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  1. #1
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    Yes | No

    How long does the ECU take to "re-learn" after..

    reconnection of the battery?

    This is a follow up post from when I had removed the o2 sensor and posted a pic of the apparent lean condition I had.....

    I have been chasing a "hiccup" or miss right at 3500 rpm for a week now. I swapped o2 sensor, coil, disconnected the vacuum line on the pressure reg, and finally swapped afm's. The measured resistance on the old and new afm's were slightly different - with the newer one reading a little higher in the closed position and rising faster than the old one.

    I was optimistic that this was causing a "lean" condition. However, as soon as I started my test drive, I found the problem still existed.

    I kept driving for a while and noticed that 10 minutes later I could not re-create the hesitation.

    Now I am thinking that maybe the ECU "is" reading the higher ohm readings from the new afm and allowing more fuel (or duration) from the injectors. That is really the only question I have at this time - How quickly that ECU ('89 325i) will adjust to the new readings?

    I gave up for this evening - I hope to confirm that the car is running better for good tomorrow :)

    Don w/ the 3500 rpm blues (and an autox this Sunday!)


  2. #2
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    Motronic 1.0 or 1.1? 1.0 is a straight >M>

    look up table ECU, it doesnt learn.<br>Dave

    86 535i
    84 325e
    01 325Ci
    84 533i parts car
    68 Ford XLGT
    <a target="_blank" href="http://dave.maisenhelder.net/bmw.htm">Dave's BMW Page</a></font></p>

  3. #3
    philv
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    computers don,t learn

    at least the ones in our cars don't. I really don't understand how
    that got started except by someone who knows nothing about computers.
    I mean all the computer in the car does is take signals from the various sensors and it process the data according to the program
    burned into the EPROM. If I'm wrong I'd love to hear an explanation.

  4. #4
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    This is a 1.1 system - does that learn?


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    Re: How long does the ECU take to

    yeah thats what i understand the 1.1 to do. it will compensate for values that are not up to spec. removing power to it will reset it to base line values. the 1.1 also will flash codes with the check light. you have an 88 528e, right?<br>86 528e swarz SO special
    86 528e mostly burgundrot (grape)
    88 528e lach silber (bormann6)

  6. #6
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    I believe it does, but I am not a expert

    <br>Dave

    86 535i
    84 325e
    01 325Ci
    84 533i parts car
    68 Ford XLGT
    <a target="_blank" href="http://dave.maisenhelder.net/bmw.htm">Dave's BMW Page</a></font></p>

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    Called "Adaptive" Motronic for a reason

    Jim Conforti explained this to me once (and he knows a little about the computers in our cars, philv).

    Apparently when the ECU is disconnected, it defaults to a baseline program. After a few minuites of running, it has gone through enough cycles to get feedback from the O2 sensor, etc and applies the info.

    I noticed this when I got really weird feedback on some dyno runs right after swapping the OEM chip for a JimC chip, and back.

    Walt Suman

  8. #8
    philv
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    that makes some sense...


    so some of the info stored in the computer is not static and
    its reprogrammed after the ECU is disconnected from the battery.
    thanks for the insight.

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