. Small wonder that Todd Egan, Docc et al have better running bikes with a TPS reading at idle of "higher than 500mV" as that's where it's supposed to be!

 

GJ

 

Using your numbers, 524 mv minus 150 mv divided by 3.6 degrees equals 104 mv/degree.

Therefore a TPS of 485 mv corresponds to 3.22 degrees. It simply means that if the bypasses are successfully opened up enough to obtain the same target RPM as with a TPS of 500mv or 524 mv, it seems to me the only difference is that the setup at 485 mv is leaner than at higher TPS settings.

 

As throttle opening is increased, the bypass airflow is less significant. At some poiint, it becomes insignificant, so fuel/air ratio is the same regardless of the idle setup.

 

Bottom line to me is:

1. For any idle setup, whether at 485 or 524 which has the TPS set to 150mv at full closed, cruise and acceleration mixture is essentially unaffected. Only the idle mixture ratio is affected.

 

2. Those who wish to modify the mixture over the entire range can do so by deliberately offsetting the TPS from standard calibration.

 

3. Balancing the throttle plates and bypasses in accordance with the most recent revision of the draft procedure is still valid.

 

[dlaing]

Not that page - although it is relevant - look at the figures on This page. All of the 15M ECU bikes, (apart from the Quota of course), including the V11Sport, Bassa and California Jackal should have the same setting of 3.6 degrees of throttle opening @ 1060 +/- 50 rpm when viewed via the factory or other software. This is the factory standard setting which of course can be played around with but nevertheless it is the 'target' if you wish to have some kind of datum point to refer to.

 

I see you're at it again in your message quoted above. Where does your, "considered idle target of 485mV", come from? Is it factory published data?

 

Do you seriously think that the 2002 California Stone with it's identical 15M ECU, PF3C TPS and a 'baseline' setting of 150mV, (yes, that's the same configuration as the three models mentioned above!), has some other weirdo method of measuring the TPS output at a given throttle opening?

 

If the butterfly 'totally closed' setting is 150mV then 3.6 degrees of opening will give you 524mV from a PF3C TPS no matter which model of bike you have, (with maybe small allowances for manufacturing tolerances of course), even my '97 Cali EV will give the same figure although the P8 ECU and different TBs require a smaller butterfly opening to achieve the 'factory standard' setting. Small wonder that Todd Egan, Docc et al have better running bikes with a TPS reading at idle of "higher than 500mV" as that's where it's supposed to be!

 

GJ

That MPH page only show the 3.6° spec for the V11, not the corresponding mV TPS reading.

Here is the source thread that contains Mr. Beans correlation of 3.6° to 485mV

http://www.v11lemans.com/forums/index.php?showtopic=11946

I have not verified Mr. Bean's claim.

Since you seem "at it again", asking so politely, I'll go out to the garage now and verify.

[dlaing]

I am happy to find my TPS hanging in nicely where set at 527mV which does in fact correspond to 3.6°.

At WOT it is 4.87V which corresponds to 85.5°

So, I suspect Mr. Bean or his meter was mistaken.

I think Ryland should redo his instructions to recommend 525mV.

NOTE I used TuneBoy and not TechnoResearch nor AxeONE

This does not mean that 485mV is wrong.

And it not being wrong does not mean my 527 is wrong.

The more critical number is still the 150±15mV

Although from now on I may just set it to 4.87V at WOT...although I just measured that with linkage connected, so it may be WRONG

I'll have to measure the WOT TPS V more carefully.

 

The manual suggests that at idle the throttle should be open 3.6°±0.5 which is 3.1 to 4.1° which according to MPH's chart corresponds to, whatever...you go do the math, but the point is that at 3.1° the mV will be will below 485mV and still tuned to spec...but not necessarily tuned well.

Here is an excerpt from the the MPH chart

DEGREES	VOLTS	  2002 California Stone
3.4	0.501 	
3.6	0.524 	
3.9	0.567 	
4.1	0.579 	
4.8	0.657 

84.4	4.86V

[guzzijack]

I am happy to find my TPS hanging in nicely where set at 527mV which does in fact correspond to 3.6°.

At WOT it is 4.87V which corresponds to 85.5°

So, I suspect Mr. Bean or his meter was mistaken.

I think Ryland should redo his instructions to recommend 525mV.

 

 

So, are we finally in agreement then?

 

If there is a need for a reference point to start setting up a 15M ecu equipped bike, including the V11Sport, and you don't have access to whatever brand of software, then 525mV @ 1060 +/- 50 rpm idle is a good point to aim for. Higher or lower readings may be be reached as a final tweaking but if you start at 485mV and then apply your +/- .5 degree (approx 100mV) then it could drop way too low. Maybe Mr Bean has read the 485mV TPS @ 3.6 degrees but from a zero start setting and without the 150mV pre-dialled in?

 

GJ