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Old 13th May 2011, 20:56   #76
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Default Re: ECM changed, now what?

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Originally Posted by headers View Post
@Sutripta:
Sir, What IFF the encoder fails, I've seen many encoders fail over time in a different environment and we have accidents [not in a car of course] Plus they are bloody expensive and very sensitive to dirt!! I doubt any automobile manufacturer uses them!!
First, thanks for all the thanks!
When I'm talking of a crank encoder, I mean the tone ring + its pickup together forming an incremental encoder. Or something purposebuilt for a car, like it being embedded in the distributor. Certainly not an industrial encoder piggybacked onto one of the shafts.

I think you are talking of CNC machines. I don't have to tell you about their spares and service pricing policies, do I. But total failure going undetected, and causing an accident is very sloppy work somewhere.

One of the quickest ways to learn is to ask the gurus intelligent 'silly' questions. So we'll wait for the gurus replies to our questions.

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What cost? No cost at all (thinking as an engineer). Adaptation, sir. As a singer, how would you 'adapt' to the percussionist missing a beat? Botch up your song? No, you wouldn't (though it will invariably show up in your expression LOL). It is the same principle that is used there. The 2 missing pulses are a designed event occurring twice in every cylinder cycle, like a programmed pause in music. 2 missing teeth because it is next to impossible for 2 other pulses going missing one after the other. If this happens out of turn, it might cause a small hiccup. If it is constantly happening, it is time to 'limp home' with the Check Engine lamp on. Switching off the engine might be catastrophic (think autobahns).
Was not talking of deliberate designed in missing pulses, but of the possibility of missing a pulse from time to time. Was saying why one needs to resynchronise on every cycle because you said

Quote:
why wouldn't we be able to keep track of what is the current position of each of the components from one signal? (Assumption: engine rotates in only one direction all the time ; ignore back-fire in petrol engines?) The missing teeth only confirm that the signal is 'plausible', and give a certain positional reference. Beyond the first recognizable reference during starting crank, wouldn't everything appear (to the ECU) as a set of repeating events strung out over time?
Correct, but for human understanding only sir, not for programming purposes. Like time and frequency domains for signals (the closest analogy), for the engine controls programming world it is the time domain and events.
And you'll have zillions of maps, one for each rpm?


Megasquirt is a couple of generations behind in algorithms for production vehicles,
Simpler, so much the better for understanding, and getting ones hands dirty.

but may be worth a try (depends on how well the code is commented).
Idea is to write (and comment!) your own code
The website says "MegaSquirt-II™ adds ignition capabilities (including missing tooth crank wheel support)" so one can imagine.
Imagine what?
Since there aren't too many DIY diesel afficionados, I haven't heard of such ECUs for diesels either.
I don't think it will be possible for for a DIY person to program a standalone crdi unit. Requires access to too much proprietary information.


Sir, what I meant was any encoder, whether absolute or incremental, would be pointless since it will add to the cost of controls without giving overriding benefits.
See comment to Headers post.

whereas I as a programmer am not (time domain reference).
Programmers becoming managers:- common.
But senior managers doing hard core programming?
Sir,
This is a really interesting technical thread. With participation of experts. Let us not hijack it, and drive away the gurus.

Regards
Sutripta
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Old 14th May 2011, 10:32   #77
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Default Re: ECM changed, now what?

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Originally Posted by Sutripta View Post
... I mean the tone ring + its pickup together forming an incremental encoder. ...
Quote:
Originally Posted by Sutripta View Post
... See comment to Headers post. ...
Sir, a tone-wheel+sensor arrangement is not an "encoder". An encoder gives the position - relative or absolute - to be read off as a VALUE directly from the encoder, not requiring any further computation from a signal. TANSTA encoder in the engine.

Quote:
Originally Posted by Sutripta View Post
... possibility of missing a pulse from time to time. Was saying why one needs to resynchronise on every cycle ...
Quote:
Originally Posted by DerAlte View Post
... because it is next to impossible for 2 other pulses going missing one after the other ...
A "missing pulse" would just trigger a substitute in software (via a timeout and average time gap of the 2 previous pulses), just like one deals with missing grooms in filmi marriages. The major missing 2 pulses do not "resynchronize" anything (synchronization means something else), they just give a positional reference.

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Originally Posted by Sutripta View Post
... And you'll have zillions of maps, one for each rpm? ...
Err... why should we? There is only 1 map, with RPM on x-axis, and other parameters (more than 3 LOL, so difficult to visually relate to) the injection quantity is dependent on being the other axes. In conventional computing this would be tables (with key indexes) in a database, not 1 table only. The extant value of the parameters result in a desired fuel quantity being returned once in each cylinder cycle. That is further refined by other influences outside the map, and sent to the injection profile handler, which controls when and how much the injector should be opened. That is where injector calibration matters.

