ECU

[dlaing]

Moto, any insight about the tuning link map that I posted?

The WOT section is most interesting as it has the A:F ratios.

I suppose if you had more data it would be more meaningful.

[dlaing]

I wrote: "If my belief was correct, then I would rather have had a balanced engine where each cylinder made 40HP, rather than a more powerful engine where one made 39HP and the other 43HP."

Moto wrote: "Sometimes this is done deliberately in order to broaden the powerband."

 

 

Wouldn't this cause vibration and engine wear?

[moto]

Doug Lofgren also wrote this excellent article describing how one O2 Lambda range is not a good indicator of where to tune for power:

http://www.visi.com/~moperfserv/chip_talk.htm

Edit, I am mistaken.

The article does not describe that, but rather how one map will behave differently on two bikes.

If anything it may reinforce the idea that an O2 sensor defined lambda will result in good power.

Check the second chart down between 4750 & 5200, 6500 & 6700, and 7200 & 8500 rpm. In these areas, the engines make exactly the same power with fairly divergent "A/F ratios". Then in the first chart, the same HP is shown in the same areas with the same "A/F ratios". This does reinforce the apparent problems with "A/F ratios", unless one were to argue that the one graph in the second chart was lean while the other was rich and by an amount that coincidentally produced the same power.

[dlaing]

Check the second chart down between 4750 & 5200, 6500 & 6700, and 7200 & 8500 rpm. In these areas, the engines make exactly the same power with fairly divergent "A/F ratios". Then in the first chart, the same HP is shown in the same areas with the same "A/F ratios". This does reinforce the apparent problems with "A/F ratios", unless one were to argue that the one graph in the second chart was lean while the other was rich and by an amount that coincidentally produced the same power.

42315[/snapback]

Yes, that is what I thought at first, but if you go one chart lower, Vern (indicated by the red line) gets a new chip that make him run richer and with more power, albeit only a little more power. and I'll bet his fuel consumption went up! (well maybe not...this is only maximum power per rpm that they are showing.

[moto]

I wrote: "If my belief was correct, then I would rather have had a balanced engine where each cylinder made 40HP, rather than a more powerful engine where one made 39HP and the other 43HP."

Moto wrote: "Sometimes this is done deliberately in order to broaden the powerband."

Wouldn't this cause vibration and engine wear?

Differences in pressures on the tops of the pistons are essentially immaterial when compared to the inertial forces exerted by the reciprocating and rotating masses. With a two into one or a system with a crossover on a v-twin, one cylinder will always be scavenging better than the other at any given time. I should have said not "whether or not", but "how much" in my previous reply.

[dlaing]

Differences in pressures on the tops of the pistons are essentially immaterial when compared to the inertial forces exerted by the reciprocating and rotating masses. With a two into one or a system with a crossover on a v-twin, one cylinder will always be scavenging better than the other at any given time. I should have said not "whether or not", but "how much" in my previous reply.

42317[/snapback]

My bike has a very mild vibration when I let off the throttle. Give it throttle again and the vibration increases dramatically. If the throttle bodies are out of balance, the vibration becomes more apparent.

The V11s produced before they added the front balance pipe are known to have a dip in the power curve and more vibration between 4000 and 5000 rpm.

I have long been suspicious that this was related to the stock exhaust.

I still have the stock crossover, but with Mistral mufflers which results in more peak power, less bottom end and the dip between4000 and 5000 still exists, but it seems with less vibration.

When I had the QuatD (a short 2into 1 muffler)It still vibrated between 4000 and 5000 rpm, but also seemed to vibrate more at lower rpms, too.

I am soon going to put stock mufflers back on to see the difference.

Has anybody noticed a difference in vibration when going to aftermarket crossovers?

[moto]

Yes, that is what I thought at first, but if you go one chart lower, Vern (indicated by the red line) gets a new chip that make him run richer and with more power, albeit only a little more power. and I'll bet his fuel consumption went up! (well maybe not...this is only maximum power per rpm that they are showing.

42316[/snapback]

I'm not sure I understand how the Vern's richer chart negates my point. Can you explain further?

[moto]

My bike has a very mild vibration when I let off the throttle. Give it throttle again and the vibration increases dramatically. If the throttle bodies are out of balance, the vibration becomes more apparent.

The V11s produced before they added the front balance pipe are known to have a dip in the power curve and more vibration between 4000 and 5000 rpm.

I have long been suspicious that this was related to the stock exhaust.

I still have the stock crossover, but with Mistral mufflers which results in more peak power, less bottom end and the dip between4000 and 5000 still exists, but it seems with less vibration.

When I had the QuatD (a short 2into 1 muffler)It still vibrated between 4000 and 5000 rpm, but also seemed to vibrate more at lower rpms, too.

I am soon going to put stock mufflers back on to see the difference.

Has anybody noticed a difference in vibration when going to aftermarket crossovers?

42343[/snapback]

One of the problems with two into one systems and most systems with crossovers on uneven firing engines is that you inevitably have to map the two cylinders independently to get good results. If this is not done, it could contribute to the vibration you are noticing. The Futura with its AF1 h-pipe had very different requirements front to rear. Check out the final maps here:front and rear to see what I mean.

