TPS break points at low throttle openings

[docc]

14 minutes ago, Lucky Phil said:

https://www.bikeboy.org/ducatitps.html

 

Phil

Thanks for the Required Reading!

Yet, this appears most applicable to the linear 18mV step TPS with preset throttle pates, not our "two-stage-linear" adjustable PF4C  . . .

[docc]

I'm gonna try to interpolate the break points of our TPS from this graph . . .

[Lucky Phil]

25 minutes ago, docc said:

Thanks for the Required Reading!

Yet, this appears most applicable to the linear 18mV step TPS with preset throttle pates, not our "two-stage-linear" adjustable PF4C  . . .

I posted for the first linier v non linier graph docc. More general weber info. The V11 sport uses either the PF03 non linier or PF03c (without adjustment slots) linier does it not. From memory. My bike uses the PF09 non linier, a larger version of the PF03.

https://www.bikeboy.org/ducati2vthrottleb.html

 

Phil

 

[Lucky Phil]

21 minutes ago, docc said:

I'm gonna try to interpolate the break points of our TPS from this graph . . .

It's been done, I've read it somewhere years ago.

 

Phil

[docc]

2 minutes ago, Lucky Phil said:

It's been done, I've read it somewhere years ago.

 

Phil

Me, too. Having trouble re-finding it . . .

And, to clarify, trying to discern the "steps"/break points in the original 15M V11 ECU map in millivolts sent from the TPS in the lower throttle angles . . .

[Lucky Phil]

4 hours ago, docc said:

Me, too. Having trouble re-finding it . . .

And, to clarify, trying to discern the "steps"/break points in the original 15M V11 ECU map in millivolts sent from the TPS in the lower throttle angles . . .

Here you go Docc. TPS lookup table in Volts. I'm thinking that what you should see with a correctly set TPS at 157MV at fully shut throttle is column 8. As a computer luddite thats what I figure. The throttle angle values are the vertical scale in hex and all the other vertical scales are for an incorrect base setting and the ecu interpolates between what it should be and what it sees. Not sure in reality. Above my "G" I'm afraid.

Phil

[docc]

Thanks, Lucky_Phil.  I haven't been able to get my brain around the quantitative difference in the the "closer" breakpoints in the steeper part of the TPS output.

Using @Meinolf's breakpoint derivation, I can only get as far as less than about +/- 9.8 mV. But just how much narrower is the range in the lowest throttle openings . . .

[Lucky Phil]

6 hours ago, docc said:

Thanks, Lucky_Phil.  I haven't been able to get my brain around the quantitative difference in the the "closer" breakpoints in the steeper part of the TPS output.

Using @Meinolf's breakpoint derivation, I can only get as far as less than about +/- 9.8 mV. But just how much narrower is the range in the lowest throttle openings . . .

Here's another image docc, not sure if it helps. TPS in break/sampling points in degrees. On the vertical column there are break points or ecu sampling point's I guess every 2.9-3 degrees up to 29.4 degrees of throttle angle and from there to 84.1 it's now every 10-12 degrees or so. So the ecu sampling points are stacked tighter up to that 29.4 degrees so the resolution is greater I guess.    

Other than that I got nothing. I'll think about it some more and try and figure it out. It may take some time, lol. Whatever it is you can still get a nice running engine without knowing the high resolution detail with some fiddling and basic tuning knowledge. 

Phil

[audiomick]

2 hours ago, Lucky Phil said:

So the ecu sampling points are stacked tighter up to that 29.4 degrees so the resolution is greater I guess. 

Yes.

It's the same principle, but reversed, as the logarithmic faders on an audio console. They do big steps at the bottom of the range of movement, and small steps towards the top of the range around the nominal level point, marked 0 dB. Typically, the first centimetre or so (depending on how physically long the fader is...) above and below 0 dB makes changes in the range up to +/- 10 db. Down at the bottom end, the same physical displacement of around a centimetre is more like 40 dB. The reason is, if you have your signal structure set up "right", your faders are all going to be somewhere near the nominal level, i.e. physically near the 0 dB mark. Subtle changes in the mix require a definite move of the fader to make a fairly small difference. The same definite move down towards the bottom of the range (where the fader theoretically only passes through during a complete fade-out) results in a level change that is anything other than subtle.

