4AGE 16v. Does ECU self adjust?

[Adamal]

There has been much talk before about ECU's, and if they build up a map of sorts over time.
For example, I have seen here and elsewhere, people reporting that their car isn't running quite right or idles a bit rough. People often suggest that they unplug their ECU/battery for about 15 minutes and see how it goes after that.

I have discussed this with RomanV, and it seems that maybe newer ECU's do, as he has noticed a difference in resetting his, and just leaving as is.
Are older ECU's the same though?

I ask this, because I have a key which disconnects one of the battery terminals in my car.
I've been getting poor economy from it and suddenly it hit me... Could that possibly be the problem? I'm essentially resetting the ECU every time I stop the key and disconnect the battery.

That, of course, is IF my ECU does build up a map of sorts over time.

Is there anyone who knows if this is fact or fiction?

The ECU in question is an 84 4AGE Bluetop. It's an NZ new ECU, however the only differnce should be that it doesn't have input for an oxygen sensor. I'm not sure if that would make a difference or not. I'm guessing that it could, as it wouldn't be able to read how rich/lean the combustion would be.

Any info would be appreciated.

[Dragger_Dan]

Sorry I can't help with more fact, but I will tell you a few things I have noticed. Firstly that when I have unplugged my ECU and let it reset it _seems_ to run a little richer, especially at idle, but then comes back to normal by the time I have taken it for a quick drive. I have been able to notice this because sometimes it even backfires when I have just reset the ECU.

The other thing I'm told - again, no idea if this is fact or not - that the ECU will retard the timing once you have reset the ECU, and advances again when you have 'warmed it up'. I thought this was mainly a thing with turbo cars with knock sensors, but I've been told it happens with 4AGEs, so no idea.

[slighty_sykotic]

I remember reading somewere that a certain gen of 3sge/te was one of the first toyota ecus that had any form of self learn....

Meaning that anything before that would also be guarenteed to not learn.

I really don't believe it, but I am only going on what people say/i think. Not any evidence.

So really this post isnt saying much

*waits to hear other replies*

--Sykotic

[Adamal]

Sorry I can't help with more fact, but I will tell you a few things I have noticed. Firstly that when I have unplugged my ECU and let it reset it _seems_ to run a little richer, especially at idle, but then comes back to normal by the time I have taken it for a quick drive. I have been able to notice this because sometimes it even backfires when I have just reset the ECU.

Hmm... Thats something I've notice too, Dan. I have a lot of popping at idle until she warms up. I mostly travel too and from work, usually 30 mins there, an hour back, then shes unplugged, so doesn't get much of a workout.

[RomanV]

Bear in mind that cars generally run richer while cold, which may cause the popping etc.

Think of the computer technology that was available in 1983/1984 when the first 4age was conceived....

And then compare that, to the every day tech in 2002 etc.

I dont doubt that this has made ECUs smarter in a lot of regards.

I recall reading that some ECUs have batch firing injectors (eg. 2 at a time )
that the ECU can only really interpret the TPS as 70% open and up, and less than that, and various other rangy things that dont come to mind right now.

Which were all due to constraints on the amount of memory that ECUs had at the time.

However I have no idea to what extent this affected toyotas.
I know that 5SFEs have a cheap and nasty ECU, with batch fired injectors etc... And that was a 90s engine.

[RomanV]

Also, a few of the articles here:
http://www.autoshop101.com/autoshop15.html

mention the learning/tuning capabilities of toyota ECUs.

Which store a long and short term map for ignition, fuel etc, and varies them based on info from the sensors.

However it is unclear whether this applies to all ecus (doubt it) or just more modern ones, (likely) or just the ECUs in fancy cars/engines (possible?)

Adamal, I wonder if there's merit in fitting a J spec ECU, and fitting an oxy sensor too? It might be the answer to your fueling woes.

I doubt a bluetop 4age ecu is going to cost you the world, or be hard to find, it might pay for itself with reduced gas consumption.

[matt dunn]

For an ECU to self learn, first it must know if it's too rich or too lean,

and if your car is NZ new with no oxy sensor then how will it know???


I very much doubt it will have any learning ability at all.

