4AGE ECU: Reset and Teach
The ECU for the 4AGE 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 is a Toyota technician, and he's one of the few guys that seems to really take to and understand the electronics side of the business as well as the usual wrench pulling aspect.
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 Nitin suggested:
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.
Any questions or comments, please feel free to ask!
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