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Discussion Starter · #1 ·
71dsp..

Since you know the most about the 97-UP Prelude! I need your help

Question: The Eprom in the 97-Prelude ECU, Particularly 1997 is the Eprom 84pin?

please help...
thanks..
vnt

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1997 Prelude (Non-Sh) Eucalyptus Green "TEAM ALL SPORT RACING"
AEM Intake, 5Zigen Fireball Exhaust w/Gutted Cat, 18 Degree Advanced Timing, DC C/C Header, DC Short-Shifter, Gutted Interior, Sprint Race Springs, Front & Rear Strut Bars. Clear Lenses All Around w/Hiper White Bulbs & Alteeza Tailights.
[email protected]
"BIG BLUE FLAME"

[This message has been edited by vntperformance (edited April 05, 2001).]
 

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Heh-heh... he thinks you know the most...

The '96 and up (OBD2) VTEC Prelude ECU, including all of the 5th gens, has no EPROM in it. It also has no EEPROM. It also has no RAM. In fact, ALL it has is an OKI microcontroller that has, built into the chip, 64K of ROM and 64K of RAM. There is no UV- or electrically-reprogrammable memory space.

What this means is that we don't have an "EPROM." You cannot buy a "chip." Any modification of our ECUs would require desoldering of the 128 pin QFP (surface mount) microcontroller and replacement with a reprogrammed version. Not only is this expensive, it's a delicate and time consuming process that requires specialized desoldering equipment and programming equipment different from what ECU programmers use now.

To the best of my knowledge, no one can reprogram an OBD2 ECU yet for a Honda.
 

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Discussion Starter · #3 ·
So what your telling me is the Largest Chip in the ecu of the 97 Prelude has 128pins, correct?

vnt


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1997 Prelude (Non-Sh) Eucalyptus Green "TEAM ALL SPORT RACING"
AEM Intake, 5Zigen Fireball Exhaust w/Gutted Cat, 18 Degree Advanced Timing, DC C/C Header, DC Short-Shifter, Gutted Interior, Sprint Race Springs, Front & Rear Strut Bars. Clear Lenses All Around w/Hiper White Bulbs & Alteeza Tailights.
[email protected]
"BIG BLUE FLAME"
 
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Originally posted by vntperformance:
So what your telling me is the Largest Chip in the ecu of the 97 Prelude has 128pins, correct?

vnt
I have no idea. I haven't cracked open a 5Gen ECU, but marcucci has mine right now, and I am sure he has opened it up and messed around with it a bit.

What are you planning to do? No one I know of, so far, can reprogram 5Gen ECUs.

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Billy
North Texas Prelude Owners Group
www.ntpog.org
 

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Discussion Starter · #5 ·
71DSP

What I'm trying to do is, if I can find out the biggest chip in the ECU has 84 Pins or less, then I'll be able to reprogram the ECU w/o a Problem.

vnt


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1997 Prelude (Non-Sh) Eucalyptus Green "TEAM ALL SPORT RACING"
AEM Intake, 5Zigen Fireball Exhaust w/Gutted Cat, 18 Degree Advanced Timing, DC C/C Header, DC Short-Shifter, Gutted Interior, Sprint Race Springs, Front & Rear Strut Bars. Clear Lenses All Around w/Hiper White Bulbs & Alteeza Tailights.
[email protected]
"BIG BLUE FLAME"
 
G

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Originally posted by vntperformance:
71DSP

What I'm trying to do is, if I can find out the biggest chip in the ECU has 84 Pins or less, then I'll be able to reprogram the ECU w/o a Problem.

vnt
How? Do you know how the code works? Have you been able to extract the code? I don't think it's like reprogramming the 4Gen ECU. I believe they use different processors.


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Billy
North Texas Prelude Owners Group
www.ntpog.org
 

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Discussion Starter · #7 ·
71dsp..

I did some research, and think that I can break it...and redo the redline..and all mapping..and remove the speed limiter..

Now were in business..


vnt



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1997 Prelude (Non-Sh) Eucalyptus Green "TEAM ALL SPORT RACING"
AEM Intake, 5Zigen Fireball Exhaust w/Gutted Cat, 18 Degree Advanced Timing, DC C/C Header, DC Short-Shifter, Gutted Interior, Sprint Race Springs, Front & Rear Strut Bars. Clear Lenses All Around w/Hiper White Bulbs & Alteeza Tailights.
[email protected]
"BIG BLUE FLAME"
 
G

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Originally posted by vntperformance:
71dsp..
I did some research, and think that I can break it...and redo the redline..and all mapping..and remove the speed limiter..
Now were in business..
By all means, try it. Let us know if you are successful. What kind of chip are you planning to use after you remove the OKI chip from the ECU board?

