4age ECU operation - Toyota Nation Forum : Toyota Car and Truck Forums

rezzle · 03-17-2003, 12:52 PM

Does anyone know exactly what inputs the 1989 4age ECU uses to correct ignition timing and under what conditions?

neil85AE86 · 03-18-2003, 10:53 AM

Try, yoshio at Japanese Automotive, I think he charges around $1000 CDN for a reprogram

I do know that timing is affected by engine load, which is generated from a combination of rpm signal, TPS signal (3 wires) and AFM signal (4 wires). The AFM is critical for timing, it is not a simple RPM curve.

Good luck.

Neil

rezzle · 03-18-2003, 11:34 AM

Thanks Neil I was more worried about the O2 sensor. Last bit I read about Toyota ECU's stated the O2 sensor affected the timing at idle.

My problem is that propane runs best at 15.5 % O2 stoichiometric and gasoline runs at 14.7% There is a slight timing change between the two fuels but it seems to be pretty consistant throughout the whole RPM range.

neil85AE86 · 03-18-2003, 12:05 PM

interesting.

The octane is much higher with propane.. theirfore you can get away with a bit more advance... or is it the other way around?

Are you running the stock 4age ECU or the 4agze ECU?

Did you consider installing an inline resistor so that the ECU is fooled into thinking that it is running a little rich all the time?

Neil

rezzle · 03-18-2003, 05:24 PM

Pretty much stock 4age, If you have seen any of my other posts you will know the reason I am switching is because I already broke the thing once. " I have a $90.00 paperweight in the form of a piston sitting on my desk. "

If I happen to come across some real money I will consider investing in some lower compression forged pistons but I have done considerable research and I don't think the drivetrain will be able to handle much more HP than I am going to be making anyway. I have conservatively estimated 160HP or so. I really don't want much more for fear of increased unreliability and this should be enough for me to be quicker than most cars I come acrosss if not at least turn a few heads.

As for the timing issue this is one of my sources ...
http://franzh.home.texas.net/engine.html#One
"Engines over 9.8 to 1 (and no more than 11.0 to 1) should have the initial timing set at 4° with a total timing of 32° btdc by 2600 rpm."

If you don't think forced induction propane engines produce power - check out this page. ...
http://www.truckworld.com/4x4-OffRoa...rboWillys.html

As for the sensor I have thought of adding a voltage divider but if the O2 sensor doesn't screw with my timing and if I don't get a check engine light, it can do whatever it wants and I don't care. The fuel is going to be supplied by the converter and not by the fuel injectors. I will probably buy a meter witch can measure the voltage and install it or recalibrate the thing so that I can read the actual O2% from the stock signal. One thing at a time though

I will dyno my car and see how close I can get the timing to what I want with the stock system. If I run into troubles, and to be honest I think I will, propane likes a stronger spark. I will have to switch over to a crank fired ignition system. I just wanted to make sure I could start up and drive the thing without catastrophic failure. There is a page or two on MrMR2.com that refers to changing a 4age over to propane and they did very little. I am skeptical however after my first experience with modding this car and don't wanna screw myself again.

neil85AE86 · 03-18-2003, 07:55 PM

sounds like an interesting project.

You may want to checkup on MegaJolt every now and again. I'm currently building a MegaSquirt/MegaJolt turbo 4ag. The MJL is not quite ready yet, hopefully soon.

One guy already has a turbo 4ag running with the Ford distributorless EDIS ignition, I'm shooting for ........sometime this year. I just need time, I'm done collecting parts!

I may be running the MS shortly, it's built, and functional just not 100% convinced I want to run it piggyback with the OE ecu for timing at the moment, I have a few ideas....

http://www.bgsoflex.com/megasquirt.html
http://www.bgsoflex.com/mjl/mjl_edis.html

Good luck.

Neil

neil85AE86 · 03-24-2003, 02:54 PM

Hey, I just got a note from a fellow Megasquirter, and he removed the AFM from his '85 Supra and the car works great without it, so maybe it doesn't contribute feedback for the timing control afterall. He's using the OE ECU for timing.

Neil

rezzle · 03-24-2003, 07:08 PM

I find responding a good way to 'think' outloud so excuse me if I wander on this post.

