SC400 ECU wiring for conversion

[dailey]

Hi guys,
Couple of questions about ecu wiring for a manual conversion. Its a 92 SC400 motor in a LH torana.

1. Is the Neutral start switch needed? Will the engine start ok with it removed?
2. Does the ecu need a gear signal (L or D) to drive properly.
3. Is STP required? Does it do anything for manual setup?
4. Any other tips?

cheers

Gloverman, Been checking out your youtubes. awesome stuff.
How much are your wiring instructions?

 

[gloverman]

How did you know id find your post? $150nz and im glad you called them instructions. Two different looms, with traction control and without. Theres a soarer loom hanging on the wall which will become the subject of a video at some point. Not for a while though.

 

[dailey]

Because you usually chip in for requests for help.
It is a UZZ31 w/ TRC.
I'm thinking of leaving the TRC throttle hardware on, making up a controller and using it as a power limiter / valet mode sort of thing.

 

[gloverman]

Fair enough.
I did a soarer years ago which the customer asked for an aftermarket ecu and to leave traction control working. I went through all the signals into and out of the ECU for TRC. I ended up making all work and found with two maps improved the traction on timing retard and fueling. In the end when he went to the track for a fun day if it rained it was faster with TRC on than off. I have proper instructions for wiring (I do sell them but it includes 30 mins of my time) and lots of free info and tips on my youtube channel. CartuneNZ.

 

[dailey]

sounds like an interesting project.
Was just thinking of having a pot connected to a stepper motor driver to close the sub-throttle.
I'll post a schematic when i get round to working it out.

 

[dailey]

Back on topic...
From checking the wiring diagrams, it looks like the ECU defaults to D when none of the other gear inputs are high.

 

[gloverman]

correct. You are showing good knowledge there. D is default. For years guys have said about "tricking" the ECU into a gear. All the Non vvti ecus default to D when wired correctly.

 

[dailey]

Thanks mate.
I setup industrial control systems (PLC's etc) for a living, so i do get this stuff.
Would just wonder if the ECU cuts the fuel or timing when it tells the gearbox to change gears.
I dont know if the ecu has that level of control.

 

[gloverman]

I did a job with a guy that did similar work recently, we did a wiring , aftermarket ECU and dash swap , we both learnt heaps and sorted his truck as well. I haven't run a scope on the outputs to see if the ECU has some advanced features like the later units. These old ones are pretty primitive.

 

[numbchux]

Thanks mate.
I setup industrial control systems (PLC's etc) for a living, so i do get this stuff.
Would just wonder if the ECU cuts the fuel or timing when it tells the gearbox to change gears.
I dont know if the ecu has that level of control.

It's certainly possible. I know on Subarus (where the engine and transmission have separate controllers), there is a wire specifically to tell the ECU to cut power a bit between shifts.

I see in the Lexus manual, there is a 4th solenoid (beyond the 2 shift solenoids, and torque converter), that is labeled "accumulator back pressure modulation". There's some documentation on this "4th solenoid mod", where you disconnect that solenoid to firm up shifts. https://www.clublexus.com/forums/pe...low-end-performance-try-this-it-s-free-2.html

 

[gloverman]

I was meaning more due to the age of the ecu. The early 1uz stuff is pretty basic compared to the later stuff. Idle control is primative, gear shifts not nearly as good as later ones etc. If i run a manual shift box on the auto i dont run S4. Its funny as lots of people call the cable to the auto the kick down cable, which its not, its the line pressure cable, S4 is there to reduce the pressure during shifts which im sure you understand. That one I've scoped and watched when I was playing with using an aftermarket ecu for the engine and stock ecu for trans.

Thinking about the timing/fuel change during shifts the ecu changed mapping when traction control operates. But its really poor again, sort of more of an massive drop them back on so makes for jerky results.