Interest in Tuning for Boost with the Stock ECU

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24 November 2006
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130
I haven't posted here in years! Recently, I have made major leaps and bounds with decoding the Legend's ECU. To sum it up, I've got a full commented dis-assembly with the master program stack and "engine running" stack identified and quite a few of the many programs identified. I started by reverse engineering the A/D, check engine light and limp mode routines. From there I was able to find the variables for the high and low limits of all of the sensors, the substitute values for when a sensor fails and most importantly, the location of all of the major sensor values in RAM. I was able to write a primitive program that hijacks the serial port and logs those values one at a time in raw hex. I've also identified just about all of the program switches and have the ability to turn off various sensors and their associated CEL's - Knock, EGR, Oxygen (OPEN LOOP!), Fuel Injector and Barometric Pressure sensors.

Hardware & software wise, I'm running a Moates Ostrich emulator with a trace feature. I use this in conjunction with TunerPro RT program by Mark Mansur and a custom definition file I've brewed. This allows real time tuning and modification and pseudo datalogging with the trace feature activated. I've got hand drawn schematics of the A/D converters, and hybrid ROM setup, datasheets (and programming manual for the MCU) for most of the ICs on the board and a good idea of what they do. I also have a kick ass custom made engine simulator set up on my bench for more invasive testing. This is my favorite hobby and I probably wont stop until I know what every byte in the RAM and ROM does in this ECU :).

What I've learned with the Legend's ECU directly ports to the 90-93 NSX's ECU, as they are set up almost identically. The ignition, fuel and other maps as well as the variables and most importantly, the sensor values, are in the same locations in ROM & RAM. These engine computers could be considered sisters (I need more information about the drive by wire ECUs). For instance, there are a handful of Legend owners that use the NSX specific EMS as a plug and play system - I think 3 wires have to be swapped around in order to make it work.

These Panasonic made ECUs were way ahead of their time and I admire everything about them. From the near military grade construction to the elaborate hybrid memory setup to the lengths that were taken for proper ground shielding. Even the assembly language used to code is eloquent. There are 6 individual coil pack and fuel injector drivers, individual banked feedback oxygen and knock sensors, and provisions for communicating with the traction control and auto transmission for torque reduction. Many features aftermarket computers lack. They used a top of the line Hitachi h8 16bit RISC processor and in the early 90's this single chip alone cost upwards of $500.00. The descendants of these processors are still used today.

My primary goal with this ecu is to have some or all of the features of an aftermarket engine management system with no piggyback controls or external modifications. I'd like to follow in the footsteps of the grassroots movement a few years ago to reverse engineer the OBD1 civic & integra ECUs (www.pgmfi.org). They have proven without a doubt that the stock engine computer can be tuned for any setup. Although those ECUs use a completely different processor and manufacturer, the same general idea applies.

The main items on the agenda are:
1. Tune in high resolution for boost.
2. Complete realtime datalogging with integration into tunerpro.
3. Retained function of the traction control and automatic transmission.
4. Use a modified PWM output as a boost controller.
5. To have it pass emissions.
6. Add sensors such as EGT and wideband o2 to be datalogged.

My current problem is time. I started this project years ago when I had a lot more of it. I now own & operate a full service Acura Legend specialty shop in Bristol, CT. Now that the shop has picked up I don't have as much time as I used to. It's the worst catch 22. Lately it seems this is universal to life in general - when I had the time I didn't have the knowledge and now that I have the knowledge I don't have the time. I have been staying up sometimes until 4 in the morning playing with this ECU which hasn't made me too popular with my girlfriend. I've determined that I'm addicted to it!

I have thousand of hours invested into this project, I've taught myself how to read assembly and learned quite a bit about embedded systems in the process. I need some help from the members on this forum. One of the major cornerstones to a successful reverse engineering project is the ability to compare and contrast. I need dumps of the stock 27C256 chip from year to year, and most importantly from region to region - European and Japanese at the least. I need a working stock NSX ECU that I can hook up to my engine simulator to do tests on. I also need a broken NSX ECU that I could render even more useless to do an MCU dump on. I would like to examine the ECUs used on the drive by wire setup on the (94+?) NSX's - it would be nice at the very least to see a high resolution photo of the inside of it. I need to know if there are any old school ASM programmers on here that might be willing to help with some of the coding. Basically I'd like to start a network with you guys and go from there.

Please let me know if you are interested and what you can do to help.

Cheers!

-Matt
 
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:eek:. Hobby or not. This should get some type of Nobel prize or at least a stickie at the top of this page.

Bravo and good luck!!!! Can you make it like a Hondata?

Thanks
 
:eek:. Hobby or not. This should get some type of Nobel prize or at least a stickie at the top of this page.

Bravo and good luck!!!! Can you make it like a Hondata?

Thanks

I don't know about all that, it's not rocket science. LOL! Thank you though. The point of all this work is to make it similar to what Hondata does.


If you sent as an email, I didn't get it, I changed my email years ago and never updated it on this forum. I'm updating it now.

Thanks!

-Matt
 
Simply amazing.

I have a 95 OBD2 DBW ECU that was damaged by improperly connecting the 02 sensor connectors and am putting in an aftermarket EMS.

