Resetting/Learning ECU

Discussion in 'Modifications And Maintenance' started by Hallywood, Apr 27, 2006.

  1. Hallywood
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    Hallywood Well-Known Member

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    I got this off NASIOC, anyone use or try this?

    Posted by Shiv:
    Just a little trick that has been shown to accelerate the factory ECU's ignition timing learning process.

    Background: There is something called "Ignition Advance Multiplier". It represents, by some complicated algorithm, the average learned positive knock correction applied to the ignition maps. It's represented in 1/8th degrees increments. 1 being the lowest and 16 being the highest (1/8 to 2 degrees in absolute terms).

    The "happier" (knock free) the car is, the higher the number will be. Conversely, the lower it is, the more knock prone it is. This number, after ECU reset ore ECU swap defaults to 8 and usually creeps up to 16 (if well mapped) through normal driving. Depending on driving characteristics, this can happen within a few hours or a few weeks. Well, here's a way to make it happen in about 5 seconds ....

    First: With the car fully warmed up, reset the ECU. This can be done by killing power the ECU or by simply pulling off the neg. battery terminal and pressing the brake pedal for a couple of seconds.

    Second: Drive to a nice open road without traffic. Don't go on boost until you get there. Put the car into gear (3rd gear works the best) bring the revs up to 2600rpm. Push the go pedal down slightly so boost stays right around 2-4psi. You will need to MAINTAIN 2500rpm and 2-5psi for approx 5 seconds. You can do this by left-foot braking gently as to prevent acceleration. During these few seconds, the advance multiplier (which you can't see so you'll have to trust me) will go from 8, to 12 and then to 16. Works like a charm. And on our reflashed ECU, is worth an immediate 10-20 horsepower

    In an attempt to save a lot of dyno time between reflashes (when the advance multiplier resets itself), I do this little trick after every reflash. In a typical dyno session, it's not unusual to reflash the same car up to 5 times. On the dyno, all I need to do is tell the dyno to hold revs to 2600rpm. Then I just lay on the throttle until I see a few psi of boost... Bingo!

    Warning: This little trick artificially speeds up the learning process. This is only a good thing if the re-mapped ECU is mapped properly. If there are trouble-spots where knock is present, this trick will make it even more present. So be careful!
     
  2. Steve-o
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    Steve-o Administrator Staff Member

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    No. There is no need to. It's a way of speeding up the learning process after a reset... but if you have been driving your car and it hasn't been knocking it is already where it should be. The time I have had playing with the protuner/street tuner the ecu learns very fast just being driven normally. I can put a new base map on and by the time Shane drives it 5 blocks to an open road the dynamic advance is already maxed out.

    Some decent discussion on the topic later in this thread:
    http://www.mnsubaru.com/forums/showthread.php?t=11316