Matt

[Dragger_Dan]

Actually I'm with Matt on this one, I just didn't read the bit about a lack of oxy sensor. I guess it could be a timing thing

[RomanV]

It still has a knock sensor (I think?) So it could still potentially advance or retard the ignition based on knock?

Well that's an assumption on my part, I dont know if they've got a knock sensor either.

Regardless, I doubt that ECUs were that advanced in 1983... I mean that's at the time where 128kb of ram would probably cost you a few grand, and NASA had less processing capability than my cellphone.

[Dragger_Dan]

Sorry, bluetops don't have knock sensors. They mainly show up on the turbo cars of that era, don't they?

[RomanV]

Well there you go... There's no way it's going to learn anything, without either a knock sensor or oxy sensor.

I'm not sure about other cars of that era, the only car that old that I've owned is a KP starlet, and the 4K is no technology showcase.

[Adamal]

For an ECU to self learn, first it must know if it's too rich or too lean,

and if your car is NZ new with no oxy sensor then how will it know???


I very much doubt it will have any learning ability at all.

Matt

Yea, thats what I was wondering.

[sergei]

As for technology, they still use 30 yo technology on new cars. Microprocessors have been arround for quiet a while, and the limit what ECU can do is not in the hardware (or technology of it) but in programing, the firmware what they run determines ECUs capability of learning. Obviously it needs to have some sort of feed back hence knock sensor, and oxygen sensor.
NZ new cars run fake signal for Oxygen sensor, so it fools computer thinking it is running in optimal range. You still can have ignition learning capability (that is if they still got knock sensor).

[Adamal]

So I know a 4AGZE has a knock sensor, but does the Bluetop?

[KinLoud]

Well there you go... There's no way it's going to learn anything, without either a knock sensor or oxy sensor.

Yes it could... it just has a microphone on the dash that picks up the driver cursing the fuel economy. When it hears this, it richens the mixture a bit more!!!
Hah

Ken
Ham
021 408 863

[Adamal]

Ahhhhh.... Theres my problem all along! I haven't been verbally letting my disappointment in the cars economy known! I've always just cursed at it in my head!

Thanks Ken, I'll give it a try

[Mr Revhead]

remember any "learning" ability is within tight limits....

to all intents and purposes the ecu reset is more internet myth

[Ako]

No its' not

I've seen it work a treat on a few cars. Some of which were datalogged, and you could physically see the results happening, so it wasn't just a "bum dyno" feeling of this is faster - we actually proved it.

For example, on a mates early VR4: 20psi + avvy = around 15deg advance (for example, I can't remember exact numbers).

Reset ECU - Started running more advance. Without resetting it, nothing changed from putting av in there, we were actually out to see what difference a reset actually made to anything.

I've also seen it fix problems on a multitude of cars (AFM faults, boost issues in subarus etc etc). Its the first port of call whenever I have a weird little gremlin with my own cars, and half the time it does help matters. When it doesn't, the problem is generally physical, rather than electronics being munty.

Also bear in mind that ECU's DO build up a small memory of sorts. I know with mitsis at least, the 02 sensor input, while being primarily being used to determine the cruise fuel trims, also puts an offset of sorts into the closed loop / full throttle parts of the fuel map. Changing the 02 sensor has netted more power (after a period of time) on a few cars I've personally seen. When you have no O2 sensor or a shagged one, the ECU reads assumes the worst, and you run rich. Then when you're at high load, you're richer than ideal, and lose power.

So there

[Mr Revhead]

remember any "learning" ability is within tight limits

build up a map of sorts over time.

they dont adjust themselves instantly.....

and clearing faults and "limp" mode......

for instance no where for any fault, part replacement, recall, upgrade etc do any toyota manuals instruct the tech to reset the ecu. except for clearing codes

[Chickenman]

As far as I can tell after having a good dig around a year ago, subaru and Mitsubishi seem to benefit from an ecu reset if you change octane etc, Toyota didn't implement anything more than a very small adjustment range if anything at all, as revhead said, it may be there but it has a minimal impact as it operates within a very small margin.
Newer cars should be different though..?