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Originally Posted by Sutripta View Post
... Idea is to write (and comment!) your own code ...
LOL one needs to understand the original code (algorithms) to attempt a complete DIY. Even to write extensions.

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Originally Posted by Sutripta View Post
... Imagine what? ...
Capabilities and marketing strategy!

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Originally Posted by Sutripta View Post
... But senior managers doing hard core programming?...
Programming is just the penultimate step in solution creation. It is bad management style if one cannot lead people in providing solutions. If one expects work is done only by issuing commands, that work is quite likely insignificant work. I am sure you do the same as I do.

Quote:
Originally Posted by Sutripta View Post
... I don't think it will be possible for for a DIY person to program a standalone crdi unit. Requires access to too much proprietary information ...
Not at all. As long as one manages to get the mechanicals and the electro-mechanicals, the rest of it is like MPFI with different values, no?

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... Let us not hijack it, and drive away the gurus. ...
Yes sir. Definitely sir. OK sir. <running away AFAIC>
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Old 14th May 2011, 12:37   #78
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Default Re: ECM changed, now what?

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Originally Posted by Sutripta View Post
Could you explain all this in a bit more detail please.
Hi, to get into more details, we may have to discuss about the synchronization process. below is one reason which we cannot proceed further from here. All CRDIs take more revolutions to start the engine. No half crank concept. on of the reason is time taken for getting the sync. how fast you get is one of the topic which is still undergoing research. when start stop systems were implemented, this was one of the challenges that were addressed.

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This is one example of difference in techniques between one injection system vendor and another.
Quote:
Originally Posted by Sutripta View Post
The 3 deg (or is it 6?) uncertainty in determining TDC is something I'm finding astonishing.
Determining TDC is based on the cam and not purely on crank only. Not all calculations is based on the angle. you can have 1 deg resolution in between the 3 deg based on timing.

Quote:
Originally Posted by headers View Post
@Star:
IS there only 1 pilot injection? I heard the famous Quadrajet / MJD / DDiS has 4 injections per cylinder? And thats why the combustion is better than market and it is able to meet BS ?? norms

there will be max of 3 pilots and are time based w.r.t main.

Last edited by star_aqua : 14th May 2011 at 12:46.
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Old 14th May 2011, 16:45   #79
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Default Re: ECM changed, now what?

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Originally Posted by star_aqua View Post
...

Determining TDC is based on the cam and not purely on crank only. Not all calculations is based on the angle. you can have 1 deg resolution in between the 3 deg based on timing.
to get subresolution do you use rpm (and assume it will not chane much in the time it takes the crank to rotate 6 degrees)? Or do you use the analog current pulse coming from the pickup and interpolate on that? Or is there some other method?

Also what typically is the minimum resolution used (and possibly useful) for engine control? I am guessing that at some point the usefulness of the resolution will get limited by noise and inaccuracies somewhere else (practicalities of crank alignment, cam alignment ...)


Quote:
Originally Posted by star_aqua View Post
there will be max of 3 pilots and are time based w.r.t main.
Just for my understanding:

Main => main injection
Pilot => extra injections

Is this correct?



By the way @star, @nitro - do you guys know any book on modern engine control?

Last edited by vina : 14th May 2011 at 16:47.
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Old 14th May 2011, 20:59   #80
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Default Re: ECM changed, now what?

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Originally Posted by nitrogary View Post
for example: say, the injector is supposed to send 10 units of fuel. but in reality it is sending 10.5 units and we know this during the manufacturing testing. so by entering the code, the ECU knows that this injector is sending 10.5 units instead of the desired 10 and suitable corrections can be made.
Thought of sharing this link which I saw today on Youtube, observe closely in the end.



Spike
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Old 14th May 2011, 21:33   #81
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Default Re: ECM changed, now what?

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Originally Posted by DerAlte View Post
Yes sir. Definitely sir. OK sir. <running away AFAIC>
Great. All our discussions/ debates/ disagreements will have to wait till this thread has died.

Quote:
Originally Posted by star_aqua View Post
Hi, to get into more details, we may have to discuss about the synchronization process.
Please do.

Determining TDC is based on the cam and not purely on crank only. Not all calculations is based on the angle. you can have 1 deg resolution in between the 3 deg based on timing.
Was not talking of interpolation, but of basic accuracy of index mark. Any ballpark figures?
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Old 16th May 2011, 22:46   #82
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Default Re: ECM changed, now what?

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Originally Posted by Sutripta View Post
Great. All our discussions/ debates/ disagreements will have to wait till this thread has died.



Regards
Sutripta

well the thread is dead now, may be at least you guys can add something.