Theoretically, I have no use for my ECU, which does work but constantly throws a CEL.


- Craig
 
Simply amazing.

I have a 95 OBD2 DBW ECU that was damaged by improperly connecting the 02 sensor connectors and am putting in an aftermarket EMS.

Theoretically, I have no use for my ECU, which does work but constantly throws a CEL.


- Craig

Hi Craig would you mind posting up a high res picture of the circuit board? What I'm looking for is whether or not there is a ROM chip on the board or if the coding is 100% internal to the processor. Once you post the picture I may ask you to provide a part number off a chip if necessary.

Most Honda obd2 computers use internal programming and surface mount technology. I think it was a federal mandate to prevent "tampering" with the emissions system. On the other hand, though, the NSX & Legend have proven to be on the "different" side. Also, depending on what type of construction it uses, I may be able to repair it for you.

-Matt
 
Ummmm.......what!? You mean I didn't need an AEM EMS? That would have been nice to know! :eek:

Not quite, it's still very much untested and there is quite a bit more that needs to be figured out. Everything seems to work on paper though.

-Matt
 
Hi Craig would you mind posting up a high res picture of the circuit board? What I'm looking for is whether or not there is a ROM chip on the board or if the coding is 100% internal to the processor. Once you post the picture I may ask you to provide a part number off a chip if necessary.

Most Honda obd2 computers use internal programming and surface mount technology. I think it was a federal mandate to prevent "tampering" with the emissions system. On the other hand, though, the NSX & Legend have proven to be on the "different" side. Also, depending on what type of construction it uses, I may be able to repair it for you.

-Matt


Will do. I'll pull it out of the car tomorrow and get a pic of the internal gubbins for ya.

You know you're a sick, sick man that really has toooooo much time on his hands :tongue:
 
You need to talk to C-Speed. He's already figured out much of this a few years back.
 
You need to talk to C-Speed. He's already figured out much of this a few years back.

Small world...

I was following his posts at PGMFI.org and AFAIK he didn't get that far at all. Check in the C-Series section under "All PY3/PR7 I have found". He was using the very crude definition file for tunerpro by Peluca and the Beavedit program. I attempted to reach out to him more than a few times unsuccessfully, and at one point he reached out to me but I wasn't active on PGMFI at the time.

I've come leaps and bounds since then! With what I've discovered with the disassembled MCU and ROM program, the engine simulator and my crude data logging I now understand why what he was trying to do wasn't working.

EDIT: He posted that he's running an AEM EMS here: http://www.nsxprime.com/forums/showpost.php?p=1086515&postcount=1

-Matt
 
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Actually I think he gave up because the FIC came out. He sold his NSX too.
 
Actually I think he gave up because the FIC came out. He sold his NSX too.

Correct me if I'm wrong, but you really can't use the FIC to its full potential with a OBD1 ECU *UNLESS* you can see the current and long term fuel trims. Have there been any 91-94 NSX owners that have tuned succesfully with the FIC?

-Matt
 
Correct me if I'm wrong, but you really can't use the FIC to its full potential with a OBD1 ECU *UNLESS* you can see the current and long term fuel trims. Have there been any 91-94 NSX owners that have tuned succesfully with the FIC?

-Matt
There are a few obd1 nsx turbos running with the fic. I was just in brians car last weekend and he is obd1 and fic. Seemed to work great.
 
Very interested in a plug and play solution. My life is too busy for constant tuning sessions.:cool:
 
How hard would it be to create a program that would access the serial port of the OEM ECU and log the fuel trim data, commanded ignition, and knock from the OBD1 ECU's. If so then at least in the short term the FIC would be much easier to setup. Might not be the holy grail everyone is looking for but would make for a low cost solution to a full ECU.

Dave
 
How hard would it be to create a program that would access the serial port of the OEM ECU and log the fuel trim data, commanded ignition, and knock from the OBD1 ECU's. If so then at least in the short term the FIC would be much easier to setup. Might not be the holy grail everyone is looking for but would make for a low cost solution to a full ECU.

Dave

Dave, Check these videos out. I'm still working on knock and fuel trim but I have current ignition and modified ignition timing (actual timing). I have most of the ignition modifiers, such as A/T shift timing reduction, Ignition Timing Adjuster, Coolant Temp, etc - I just need to start digging a bit more and get the variables documented. I also found the current fuel injector pulse width from the map but I haven't found the final desired (modified) pulse width.

What I need to do is get my RAM/ROM dump program working so that I can dump the contents of the RAM into a file for comparison. If I can take multiple RAM dumps - with the engine cold/hot, under high load and under low load, deliberately inducing knock or lean/rich mixture, etc - and compare those dumps to each other, these values would stick out like a sore thumb.

I need an OBD1 NSX ECU to play with on the bench can you guys help or what?!?!?


This video demonstrates the first datalogging ever with the Legend/NSX ECU. I apologize for the extended length and the unedited nature of the videos, they were done on the fly.
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This video shows the raw value from the ignition map (unmodified) and how the table interpolation routine works. I made this video as a demonstration for a gentleman on the Legend forums.
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-Matt
 
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im putting an aem box in mine shortly, and i dont live very far from you. would you be destroying the ECU in the process of getting the dumps though?
 
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