How the 4A-GE ECU works

[JMR_AW11]

phatBob Wrote:

JMR_AW11 Wrote:Just added a quick 3D graph to my web page to show ignition timing in degrees BTDC.

Have you got a URL for that please? I had a look at your site and couldnt find anything specific. I can patch it into the VEMS ecu tomorrow. I will be moving the 20V onto coil on plugs in the next few days so to run on a 'proper' ingition advance table would be really good. Even with bad accel enrichment setup the engine feels really lively and responsive, although it can take a lot of advance it seems to be good with only 25degrees total advance. I'm a Honda man with Nissan leanings but these Toyota engines are ver impressive.

It's the same link. I added the 3D graph at the end of the article (page 2)
http://www.jmross.freeserve.co.uk/part3p2.html

The ignition timing for your 20V engine could be very different though.

You should really only play with your timing with the aid of a knock sensor monitor.

i.e. you should listen for signs of knock as you advance the timing to try for more power.

It would be a shame to damage that wonderful 20V engine with too much advance!

[JMR_AW11]

Denmark Wrote:This is great,

can you make a price on what it would cost if the ECU is shipped to you,and then you modified it!,
Put in the OE maps again,but on the the new chip,so it can be modified!.

The cable needed to connnect to the laptop,and the program!.

This is what we all need,but a Q?.

can the map sensor get changed and the maplimit,so the car can be boostet, and still use the oe ECU, or would it then be better to use MS, or some other ECU

Regards,
Skassa

I'm getting a batch of ECUs built now but these are only for the UK 4A-GE ECUs.
If these sell well then I will try and get hold of ECUs from other countries.

You can change the map sensor as long as it has a similar electrical interface but I would advise you go for an ECU with a knock sensor function if you are going to fit a turbo. The basic UK 4A-GE ECU does not have a knock sensor.

[NoHachi]

Or just add a separate knock retard unit..You really don't want the ecu controlling knock unless you are running an Ion sensing setup. Basically you just want to tune the engine to a safe margine under the knock threshhold, and then have a sort of limp home function to cut in whenever it does pop up. Diagnose the problem, solve it and go back to std running mode..

I doubt whether the stock ecu will be able of handeling positive MAP. The sensor doesn't.

[JMR_AW11]

NoHachi Wrote:Or just add a separate knock retard unit..You really don't want the ecu controlling knock unless you are running an Ion sensing setup. Basically you just want to tune the engine to a safe margine under the knock threshhold, and then have a sort of limp home function to cut in whenever it does pop up. Diagnose the problem, solve it and go back to std running mode..

I doubt whether the stock ecu will be able of handeling positive MAP. The sensor doesn't.

I think the ECU can handle positive MAP as all it sees is a voltage range at the input PIN. Just remap the existing tables to suit the new MAP sensor.

The ideal solution would be to have a new MAP sensor that 'carried on' a bit above the old one. I could easily extend the tables in the ECU to give a bit more range.

Also there is another 'secret' in the UK 4A-GE ECU I haven't told you guys.

There is a hidden two wire interface to the ECU MCU which allows you to alter the ignition timing in 4 steps using an external switch.

Form memory I think it was 0deg, +2deg, -2deg, and -10deg. The stock ECU supports this function.

It would be easy to add a standalone knock sensor unit to this interface.
Obviously with my retuneable ECU the adjustment range could be enhanced...

[Denmark]

What do you charge for the Finshed ECU´s ?, You can PM me if you don´t what to tell about it yet!

I could send you a few MAP "Danisch AE86 ECU" to make a start with, if you had intrest.


I also don´t want the ECU to work off a knock sensor, I have mapped some Impreza´s with Link ECU ,and if this relais on the OE knocksenser the engine is going to blow sooner or later!.

I have in my car a Link Knocklink,and this is perfect in showing when there is knock(I always test it first, with a homemade set of earprotectes and some hose)


regards,
Skassa

[alimonos]

JMR_AW11 Wrote:

alimonos Wrote:JMR how can we start these hidden-secret(for race use?) programms in our ECU?

With a pair of wire cutters.

Seriously, on the UK ECUs these maps are locked out with a wire link which sets a logic level in the ECU.

These extra maps may only be present in the UK ECUs.
They are there on the UK MR2 and AE86 4A-GE ECUs.

I'll post the AE86 stock and secret maps on here when I get the chance and maybe someone can advise on what they are for.

It may just be for lower grade fuel (or for a different country?)

On some ECUs you may have to add a wire link rather than cut one.

Can you PM me the procedure to test them because with the wilder cam i 've got i can't pass MOT emissions test and/because i have problems with rich fueling at low rpms?

[phatBob]

JMR_AW11 Wrote:http://www.jmross.freeserve.co.uk/part3p2.html

The ignition timing for your 20V engine could be very different though.

You should really only play with your timing with the aid of a knock sensor monitor.

i.e. you should listen for signs of knock as you advance the timing to try for more power.

It would be a shame to damage that wonderful 20V engine with too much advance!

Thanks for that graph, that is way more advance than I am prepared to use at this stage of the game.

For ignition tuning I will be using the OEM knock sensor as VEMS has knock sensing built in. EGT is also useful as it allows you to measure the effect of ignition advance as you are able to detect the increase in temperatures before detonation sets in, VEMS can also read K-type thermocouples

[irishtwincam]

http://www.grid.co.jp/en/list/44.html

Could any of this software facilitate the writing of roms and changing of values rather than manual data entry?

So what if it may be outdated, kinda cool
JMR your work is fantastic, keep it up

[El_Camino]

That is fantastic thread! Is there any update by now?

[cannabolic]

great work JMR!!