Funny adventures in electrical engineering

[Sparkie]

Sparkie, disco_cat, where are you all at on decoding the 1UZ ECU.. I have a 1999 SC400 that I would love to mod the ECU for better throttle response. Let me know where your at in the project.

Unfortunately without a PCM in hand I'm not much use, I've also got a small business on the go in addition to my regular job. Winter is a much more productive time for me in this dept.

For throttle response you could always try squeezing the FPR in a vice - Bump the fuel pressure for some transient enriching.

[disco_cat]

Sparkie, I can donate what I have by next winter

[Sparkie]

That'd be cool!

[disco_cat]

ok! I will probably do some tests before winter
I found out that engine control processor can be interchanged between "similar" ecus
I want to try trans control processor from tom's to determine what it does
After that I can send you the whole ECU. I can add some compatible processors that are supposed to "bolt on".
In addition to that, I can add one functional ECU of that type and immo bypass module programmed to both ecus
PM me for details. I think we may discuss what to send to you so you could make more use of it

[MarkT]

. How far did you get decoding it... or was it sparkie that was working on it also.

[disco_cat]

The results would be barely useful in practice anyway

[MarkT]

Unfortunately without a PCM in hand I'm not much use, I've also got a small business on the go in addition to my regular job. Winter is a much more productive time for me in this dept.

For throttle response you could always try squeezing the FPR in a vice - Bump the fuel pressure for some transient enriching.

I have a extra 1999 SC400 ECU that I could donate,, I was a h/w engineer many years ago, but I dont have access to any of the test
equipment any more.. This Denso unit has 3 CPU's is one traction control, then trans control, then engineer spark and fuel ??

[disco_cat]

traction control is a separate unit in any sc400

[Jeff Lange]

traction control is a separate unit in any sc400

It's actually only a separate unit up to 1997. 1998-2000 have drive-by-wire and the ECU controls the throttle control (including traction control). I would expect one CPU is for engine, one is for transmission and one is for throttle control.

Jeff

[MarkT]

It's actually only a separate unit up to 1997. 1998-2000 have drive-by-wire and the ECU controls the throttle control (including traction control). I would expect one CPU is for engine, one is for transmission and one is for throttle control.

Jeff

So who has enough back ground to decode one of the newer 1998 to 2000 drive by wire ECU's ?? Im willing to donate but the code extraction and decoding is a little over my head. A little better timing and quicker throttle response would make a big difference in one of these cars..

[disco_cat]

Jeff Lange
quick example 89540-50111 is abs/vsc/trc controller for '1999 toyota celsior / lexus ls400 , dbw, vvti and separate trc computer.
other cars, same story

the combined abs/vsc/trc computer commands engine computer to limit the power, which is not only achieved by throttle opening angle

[Sparkie]

So who has enough back ground to decode one of the newer 1998 to 2000 drive by wire ECU's ?? Im willing to donate but the code extraction and decoding is a little over my head. A little better timing and quicker throttle response would make a big difference in one of these cars..

I do, but I'm swamped with work. Nothing would happen until my industry settles down as it starts to get colder.

Also there may be limits to throttle response tuning - the throttle motor may simply not be powerful enough to crack the throttle faster, the throttle pedal may not update it's position at a high enough frequency or a bunch of other junk. I'd have to see what kind of control system has been implemented. It does sound exciting though! I've never hacked a car with an electronic throttle, I mostly avoid them myself.

as an afterthought it may also be possible to remove e-throttle related failure codes and slap a manual throttle on there - at the expense of traction control.

[MarkT]

I do, but I'm swamped with work. Nothing would happen until my industry settles down as it starts to get colder.

Also there may be limits to throttle response tuning - the throttle motor may simply not be powerful enough to crack the throttle faster, the throttle pedal may not update it's position at a high enough frequency or a bunch of other junk. I'd have to see what kind of control system has been implemented. It does sound exciting though! I've never hacked a car with an electronic throttle, I mostly avoid them myself.

as an afterthought it may also be possible to remove e-throttle related failure codes and slap a manual throttle on there - at the expense of traction control.

//
Sparkie, I think that is a good point about the throttle plate motor being slow. I was thinking this fall to try and come up with a way to put a one way clutch between the throttle cable and the throttle plate.. That is to let the cable pull the plate open for fast response but let the motor close it.. but then I dont really use the traction control anyway.. 90% of the time I have it set to off...

