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Old 09-09-2004, 09:53 AM   #1
Undepelo
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Default ECU Learns?? Learns what?


I've often heard the OEM ECU "learns" but I don't really get it. So what exactly does it learn and how does it use what it learns? So what are the things that it learns and what are the benefits?
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Old 09-09-2004, 10:19 AM   #2
serendipity
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It learns the knock threshold of your engine and gas - it will gradually advance timing until it detects the onset of knock, and try to remember about what timing your engine is happy with and your gas allows at various points on the "map" (of RPM and load).

It also learns how your fuel system works, by attempting to maintain a stoichometric air/fuel ratio at low load, and storing the fuel trims it needs to apply to its base fuel map, then applying those trims throughout the map.

The benefits are, if you're in an area that has only 89 or 87 octane gas, your car probably won't explode, but when you CAN get good gas, you can enjoy the benefits of more power.
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Old 09-09-2004, 10:32 AM   #3
Undepelo
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But how do these parameters relate to one's driving habbits? Aren't they dependent on gas, ambient temp., load and stuff like that? The drivers driving habbits are constantly changing to a certain point.
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Old 09-09-2004, 10:45 AM   #4
jaxscuby
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it learns your driving behaviour.
but that would mean you drive freaking nut
everywhere you go. this is not good.

this means it trys to advance timing where it can.
also trys to adjust other maps while staying in the
limits the factory program allows.

Ben
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Old 09-09-2004, 10:50 AM   #5
Zola
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Your driving habits might make it learn faster or slower, but I'm pretty sure what actually gets learned is largely a function of the physical properties of the gasoline you use (see serendipity's reply).

To wit, if you have a lead foot and are in boost much of the time, your car will probably decide on the amount of advance it wants to run in various load sites much faster than if you drive like a grandma and rarely see boost.
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Old 09-09-2004, 10:54 AM   #6
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So it's really learning how to work with the gasoline. So I guess the best thing is to always fill with the same gas all the time. Thanks guys.
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Old 09-09-2004, 12:01 PM   #7
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Here is a link to my description of how a stock wrx is fueled(click me). Below's a little quote about timing(origionally posted by mick_the_ginge)...

Quote:
The WRX timing maps are split into 2. One base map and one IAM map. Depending on what value the IAM is depends on what timing is used. In the IAM timing map the value used is in 16th. Where an IAM of 16 means all the timing value is added to the base timing, a value of 8 for example would mean that 8/16th (1/2) of that timing value will be added to the base timing.

Lower IAM means lower timing across the board is being used.
So with timing, there's a base map which is used when the car first starts. If there's no knock, the iam will advance and the timing being used will also advance until it gets to the maximum ignition advance(16). If the ecu detects a knock, the iam will backstep until the knock no longer occurs. After a while of no knock uccuring, the ecu will try to advance the timing again til it reaches the max iam(as far as I know).

peace
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Old 09-09-2004, 08:06 PM   #8
ilara72
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Will the ECU ever go into a long term knock correction mode? What I mean is, will it always try to aim for 16 or will it ever say there is too much knock and it will never go above 12 (for the sake of argument)?
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Old 09-10-2004, 11:42 PM   #9
bboy
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It seems to mainly learn spark timing, advance or retard, or better yet mostly knock retard. On the STI it "learns" very quickly, or some might say it makes big mistakes repeatedly--choose your perspective. Some might say it's "retarded," or at least a retard lover. I know it's not PC.

Like someone said above it does not learn new "targets" like AFR or degrees advance. It learns within the limits of the target values. The new Hydra from Element Tuning on the other hand, can truely learn in it's auto tune mode with a wide band O2 sensor. You save the new target values. That is f***ing cool!!
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