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MyECU >> MyECU Advanced usage >> O2 Flags https://www.cajinnovations.com.au/forum/YaBB.pl?num=1346079009 Message started by Bobd on 08/28/12 at 00:50:09 |
Title: O2 Flags Post by Bobd on 08/28/12 at 00:50:09
OK, I need a bit of help understanding the 'flags'.
I understand the MyEcu running closed loop uses the lamda sensor to detect how much oxygen is left in the exhaust gasses and that too much oxygen indicates too weak a mixture as we have not had enough fuel to react with the remaining oxygen, we can get more power by adding fuel to utilise this available O2. The MyEcu adjusts the fuel automatically to keep near the ideal air/fuelmix (providing the map is reasonably accurate. In the Map we state what voltages from the lamda sensor equate to which air/fuel ratio. We then have the 'flags' table telling the MyEcu which particular ratio we want for each cell. What I don't understand is how we assign the flag numbers, how do we know what air/fuel ratio we want for each cell? Obviously as we have differing flag values we are not just setting it at the stiometric ideal. It seems we very accurately get the fuel system to inject an amount of fuel based on rpm, throttle, air pressure etc but then introduce these flag settings. |
Title: Re: O2 Flags Post by YaBB Administrator on 08/28/12 at 07:17:32
Have a look at this page for an explanation of the map - http://www.cajinnovations.com/MyECU/maps.htm
Basically you have an array of 8 voltage targets, the index into this array is [0-7]. The flags table contains the index for that cell. so if your flags to O3 you will be selecting the 4th entry in the targets table. |
Title: Re: O2 Flags Post by Bobd on 08/28/12 at 07:22:09
Yes, I have read that. How do you know which value to select?
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Title: Re: O2 Flags Post by YaBB Administrator on 08/28/12 at 07:31:28
That's what you need to determine. I don't have the data for the sensor and you can basically use what ever sensor you want.
The base map you have has reasonable values from my Breva as a start. Modify as you see fit. |
Title: Re: O2 Flags Post by Bobd on 08/28/12 at 07:43:24
At the moment I am using the SPORT.ECU map set +5% across the whole map with a running TPS of 101 (95 with the engine stopped). The bike runs well, a bit slow to start but great in the mid range.
Is it the case that one either alters the map in an experimental fashion to get good running or use the Optimiser with closed loop and Autotune again setting the O2 targets experimentaly. On the last fairly long run the Optimiser did not make any changes to the map in Autotune. Am I wrong in thinking it will update automatically if it finds itself in a steady 'Mon' state or do I have to tell it to save the change - a bit risky while riding. At the end of the run I just turned off the bike ignition, should I have exited Autotune before stopping the bike? |
Title: Re: O2 Flags Post by Luhbo on 08/28/12 at 07:44:10
I think you're asking what value is good for driveability or for power and in what range/cell, aren't you?
In that case: wellcome to an endless playground :) Theoretically you can choose from L=1.2 for best economics down to L=0.8 for best power. Log your driving to see how you drive, where in the map you are doing what, and then guess where you need best power and where you can try to reach better efficiency. I started with L=0.93 for the entire map, tried one similar with 0.96, actually I have one with values from .89 to 1.0 - all in all with very similar results. Maybe that next week I'l try one real rich, maybe not. That's why I have this unit instead of the Weber 15M. Start with one of the given example maps in the download section for instance and look how these contributors dealt with this question. In this context it would be a real 'nice to have' if we could switch via Optimiser for instance between 2 maps at least. This would make 'playing' a bit easier and more straight ;) . But how said a German BMW/Mini commercial once (in English): 'Pussies Go Straight!' It gave a little trouble then as most people translated 'Pussies' differently ;D Hubert |
Title: Re: O2 Flags Post by YaBB Administrator on 08/28/12 at 07:48:00
My Sport map is set for an LC1 and would be totally inappropriate for the standard Guzzi sensor. You should take the tables from me Breva map.
If that's what you have you're lucky the optimiser did nothing. You have to make sure the bike is running correctly with closed loop first before trying autotune. |
Title: Re: O2 Flags Post by Bobd on 08/28/12 at 07:54:16
I used the Breva voltage settings you kindly sent me a few weeks ago.
I suppose what I don't understand is how you decide what target lamda you are looking for in each cell. I imagine this is a general EFI matter rather that MyEcu specific. |
Title: Re: O2 Flags Post by sign216 on 08/28/12 at 23:10:04 Bobd wrote on 08/28/12 at 07:54:16:
It's a little like asking what beer is best. Everyone has a different idea what's best for their specific bike, regional fuel variations, and riding style. Tuning on a dyno could give objective numbers and end the argument, but most of us merely fiddle away, tweaking the map to reach some kind of perfection. Joe |
Title: Re: O2 Flags Post by Bobd on 08/28/12 at 23:39:58
Yes, a dyno is the answer but I need to fully understand what is happening first. In the old days we just tinkered with the carb to get a nice spark plug colour - I suppose we are now telling the ECU what colour we want.
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Title: Re: O2 Flags Post by sign216 on 08/29/12 at 11:18:05 Bobd wrote on 08/28/12 at 23:39:58:
A lack of understanding never stopped me. |
Title: Re: O2 Flags Post by YaBB Administrator on 08/29/12 at 13:30:37
The biggest mistake people make is changing something to what they think it should be with no other reason.
Always let the symptoms of the bike drive the changes. |
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