Problem - Auto Aristo ECU running Man. 1JZ

[JPsToyota]

I wonder if anyone else on here is running a manual 1JZ with an automatic Aristo ECU?

I bought an 88' MKIII with this setup (and inherited all of the past owners problems and shortcuts of course hah) and have a problem that I just can't seem to solve or find any information on. The engine runs really well on this ECU, it's very smooth and runs well down low.

BUT For some reason if I go over about 80% throttle above about 5500 RPM, the ECU kicks on a rev-limiter and I will have to go below 80% throttle to continue through the rev-range. If I keep it below about 80% throttle it will rev out fine all the way to the 6700-6800 rev limit.
I can go 100% throttle no problem until 5500 RPM or above.


Anyone have any ideas? As you can imagine this puts a little stranglehold on the fun of the car. I'd like to get this sorted out at least until I decide on and can afford a new ECU solution for some bigger power.

I'm kicking around a couple of ideas in my head involving maybe a neutral rev-limit on the ECU or some sort of TPS problem right now, trying to research. I don't think either of those is really the issue though.

 

[GotTurbos?]

So you're hitting an actual rev limiter? It sounds like you could be hitting boost cut, but you'd be able to continue after it cuts briefly.

 

[tissimo]

any codes?

 

[JPsToyota]

So you're hitting an actual rev limiter? It sounds like you could be hitting boost cut, but you'd be able to continue after it cuts briefly.

Yes, it's an actual rev-limiter. I should've mentioned that I already tested for boost cut, as that is what I originally thought it was, sorry. I hooked up a Zener diode and limited the voltage output of the MAP sensor to 3.85 volts and it still had this same rev-limit problem.

 

[JPsToyota]

any codes?

It's not giving me a CEL, but for all I know about this car, the CEL light doesn't even work.

Tissimo, I believe I have heard through a couple of people that this is your "friends" old car that you helped swap. I am not blaming the problem on you obviously, just thought it would help you be a little more familiar with the car. From what I understand, the problems all came about after the previous owner swapped the 1JZ ECU out for this Aristo ECU himself.
I'm just tracking down and fixing problems as I find them.

I should check the CEL.

 

[Satan]

Check the CEL and go from there. I know a few ppl running the Aristo ECU on 1Js without issues, but the configuration varies (single, stock twins, etc).

 

[tissimo]

Yea its his old car. We didn't get a chance to look into it before he sold it.

The CEL might not be on, but there maybe a code. He had a couple codes from before, and cleared the ecu, but never checked to see if there were any afterwards.

 

[JPsToyota]

CEL is working fine, but isn't on when the rev-limit problem happens.

It does come on when I hit the speed limiter and boost cut.

I'll have to figure out how to check codes on this car and see if it is storing any, hopefully Toyota has a pedal dance or something like my Nissans haha

 

[Guyana00]

Any more info on this configuration? I'm the process of a search right now and may be doing a JZ swap this summer but have no ECU yet.

 

[JPsToyota]

I think I have discussed this problem in other people's threads, but I wanted to update this thread.

I ended up fixing the problem after some research on Aristo boards, the automatic Aristo ECU has a neutral rev-limit built into it that prevents the user from going over a certain RPM without being in gear. When you hook it up to a manual car, the ECU is usually tricked to see that it is in neutral or park to allow the car to start correctly. (Auto car wont start in drive).

Well we can see the problems forming already, cant we? Trick the ECU into thinking you are in Neutral, neutral rev-limit is always activated.

I don't have specifics right now on this computer, but I ended up going through pin-outs of the ECU (Aristo pinout can be found but is like striking gold, 2JZ-GTE JDM Auto Supra ECU is very similar) and disconnecting wires that had to do with the neutral safety/start switch until I lucked out and it worked.
Removing the wire had no ill effects on my car and took the neutral rev-limit away. I cant remember what pin it was, but I'd start around the 70's IIRC, maybe 76 because the Supra pinout I'm looking at now has a neutral start pin at 76. I DID NOT USE THE JDM SUPRA PINOUT I AM LOOKING AT NOW for my own work, so this may be wrong, it is just a guess and a good place to start.

Now, there is a possibility that your car may not start after removing this wire. I expected mine not to start, but my car is a hodge-podge of different wiring, harnesses, and connectors and I may have just been lucky. You will have to find your own way around this if it will not start, maybe wiring it to a switch or to the clutch switch, be creative.

The car now sceams to about 6800 RPM, neutral rev-limit free, and runs great on this ECU. Now if only I could find a way to raise the low rev-limit, I'd be golden...

- JP

 

[Zazzn]

so that means you need to set up a momentary switch to activate it... Like the stock NU start switch on the 5spds... Hook it up to that press the clutch and volla.