Meanwhile I found two books : "Uderstanding Automotive electronics" by Ribbens and "Automotive control systems" by Nielson. The first one gives a broad overview and the second one gives a lot of mathematical modelling and detail.

Can you guys comment on these two? I'm trying to get the Bosch manuals, but tough luck so far.
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Old 16th May 2011, 23:02   #83
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Default Re: ECM changed, now what?

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Originally Posted by vina View Post
well the thread is dead now, may be at least you guys can add something.


Meanwhile I found two books : "Uderstanding Automotive electronics" by Ribbens and "Automotive control systems" by Nielson. The first one gives a broad overview and the second one gives a lot of mathematical modelling and detail.

Can you guys comment on these two? I'm trying to get the Bosch manuals, but tough luck so far.
Hi,
Let's give Star_A, Nitro, Spike and others a few days!

The Bosch References (not the yellow jackets) are good, but Heywood they are not. The 8th edition, (English) of the auto handbook should come out this month. In which case the 7th edition should be discounted. (You can also pick it up from the net.) (I'm old fashioned. Prefer paper)

Regarding "Automotive control systems", the one I've got is by Kiencke and Nielsen. If you are talking of that, then as point of reference, the Bosch books are nowhere as theoretical. Meant for a different audience.

Please remember, these are a laymans views.

Regards
Sutripta

Last edited by Sutripta : 16th May 2011 at 23:09.
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Old 17th May 2011, 00:28   #84
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Default Re: ECM changed, now what?

Quote:
Originally Posted by Sutripta View Post
Hi,
Let's give Star_A, Nitro, Spike and others a few days!

The Bosch References (not the yellow jackets) are good, but Heywood they are not. The 8th edition, (English) of the auto handbook should come out this month. In which case the 7th edition should be discounted. (You can also pick it up from the net.) (I'm old fashioned. Prefer paper)

Regarding "Automotive control systems", the one I've got is by Kiencke and Nielsen. If you are talking of that, then as point of reference, the Bosch books are nowhere as theoretical. Meant for a different audience.

Please remember, these are a laymans views.

Regards
Sutripta

If you are a layman, I wonder how many are experts.

I've got the Kiencke and Nielsen.

On Bosch, I wasn't talking about the handbook, I don't think that will have any details about engine control. I was talking about "diesel engine management" and "gasoline engine management" - both specific engine books.

I guess having the handbook wouldn't hurt either.
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Old 17th May 2011, 08:02   #85
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Default Re: ECM changed, now what?

^^^
Was referring to the Bosch reference books, of which there are four, + the 'blue bible', aka Bosch Auto Handbook.

Regards
Sutripta

PS. You mean these?
Attached Thumbnails
ECM changed, now what?-books.jpg  

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Old 17th May 2011, 08:16   #86
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Default Re: ECM changed, now what?

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Originally Posted by Sutripta View Post
Hi,
Let's give Star_A, Nitro, Spike and others a few days!

The Bosch References (not the yellow jackets) are good, but Heywood they are not.
I have some info which comes under IPR so cannot share here, Heywood I believe is a pretty good book for fundamentals, what do you say?

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^^^
Was referring to the Bosch reference books, of which there are four, + the 'blue bible', aka Bosch Auto Handbook.

PS. You mean these?
I have a soft copy of the Bosch Handbook, not sure if it is the one you are referring to, didn't find anything concrete there, yes it is good for basics.

Dada, you have all these books with you? No wonder.

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Old 17th May 2011, 08:32   #87
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Default Re: ECM changed, now what?

^^^
Hi,
Pratheesh, why don't you and the other professionals make a list of books, with a short synopsis, which should be there on every technically aware TBhpians desk. This topic has been visited before, but never went anywhere.

Regards
Sutripta
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Old 17th May 2011, 08:56   #88
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Default Re: ECM changed, now what?

^^ Dada, I will do that, tell me the topics. I am not a Calibration / Control systems guy, so may have limited resource w.r.t them, others I can see. I have huge references for SAE papers, tell me if you guys are interested in specific topics, I will give the Paper Numbers.

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Old 17th May 2011, 09:37   #89
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Default Re: ECM changed, now what?

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well the thread is dead now, may be at least you guys can add something.
I dont think this thread is dead - its just like the other threads which become dormant at some point in time.
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Old 17th May 2011, 10:34   #90
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Default Re: ECM changed, now what?

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Originally Posted by Sutripta View Post
^^^
Was referring to the Bosch reference books, of which there are four, + the 'blue bible', aka Bosch Auto Handbook.

Regards
Sutripta

PS. You mean these?
Yes sir, those books. I couldn't find the two Diesel engine Management and Gasoline Engine management.

May be will have to look harder.
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