Is this something your interested in trying this fall ?? I can supply the computer.

Mark

[Sparkie]

Yeah, I'm very interested. Also your slip clutch idea sounds cool, it might not even throw a code if its a subtle enough assist.

[disco_cat]

MarkT
If you try looking at the throttle you will notice it acts instantly. Also, the japs have already made a kit that lets you kill the transmission by not allowing ECU to close the throttle if you open it by more than 30% (but idle speed control is still performed by ecu). But the kit is useless for stock engines running stock management system.

[MarkT]

MarkT
If you try looking at the throttle you will notice it acts instantly. Also, the japs have already made a kit that lets you kill the transmission by not allowing ECU to close the throttle if you open it by more than 30% (but idle speed control is still performed by ecu). But the kit is useless for stock engines running stock management system.

You kind of lost me on that one.. What jap company has a kit to kill the transmisson ?? As Im running a mostly stock lexus SC400 and stock ECU,, If there as a different option for a ECU or a updated ECU, I would not have to go down this path of re-mapping a OEM ECU.
Sorry, Im just not following you.

I have looked for years for ECU options for the SC400 and have found none.. I see from a earlier post you had some type of moded
Denso ECU with a added PCB and the bottom right CPU removed..

What did this do and were did you get it from ????

thanks

[Sparkie]

I have looked for years for ECU options for the SC400 and have found none.. I see from a earlier post you had some type of moded
Denso ECU with a added PCB and the bottom right CPU removed..

What did this do and were did you get it from ????

I designed and built the PCB, and programmed the CPLD that enables the external operation - it's the same sort of system as a TOMS ecu for a MKIII supra, just a few more quirks related to the microcontroller. This allowed me to run my own code on the computer, so I took the old code and begun the painstaking process of disassembling and reverse engineering it to figure out what everything does. I'm not done this process yet, but I have found the timing tables and algorithms, the fueling algorithms and the rev limiter. On my personal ecu I've bumped fuel cut redline to 7500 RPM and removed the detonation sensor timing subtractions (I had a good reason for this, really).

As a side benefit to the modded ECU I've added a USB connector to communicate with the micro, and I've written a code/map loader and a data logger so I can get more disassembly done.

[MarkT]

I designed and built the PCB, and programmed the CPLD that enables the external operation - it's the same sort of system as a TOMS ecu for a MKIII supra, just a few more quirks related to the microcontroller. This allowed me to run my own code on the computer, so I took the old code and begun the painstaking process of disassembling and reverse engineering it to figure out what everything does. I'm not done this process yet, but I have found the timing tables and algorithms, the fueling algorithms and the rev limiter. On my personal ecu I've bumped fuel cut redline to 7500 RPM and removed the detonation sensor timing subtractions (I had a good reason for this, really).

As a side benefit to the modded ECU I've added a USB connector to communicate with the micro, and I've written a code/map loader and a data logger so I can get more disassembly done.

WOW,, I want one,,, So the ECU you were using is from a MKIII ?? From the pic I saw, it has the same markings as my 1999 SC400 VVT Denso ECU...
If this is true, then what your doing could be used on a SC400... WOW I like it..

[disco_cat]

MarkT
https://www.youtube.com/watch?v=vUFxl9f9X88
that's regarding the jap kit
Regarding stock 1uzfe vvti
My car is 1570kg complete with driver, makes 0-100kph in low 6's , I can't depress the pedal so quick that I would need to modify stock ETCS system
My Tom's ECU was sourced for cheap from Japan by pure occasion
It didn't improve anything that can be firmly measured
By feel, it improved bottom end torque and slightly improved fuel mileage
For me , its main features were speed limit cut and hydro fan operation.

[Sparkie]

So the ECU you were using is from a MKIII ?? From the pic I saw, it has the same markings as my 1999 SC400 VVT Denso ECU...

No, I wasn't clear. The ecu is a 94 (maybe?) SC400 part. I have modified it in a manner similar to tuned MKIII supra ecus, but with parts I built myself.

So definitely what I've done can be done to an SC400, my car thinks it's a SC400 anyways. The LS400 PCM is basically the same and would accept the same modification.

Now I haven't looked at a '99, and it may be drastically different, but I'm always up for some hacking.