moto
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Posts posted by moto
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Could the O2 readings be wrong because you are not holding it the setting for a full 40 seconds?
http://www.andros.com/6800spec.htm
Or am I reading the specs wrong, and that
Also the O2 sensor is accurate + or - 0.1 % which is fine, but we should not be nitpicking between a 0.1 and a 0.3%...but then again, I'll bet that on a given day the accuracy is much greater.
the plus or minus point one probably is against a standard rather than the same machine against itself.
How quickly an EGA can respond depends to a large degree upon the speed whith which one can deliver the sample to the sensor. Andros uses fairly low volume pumps because water vapor has a greater chance to condense and filters stay cleaner longer (there may be reasons having to do with the other fields their analyzers are used in). This is fine for emissions testing, but not for performance tuning. I use a very high volume pump (comparatively), which speeds the sample delivery rate considerably, use a sample cooler to get the moisture to condense before it gets to the bench, and change the filters often. It's also important to note that the
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From moto's post it is clear that he is tuning for best power. Great, looks very nice on a inertial dyno. But the rich mixture does not always work best for more sedate driving.
Best power is not always the best target.
Using closed loop is not a perfect solution, but it is better at achiving good combustion efficiency over the long term under a wider range of running conditions. Will this always make the most power, NO, but neither will tuning for a target CO on a dyno, which is a very poor simulation for actual running conditions. Driving around with your 5 gas straped to your seat could be a very expensive experiement. (Even though I have done it.)
I am absolutely tuning for best power, but I don't use an inertial dyno. I'm not sure what made you think I do, since no one (at least that I am aware of) manufactures an inertial dyno with an integrated EGA, as it's very difficult if not impossible to sort out the delays properly. What makes you think the mixture is rich in the data I provided? What criterion is used to make this judgement? As far as I'm concerned, if I'm making best bower at a particular throttle position and rpm combination, the mixture is not rich. Once again, I have to ask the question, why do we tune in the first place if it is not to make power?
As originally stated, the data in the last chart I posted is at 100% throttle. Why are we talking about sedate driving at 100% throttle? None of that data has anything to do with those throttle positions which one might consider "sedate". But even at those throttle positions I tune to best power when possible, and I see no logical reason why I should not. Here's the Futura's final rear cylinder data at 12% throttle (which I'm sure we can agree is "sedate"), pulsewidths again tuned to within ±.1 to ±.2 hp of best power:
Rpm HP ft/lbs CO O2
1455 7.30 26.41 3.4 0.4
1902 9.80 27.11 4.1 0.5
2355 10.61 23.61 3.9 0.5
2653 13.21 26.11 4.4 0.6
3005 14.81 25.91 4.0 0.4
3304 15.71 25.01 4.2 0.7
3604 16.51 24.11 3.8 0.9
4005 17.51 23.01 3.5 1.6
4405 17.71 21.11 3.1 0.7
4906 19.91 21.31 2.7 1.8
5405 20.01 19.41 2.8 0.5
6002 18.31 16.11 4.0 0.5
6401 20.11 16.51 3.9 0.4
6805 20.21 15.61 3.9 0.8
7104 18.91 14.01 3.8 0.5
7402 18.01 12.81 2.7 0.5
7810 17.71 11.91 2.3 0.4
8310 15.29 9.60 4.4 0.7
8805 11.47 6.86 2.8 0.7
If best power is not the best target, then what is and why?
What is the argument that closed loop is always better at achieving good combustion efficency based on?
True that tuning fuel to CO targets on a dyno will not always produce the best power, but it will produce better power than using O2 (or "A/F ratio") targets, especially before timing and/or stagger issues have been adressed. But why use gas content targets as anything other than a rough guide when one can tune to best power?
An EGA will only produce meaningful data during steady state conditions, so you would have had to produce steady state conditions in your car. What is the difference between producing steady state conditions in your car and producing them on a dyno? If anything, many steady state conditions that are no problem to produce on a brake dyno are very difficult to produce while driving around.
