The 4AGE ECU is a pretty incredible unit and not something most people give due credit to. I've been trying to learn as much as I can about it regarding it's "intelligence" and I thought I'd share what my good friend Nitin has been telling me. Nitin has been working towards getting his mechanics certificate for a while now, and he's one of the few guys that seems to really take to the electronics side of the business as well as the usual pulling wrenches bit.
Here's what I've learned, put into easy to understand terms...
The 4AGE ECU is an adaptive or "learning" unit. The ECU will take the information from the many sensors in the car, match that to the way the car is being driven, and work out the best way for everything to work/fire/run to keep everything as efficient and smooth as possible.
Whenever any engine electrical work is done (moving sensors, making adjustments, etc.) it's always a good idea to reset the ECU. You can do this by either disconnecting the negative terminal from the battery post for a couple minutes (or more depending on how cold the car is), or removing and reinstalling a fuse in the kick panel near the driver's feet. Doing this gives the ECU a chance to forget what it's learned in the past so to speak, and start with a clean slate. If you do this it will seek out fresh readings from all those sensors and use those to make the engine run smoothly, instead of piling the new readings on top of the old bad ones and trying to get a good working operation from the combination.
So that's the engine/sensor side of teaching the ECU. You adjust all the sensors and stuff within spec, then the ECU learns what it needs to automatically. Pretty easy.
But the other part of teaching the ECU comes into play when the car is actually being driven. The ECU will need to know the answers to questions like: How do the sensors react when the car is accelerating? Decelerating? Coasting? What's the best way to manage spark in those situations? What about timing? etc...
When the ECU learns the answers to these questions, it's hoping that YOU the driver will know how to properly train it, which is something I've understood for quite sometime, but never knew exactly HOW I should drive the car so it learns what it needs to in a proper way.
This is what I've been instructed to do:
Find a nice, long, and hopefully deserted road. After getting the car up to normal operating temperature, and after resetting the ECU, drive the car up to 60km/h and then let the car slow down to 30km/h WITHOUT touching the brakes. I assume you should leave the car in gear. Once you hit 30km/h, take the car up to 70km/h and then once again let it slow to 30km/h. Repeat this procedure for 80, 90, and 100km/h. Doing this should give the proper and consistent readings it needs in order to decide how to run the engine in the most efficient way, and apparently this works for most EFI systems used by pre-96 vehicles.
If anyone has anything to add to this, by all means please say something. I haven't had a chance to teach the ECU in my hatchback yet since I JUST fixed all it's problems about an hour ago, but I'll be doing it first thing tomorrow.
"...apparently this works for most EFI systems used by pre-96 vehicles."
interesting... I would think tho that its adaptive to some extent, that the structured "teaching" part wouldn't make much difference given that its not typical behavior of day to day driving.
...i could be totally wrong tho, perhaps it is only meant to establish a base line of sorts.
I'd like to find out more ... keep us updated!
great potential sticky material
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Last edited by BLUEMEANIE; 06-30-2005 at 01:27 AM.
There's a 3 page discussion on this topic at dorikaze.com, apparently the 4AGE ECU is adaptive but yeah.. it will establish a set line to base its maps. Then it adapts to people's driving. I'll get some more quotes, in the meantime somebody sticky this one.
It would probably be best if you just accelerated gradually and normally, not too fast, not too slow. Let the car learn the way it work in ideal situations first, then after you train it, bag it! Bag it rotten baby, yeah!
As for how long to keep it at the different speeds, I believe all you have to do is hit that speed then back off.
Question: So by this theory, the ECU is not constantly learning, adjusting & adapting in immediate driving conditions, it has it's first run than runs off those specific sensory inputs till it's reset?
Answer:
Quote:
yes and no...from what I understand, it does constantly learn, but by resetting the ECU and "teaching it" using the described method, you lay the groundwork or foundation that the ECU will refer to and base changes off of during drives after that time.
Kind of like a person comparing notes
"okay, this is what i was taught to do...and this is the situation I'm now dealing with...now i have to make a comprimise between them..."
"And they did it with innovations like an 8-bit microcomputer that adjusts the fuel injection for clean and mean running under all conditions."
This statement leads me to believe that it resets itself to a factory set baseline running condition after it's turned off for the next start given there's no malfunction codes stored in its memory. If your O2 sensor is cooked and your timing is a little wackey, it'll do its best given what it's being fed info-wise each and every time you start and run the car provided the ECU is not malfunctioning. It will run the engine even with big troubles going on in it's backup running mode (so you can drive to the shop/dealer before it fully has a meltdown).
I agree this is excellent practice when "real" work has been done involving major changes. But at the same time I also think it will do its intended job, learn new inputs and adjust fuel accordingly & quickly with a regular civilized drive around the block till it's fully warmed up...I could be wrong.
response
Quote:
There's no doubt that the ECU will do it's job regardless of being trained or not, but if you want to maximize the efficiency and potential of your engine, doing the 5 min training procedure is probably worth it.
What brochure do you have? The '85 Canadian Corolla brochure or something else? Have a pic or a scan? I'm curious if that same excerpt is in one of the brochures I own...
so could this solve constant overheating problems. my car would overheat, when i have the ac running but only during the peak hours of the day, like at noon. but at night if runs just fine.
so could this solve constant overheating problems. my car would overheat, when i have the ac running but only during the peak hours of the day, like at noon. but at night if runs just fine.
Turned out the car's previous owner had done some very stupid shit with radiator fluids. Apperantly "Do not mix" wasn't clearly understood.
Had it routed out. Works fine. Except for the bit when the shop forgot to solder about four fucking inches back together.
Blah. But that's shops around here for you. At least since it was a Toyota dealership shop, they made it right without trying to rob me blind, which will probably get them some donuts courtesy of me sooner or later.
That, and they give really good diagnostic advice when I pay for it. :>
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MIGS.
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