[Cliff]

The Futura with its AF1 h-pipe had very different requirements front to rear. Check out the final maps here:front and rear to see what I mean.

42345[/snapback]

 

Taking the rear map, low RPM. What mechanism would require the injector duration to reduce with increasing throttle?

 

These dips then disappear as the RPM increases.

[JuhaV]

Interestingly large "spikes" in those maps. Are these because of some kind of resonance phenomena in the gas exchange ? Were these really repeatable during the tuning process ?

 

br, JuhaV

[dlaing]

I'm not sure I understand how the Vern's richer chart negates my point. Can you explain further?

42344[/snapback]

The second chart supports your point because Vern's bike, despite being much leaner, makes about the same power as the other bike that runs richer.

But in the third chart, Vern's bike is enriched and his HP goes from about 110 to about 115 which indicates that if we compared Verns' runs in the third chart to his lean run in the second chart, we would find a more similar match to the blue line in the second chart.

 

 

 

second chart:

http://www.visi.com/~moperfserv/charts/chip_t1.gif

third chart:

http://www.visi.com/~moperfserv/charts/chip_t3.gif

[moto]

Interestingly large "spikes" in those maps. Are these because of some kind of resonance phenomena in the gas exchange ? Were these really repeatable during the tuning process ?

Certainly they are repeatable, as they refer to the pulsewidth at that throttle position/rpm and not to a measured exhaust gas content. However, the resultant upper and lower CO limits throughout the map are ~ 2.5 to 5%.

[JuhaV]

Certainly they are repeatable, as they refer to the pulsewidth at that throttle position/rpm and not to a measured exhaust gas content. However, the resultant upper and lower CO limits throughout the map are  ~ 2.5 to 5%.

42380[/snapback]

 

Yes, I understood that these are injection pulsewidth values stored into the ECU. What I was after was that if you make tuning runs, lets say, today and again after a couple of days/weeks, would you have those spikes in the same places and with similar magnitude ?

 

If these are somehow related to resonance phenomena in the inlet or exhaust side, different environmental/engine temperature, air humidity/pressure or any other change (fuel quality) in the system could have significant effect especially on those resonance points.

 

In other words, is it possible that striving towards a very accurate map under some specific circumstances could lead to such a map that it is well suited only to those circumstances. I must add that, at least what comes to Guzzis, I do not really believe that oil/air temp and air pressure sensors together with the original compensation algorithms are doing a perfect job in compensating for the changing situations.

 

br, JuhaV

[dlaing]

If these are somehow related to resonance phenomena in the inlet or exhaust side, different environmental/engine temperature, air humidity/pressure or any other change (fuel quality) in the system could have significant effect especially on those resonance points.

42388[/snapback]

And if say the TPS varied by a few millivolts, the pulsewidth spike could effectively move so that it is doing the wrong thing.

Maybe I am overly concerned, but I don't know how well the TPSs are spec'd.

[moto]

Yes, I understood that these are injection pulsewidth values stored into the ECU. What I was after was that if you make tuning runs, lets say, today and again after a couple of days/weeks, would you have those spikes in the same places and with similar magnitude ?

 

If these are somehow related to resonance phenomena in the inlet or exhaust side, different environmental/engine temperature, air humidity/pressure or any other change (fuel quality) in the system could have significant effect especially on those resonance points.

 

In other words, is it possible that striving towards a very accurate map under some specific circumstances could lead to such a map that it is well suited only to those circumstances. I must add that, at least what comes to Guzzis, I do not really believe that oil/air temp and air pressure sensors together with the original compensation algorithms are doing a perfect job in compensating for the changing situations.

42388[/snapback]

Hmm, I'm not sure how the values stored in the ECU would change from day to day, nor do I have any idea how I would tell, besides copying the tables out of the ECU and having a look at them. If I did that, I assure you they would be the same, as the corrections for ambient conditions do not alter the original values. If you are asking if I would have the same looking map tuning on a different occasion, the answer is very likely no, but not for the reasons you might suspect. Except at full throttle, the ECU is addressing 4 table positions at once at any given time. That means that for a given rpm/throttle position, there is an average of the 4 values taken. You don't tune all 4 values for a given throttle position/rpm though. Instead, you only tune one of the four because the neighboring ones would otherwise be wrong. This means that you sometimes have to use fairly outrageous seeming values for one cell in order to get that average of 4 table positions to add up to the right thing. Since you have to tune from the top down because of this architecture, there is a type of domino effect that can happen in this regard. What triggers it is cells that require weird values in order to counter the effects of reversion, differences in scavenging due to exhaust, etc.

 

As far as the map only being good for the conditions on that day, I assure you that runs are quite repeatable from one day to another. If you need further convincing, look at the CO numbers again. They are quite reasonable regardless of the ambient conditions they might be measured in and will not change radically from one type of conditions to another. Radically different CO numbers are also not required for varying conditions. Whatever slight variation is required, I'm sure the ECU handles just fine, as otherwise my runs would not be as repeatable as they are.