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I put Moto's data into more of a chart form
HP RPM CO O2
62.7 6000 11.4 0.4
67.6 6000 4.7 0.2
99.5 8300 7.2 0.3
103.3 8300 3.2 0.2
17.9 2300 12.6 0.2
18.8 2300 4.2 0.3
53.9 4900 6.3 0.1 at 89% throttle
56.2 4900 3.4 4.0 at 100% throttle
56.2 4900 3.4 2.4 at 100% throttle
It looks to me as if one could aim for a 0.2 oxygen reading and get very good results.
The power would probably be just as optimal if one aimed for maybe a 4.0 CO
As for the inconsistencies that Moto saw,
perhaps Moto's tuner's oxygen sensor is not state of the art???
And perhaps many tuner's sensors are not state of the art?????
How do the Oxygen percentages match up to A:F ratio?
I made an error on the second set of numbers I provided. They were all at 89% throttle.
Here are all of the readings for the rear cylinder on the Futura at 100% throttle after tuning pulsewidth to within ±.1 to ±.2 hp of best hp. I'm not going to post HC, CO2 or flux as they are not totally pertinent to the discussion (unless someone asks for them).
rpm ft/lbs hp CO O2
1904 15.97 43.91 4.2 0.5
2353 18.76 41.82 4.2 0.3
2655 24.75 48.90 4.2 0.3
3005 31.54 55.09 2.6 0.7
3306 36.13 57.39 3.3 0.7
3606 39.62 57.68 3.6 0.7
4004 44.01 57.68 3.7 0.8
4407 47.01 55.99 4.0 0.8
4906 55.59 59.48 2.7 1.0
5408 63.17 61.28 4.1 0.8
6007 67.56 59.08 4.7 0.2
6406 75.25 61.68 4.2 0.2
6810 85.08 65.66 3.8 0.4
7108 91.18 67.36 4.1 0.3
7408 95.49 67.66 5.1 0.2
7808 98.69 66.36 4.4 0.1
8309 103.29 65.26 3.2 0.2
8809 105.39 62.86 4.3 0.1
9309 107.60 60.70 3.4 0.3
9807 106.40 56.93 4.3 0.4
You can see that there are only four places out of 20 where .2% oxygen would have been an appropriate target. Then there's the 12.6% CO with .2% O2 example from before...
As far as my gas bench not being accurate, I use an Andros bench, which I definitely consider to be state of the art. See http://www.andros.com.
Again, I consider the correlation between "A/F Ratio" and O2 content to be tenuous at best, but I'm sure someone fom DynoJet could tell you how they consider them to relate.
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I think you guys are over complicating it with regards to gas analysis. Sure O2 is an indirect measurement and can be polluted by air leaks and even the valve overlap could cause air to pass straight from inlet to exhaust. The whole thing is like analysing a fractal image, always more detail the closer you look.
The important thing though is the bottom line and I will outline the results I have got on my two bikes.
I find that the raw sensor voltage can vary substantially especially when tracking the leaner voltages. This is with static conditions - constant throttle, constant RPM, constant ECU output. Tracking to 0.6V I will see many "wild" excursions to 0V or .75V. I can understand that someone trying to be too smart and tracking it closely could get into trouble.
The raw sensor inputs are not the important thing, its the system's response to the inputsthat matters. Even with this seemingly erroneous data, I find that the tracking is stable. The closed loop adjustments will stay within 1% or 2% of the mean value.
I think I need to show another example from the Futura and come at this from another angle to further illustrate my point. For instance 53.92HP and 57.72Ft/Lbs of torque at 4.9K with 6.3% CO and 0.1% O2 at 89% throttle before tuning vs. 56.22HP and 60.22Ft/Lbs of torque at 4.9K with 3.4% CO and 4.0% O2 at 89% throttle after tuning. Another pull with the same after tuning settings yielded the same numbers exactly, but with the O2 content now at 2.4%. If one were to try to tune to O2 content, the target numbers would be in this range (after stagger and ignition issues were adressed): ~.3%-.4% (for large bores) 1%-1.1%(for small bores). You can see that if if the Futura had a closed loop ECU and tried to hit those targets, there would be a serious problem. How does the ECU decide not to respond to sensor inputs? Does it not respond if they are transient? I thought the whole advantage of using O2 was to be able to do just that. Does it not respond if they are outside of certain parameters? If so, it also won't respond when they are legitemately there.
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The conclusion I draw is that there was a fault at least in the exhaust system of one of the Futuras.