Did he completly remove the thing? or is it still connected but not in the airstream.

I was able to get a hold of a mixer for free this week so one part of my financial puzzle is solved heh they cost about 300 cdn new. I will be ducting it to the supercharger and connecting the waterlines this weekend.

I think the AFM does have something to so with the timing advance.. I was also under the impression the AFM was necessary for calculating engine load and ignition advance.

read this sticky from the auto-x thread
http://www.toyotanation.com/showthre...threadid=13306
there is a whole pile of info there on Toyota electrical .. just nothing 'specific' to year type and model.

Unless the Timing is regulated by the RPM and throttle positioner only once I get the thing running the first thing I am gong do to is a very thorough timing check
Rezzle.

neil85AE86 · 03-24-2003, 07:40 PM

He has completely removed his AFM, and only has the idle control switch from the TPS connected (4 wire TPS just like the 4age).

Maybe we are all thinking into this a little too much. For the average person using the car as a street car, most manufacturers do tune a little rich and probably a little extra retard for engine longevity, so possibly the curve is strictly in relation to RPM. The simpler the system, the less to go wrong maybe, I dunno, just a thought.

Since he is using MAP based standalone fuel control, all his load is calculated from manifold pressure. Fuel enrichment from TPS position etc.

This is in a highly modified car with a turbo added. He is using an aftermarket spark amplifier, with boost timing retard... so possibly if the timing is being affected, his spark amplifier is lessening the effects.

I'm going to be doing a similar test of my own shortly. The way I am setting up my Megasquirt I will easily be able to switch between the MS and the OE ECU. I'll try both and post my feedback... might not be for a month though, still have to put the rest of the car back together.

Neil

rezzle · 03-25-2003, 12:19 AM

Quote:

Originally posted by neil85AE86
might not be for a month though, still have to put the rest of the car back together.

Neil

I know the feeling. Its been almost two years for me and driving my wife's automatic transmission Echo is starting to get a little 'old' heh.

Rezzle. (Brent)

rezzle · 06-16-2003, 11:36 PM

Bump

I am still curious if anyone knows the exact operation of the ECU (what types of inputs do what)

Thankyou.

Hemi3TC · 06-17-2003, 07:32 AM

Go back to school at www.autoshop101.com
Lots of Toy stuff and tests.

Hemi3TC

Quote:

Originally posted by rezzle
Bump

I am still curious if anyone knows the exact operation of the ECU (what types of inputs do what)

Thankyou.

neil85AE86 · 06-17-2003, 11:08 AM

fyi, if you'd have read the thread and followed the links you would have found that autoshop was already mentioned

Go back to school and learn to read

neil

rezzle · 06-17-2003, 01:37 PM

Thanks Neil, this week I have given up on folks like that and refuse to be baited.

Anyways back on topic.

I'm thinking I am probably worrying about nothing.

If Bill can do it I can do it.

Taken from

http://www.billzilla.org/4agmods2.htm

"The cheap & nasty way to make the dizzy work without the factory computer is to simply hook up an ignitor module (eg, Bosch) and then run the engine without any spark advance. Speaking from about 70,000km experience of this, it's really not big deal - The only hassle is that the engine can be a little hard to start when cold or very hot. ....

.... Yet another way to control the spark, even on a heavily modified engine, is to use the factory computer in parallel with whatever you have controlling the fuel already. All you have to do is run the tacho trigger and power to the factory computer and run the right output wires from it to the factory dizzy and it should control the spark in much the same fashion as a stock engine does. (not sure if the factory computer uses MAP sense to modify the spark advance output or not, but it'll still work ok, and certainly be better than nothing in any case) "

Rezzle (Brent)

Hemi3TC · 06-17-2003, 04:59 PM

Well I guess I missed it, Is that a crime? What message already mentioned autoshop101.com?

What is exactly wrong with going to autoshop101 to learn about
ECUs? Autoshop 101 gives the information on OBDI ECU inputs from Toyota.

Hemi3TC

Quote:

Originally posted by neil85AE86
fyi, if you'd have read the thread and followed the links you would have found that autoshop was already mentioned

Go back to school and learn to read

neil