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Thread: Engine Code P2096 (fuel trim code on Mirage with custom header)

  1. #21
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    Quote Originally Posted by foama View Post
    To start with, the FSM is taylored to the needs of servicing, not so much for explaining things, although it does provide some info. Mitsubishi is a huge group of organisations that makes just about everything from integrated circuits, airconditioning, jet airplanes, satellites, and everything in between, you name it. The automobile section is tiny in comparison. The R&D in Mitsubishi electronics has huge resources, and the extremely high level of very sophisticated electronics in these cars is one of their best aces.
    Because of being foremost in engine electronics, most details are confidential, and it is hard to get more than general information, they rightfully want to keep their secrets.
    What we definitely know are details taken from the FSM. There is also a russian forum mainly about ETACS that sheds some light on various details. Its like maths. If you now what the equation is about, what results are expected and see most figures, you swiftly get an idea of whats missing.
    I do understand that most aftermarket tuners understand only a small percentage of how any particular ECM works, and what its capabilities actually are.

    I have really not made any reference to the FSM. Instead I have spent most of my career working with computers, and usually working at the level of system software and assembly code. I do have know ledge of some ECMs, specifically Ford ECMs from cars and trucks produced in the mid 1990s, extending just into the OBD2 timeframe, and have detailed knowledge of how a few of these systems (designed in the late 1980s) are supposed to work.

    The amount of CPU power available to automotive electronics has increased hugely since that time, and a move to higher level languages, and the reduction in cost of the hardware has certainly led to much larger code and data sizes. It is also apparent that many automotive functions are now controlled by automotive computers, that were not done that way decades ago.


    Quote Originally Posted by foama View Post
    We know that the ECM/ECU controlling the engine works with much larger EEPROMS than with other makes.
    Controlling the Mirage engine? What other makes are you comparing to?

    Quote Originally Posted by foama View Post
    In the ECM of cars made in year 2000 we had maybe a total of a half a dozen points stored in memory, and everything in between was result of sensors for correcting. These worked with lambda sensors and a huge time-lag, in addition to their very limited accuracy. If engine operating conditions were not constant, and that is normally the case, for example you were accellerating or slowing down, computed conditions were miles off from actual, and emissions were bad and economy also.

    In the ECM of these cars we have 8bit technology for the number of stored tables, and it seems there is also 8bit numbers of information sets (256!) stored within each table. We also have electronics capable of recognizing and switching between tables in realtime in milliseconds. This is light years from what was normallity in 2000, and is much more sophisticated than many other makers today. It makes these cars easily pass emissions and yet be economical at the same time. I have tried finding detailed info, but nill success.
    Based on my own experience, I would actually dispute this. By the 1990s, ECMs were 16 bit, and used 10 bit analog to digital converters, stored data in 16 bits where it was required and 8 bits where it was not. Lookup tables were indeed often using 8 bits, but could do linear interpolation in 16 bits where required. By the early 2000s, 16 bit lookup tables were seen more often. CPUs were running at 25MHz and
    were able to address 1MB of code and data, although almost always used no more than 216K of ROM and 16K of RAM. That's for a system designed in the 1990s for OBD2 and only retired in 2006.

    So what you describe as being normal in 2000 was in fact obsolete by a long was in the 1990s.

    You talk about switching between tables in milliseconds. If we had a 6 cylinder engine running at 6000rpm, then that is doing 100 crank revolutions in one second, or one crank rotation in 10 mS. Its crank speed might well be measured by a toothed wheel with 36 teeth
    so each tooth creates an interrupt every 280 microseconds or so. If it's knock sensor triggers, it might well be aiming to retard the timing before the next spark event and these happen every 3 mS.

    So my point is that making things happen within milliseconds is way out of date. A millisecond is an eternity in the capability of today's ECMs.

    So I do not doubt that an O2 sensor could sense exhaust mixtures all cylinders of the Mirage 3 cylinder engine, and I do not doubt that the ECM is fast enough to process mixture reading from individual cylinders IF they are presented to it, but I remain politely skeptical that today's O2 sensors are fast enough to provide that signal.

    I am open minded about this, feel free to change my mind.


        __________________________________________

        click to view fuel log View my fuel log 2014 Mirage ES 1.2 manual: 46.0 mpg (US) ... 19.5 km/L ... 5.1 L/100 km ... 55.2 mpg (Imp)


  2. #22
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    Quote Originally Posted by mpaton View Post

    So I do not doubt that an O2 sensor could sense exhaust mixtures all cylinders of the Mirage 3 cylinder engine, and I do not doubt that the ECM is fast enough to process mixture reading from individual cylinders IF they are presented to it, but I remain politely skeptical that today's O2 sensors are fast enough to provide that signal.

    I am open minded about this, feel free to change my mind.


    This is the core question about individual fuel-air trim being possible. I'll try to find out more about that.



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