What do you think is the reason for this difference? When you have oxygen in the exhaust gas and everything else is ok the engine runs probably rather lean, or what am I missing?
What did the O2 sensor say at these two Futuras, in terms of Lambda or A/F?
It was the same motorcycle. I just pulled up the charts and remembered that the measurements I was referring to were at two different spots before and after tuning, which is meaningful, but less so than if I refer to the same spot . As a for instance 62.73HP and 54.89Ft/Lbs of torque at 6K with 11.4% CO and 0.4% O2 at 100% throttle before tuning vs. 67.56HP and 59.08Ft/Lbs of torque at 6K with 4.7% CO and 0.2% O2 at 100% throttle after tuning. Another example, 99.48HP and 62.92Ft/Lbs of torque at 8.3K with 7.2% CO and 0.3% O2 at 100% throttle before tuning vs. 103.29HP and 65.26Ft/Lbs of torque at 8.3K with 3.2% CO and 0.2% O2 at 100% throttle after tuning. And another, 17.94HP and 39.99Ft/Lbs of torque at 2.3K with 12.6% CO and .2% O2 at 100% throttle before tuning vs. 18.76HP and 41.84Ft/Lbs of torque at 2.3K with 4.2% CO and 0.3% O2 at 100% throttle after tuning. I can find more examples at other throttle position/rpm combos and on other bikes if need be. The before tuning CO numbers do not indicate leanness and the pulse widths were shortened to achieve the improvements, which are as good as it gets, as the tuning was done up to the resolution of the equipment which is ± .1 to ±.2 HP. The EGA only gives percentage of oxygen, not "A/F ratio".
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There's another problem with closed loop systems, and that is the unreliability of using O2 content derived "A/F ratios" in determining whether the correct amount of fuel is being metered in the first place.
The idea is that under perfect conditions (i.e. 100% efficiency), there is some amount of oxygen required to burn a known quantity of fuel with a minimum of leftovers. Unfortunately, that efficiency varies quite a bit. There must be some "average" efficiency then that is used to calculate "A/F ratio" from oxygen content. So, we've arrived at the first problem: There is no direct correspondence between oxygen (or any other gas) content and "A/F ratio". Second, the ideal "A/F ratio" varies from engine to engine and from one rpm/throttle position/load combination to another. Third, I'd like to consider what the goal of tuning is in the first place. Is it to get a particular "A/F ratio"? It's more likely that we would like the engine to make horsepower and be efficient (i.e. get good mileage). Looking at oxygen content has limited use when trying to achieve these ends. However, don't get me wrong, oxygen measurements are actually good for something. Once you have tuned for max power by adding and subtracting fuel, the oxygen numbers can help you to detect an ignition timing or stagger issue. If you go straight to a particular oxygen content, you completely ignore these factors. Even once you've corrected these, the oxygen content can still vary substantially. So it can help to point you in the right direction, but isn't the final arbiter of anything. CO on the other hand can, once a proper value has been established through bracketing, be used throughout a map as a target to set the mixture strength close to optimum for power and mileage. CO is also not the final arbiter of anything, but it tells you much, much more about whether an engines map is in the ballpark than O2. You can hit an oxygen target right off the bat while the engine has the completely wrong amount of fuel and/or wrong timing, whereas with CO, fuel will be close, guaranteed. As an example, there are spots on two Futura dyno charts I have, where the O2 content is 0.2%. One has a CO of 12.6% (this is drowning rich!) and the other has a CO of 3.2% (perfect at this particular throttle position/rpm combination). I'm sure you can draw your own conclusions from this example.
The problem with CO for closed loop injection is response time, and I'm not sure if it can ever be improved enough to be useful.
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go here for the great tuneboy vs. pciii debate that raged on the aprilia forum
http://www.apriliaforum.com/forums/showthr...ghlight=tuneboy
other jabs from Clarkie are here:
http://www.apriliaforum.com/forums/showthr...oy&pagenumber=2
entertaining reading
more TuneBoy/PC debate here: http://www.apriliaforum.com/forums/showthread.php?t=40420
ECU
in Technical Topics
Posted
Amen, brother.
I think that depends on how one defines "great improvements". I think in many cases where an engine has been modified, a tuning link generated map has a chance of being somewhat better than retaining the stock map.