Getting back to the motorbike: riding on the street, we spend most of our time below half-throttle or so. The non-linear TPS means that in that range, a specific movement of the throttle will trigger more break points than the same physical movement above the point where the characteristic changes, i.e. above the 30-odd degrees that Phil referred to.

That makes sense: letting out the clutch, riding in traffic, accelerating out of the corner (road or race-track) all require fine control of the throttle, and all happen at (roughly speaking) less than half throttle opening. Above half open, it is generally about maximum acceleration, and tends to be a bit "digital", i.e. full throttle or closed throttle.

Therefore, it is theoretically an advantage to have the ECU receive more break points in the lower range of throttle opening at the cost of larger jumps in the upper range of throttle opening.

On top of that, there is also the thing that the relative change of the size of the air passage past the throttle valve is greater in the lower range of opening than it is in the upper range. That means, once again very roughly speaking, a change from "nearly shut" to "open a bit" might be equivalent to, for instance, "a bit over three quarters" to "flat out". Therefore, the  three degrees difference between 5.9 and 8.8 may effectively not be so drastically less than the 12 or so between 50.4 and 60.1 as it seems at first glance.

Having written all of that, the manufacturer apparently decided it all wasn't worth the effort. I gather newer TPSs than the ones in our V11s tend to be linear.

[Weegie]

Can I ask which ECU we're discussing here?

I'm going to reset the TPS and then do a throttle body balance on the Australia later this year, Hi Cam engine like the Daytona & 16M ECU.

Anybody care to comment if there would be any benefit in setting my TPS to 157mV per Meinolf recommendations?

[Lucky Phil]

2 hours ago, Weegie said:

Can I ask which ECU we're discussing here?

I'm going to reset the TPS and then do a throttle body balance on the Australia later this year, Hi Cam engine like the Daytona & 16M ECU.

Anybody care to comment if there would be any benefit in setting my TPS to 157mV per Meinolf recommendations?

15M. This isn't some magical Meinolf figure John it's the factory setting for the V11 Sport. Your bike is 150MV +- 15mv so 157 is well withing the tolerance.

 

Phil

[audiomick]

3 hours ago, Lucky Phil said:

...This isn't some magical Meinolf figure ...

Not magical, but I gather Meinolf took the time to sit down and do the maths to find out the optimum number based on the numbers in the map. As Phil said, the result is, not surprisingly, well within the tolerance stated in the workshop book. At least in the one for the V11.

[Meinolf]

8 hours ago, audiomick said:

...Meinolf took the time to sit down and do the maths....

Hi,

it didn't take that much time. The 157mV instead of 150mV is simply based on a rounding error in the OEM TPS lookup table.

5V/255=0,01953V
8x0,01953= 0,1563V=156,3mV

Now one may argue if the 6,3mV difference is significant. No, it isn't. But why use a wrong value if the correct one is known.

Cheers
Meinolf

 

[Meinolf]

Hi,

as to the question why more TPS breakpoints are used in the low range than in the upper. It's about flow area increase when the butterfly valve is opened. The flow area resulting from the movement is based on a rather complicated cosine formula, several years ago Beard kindly wrote a small program to simplify the calculation.

Looking at the 1st (TPS degree) and 4th column (free flow area in mm^2 including the butterfly axle diameter) one can derive the change in %.

7.7/5.2=1.46=46% increase
22.0/20.0=1,1=10% increase

So, ~2.3 TPS degree change at low throttle opening result in 46% flow area increase, a 2.0 TPS degree change in mid range is 10% flow area.

It makes sense to use TPS breakpoints which provide the a like flow area increase.

Cheers
Meinolf

[docc]

From that, @Meinolf, can the tolerance of the TPS setting at those low throttle angles be derived.

+/- 15 mv, or a range of 30 mV, seems excessive. It must be tighter than +/- 9.8 mV at the low throttle angles (and for the baseline setting) . . .