I am curious about something. Did you advance the timing as much as you could? This didn't give you any MILs or anything? Also, do you know if you are beating the hell out of the rod bearings or not? After doing some research, I have found that advancing the timing too makes peak cylinder pressures very high, which pushes down much, much harder on the piston and rod assembly. Reason why you don't see a big increase in power is that the crank is close to TDC, so the mechanical lever is quite short. This really beats up the rod bearings, rods, and pistons. I am just curious as to what affect this has on rod bearing reliability.

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Billy
North Texas Prelude Owners Group
www.ntpog.org
 

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Originally posted by marcucci:
Heh-heh... he thinks you know the most...

The '96 and up (OBD2) VTEC Prelude ECU, including all of the 5th gens, has no EPROM in it. It also has no EEPROM. It also has no RAM. In fact, ALL it has is an OKI microcontroller that has, built into the chip, 64K of ROM and 64K of RAM. There is no UV- or electrically-reprogrammable memory space.

What this means is that we don't have an "EPROM." You cannot buy a "chip." Any modification of our ECUs would require desoldering of the 128 pin QFP (surface mount) microcontroller and replacement with a reprogrammed version. Not only is this expensive, it's a delicate and time consuming process that requires specialized desoldering equipment and programming equipment different from what ECU programmers use now.

To the best of my knowledge, no one can reprogram an OBD2 ECU yet for a Honda.
Hey, do you know the part number for the OKI part?
 

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Discussion Starter · #10 ·
71dsp...

I'm gonna be using a Techtom Chip...I let you know how everything turns out!

I haven't check on the wear of the r/bearings yet, but will when I tear down the bottom end to utilize the Type-S Pistons & Rings..

I'll let you know how it turns..you never know I might be the first one with an ECU upgrade to the 5g Prelude.

thanks..
vnt

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1997 Prelude (Non-Sh) Eucalyptus Green "TEAM ALL SPORT RACING"
AEM Intake, 5Zigen Fireball Exhaust w/Gutted Cat, 18 Degree Advanced Timing, DC C/C Header, DC Short-Shifter, Gutted Interior, Sprint Race Springs, Front & Rear Strut Bars. Clear Lenses All Around w/Hiper White Bulbs & Alteeza Tailights.
[email protected]
"BIG BLUE FLAME"
 

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Sooo many questions...

- The largest chip in the ECU is the OKI microcontroller, used as the main "processor" in the ECU. This holds the code in masked ROM (put in at OKI's fab when the chip was made) and the RAM used for program space and variable storage.

- The Oki part is a MSM66509. I believe it is no longer available, at least not through "common" channels.

I am not sure if this chip was ever available in the states. It's now on their "discontinued products" list which tells me it's out of production and likely no longer available. Honda probably made a lifetime buy on this part.

I have no idea what Honda is using past '99 (I've only had a '97 and '98 open), it might very well be different. It wouldn't be terribly difficult for Honda to port the code over to another chip in OKI's line that uses the same core or instructions.

I'm not sure how to state this more clearly, but this chip CANNOT be reprogrammed. Not only would you need a programmer with a QFP head (EXPENSIVE!), you'd need to get a new chip. The ROM is ROM, not EPROM, not EEPROM, and cannot be reprogrammed. You'd need to get a new chip (the MSM66P509, no less, the programmable one) and burn that. This assumes you can read the old one and get the data out and modify it, first.

Something that any programmers out there should know is that there is a second processor on board - an 8 bit MSM65512. I haven't figured out what he does, yet, I was going to but stopped research when I found what reprogramming the box would take.

What I've heard, from Japanese Auto, is that Techtom hasn't cracked our box yet. Any operation would require removal of the stock chip and replacement with a programmable version. That operation alone would take at least an hour, maybe more, much more time than it would for a 4th gen ECU. I highly doubt the OKI chip is still available, and unless Techtom has their own fab, I doubt they will make one pip-for-pin compatible. Anything else (any other processor) would require some serious customization (like a daughter card) and honestly wouldn't be worth the development cost.

My analysis is: convert to OBD1. Otherwise, get an aftermarket ECU altogether.
 

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Discussion Starter · #12 ·
marcucci:

Man, you know your stuff...i gotta give to you! I'm a Computer Systems Engineer, and If my boy says he can do it, then I'm gonna at least give it a try.

thanks for the info..

vnt

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1997 Prelude (Non-Sh) Eucalyptus Green "TEAM ALL SPORT RACING"
AEM Intake, 5Zigen Fireball Exhaust w/Gutted Cat, 18 Degree Advanced Timing, DC C/C Header, DC Short-Shifter, Gutted Interior, Sprint Race Springs, Front & Rear Strut Bars. Clear Lenses All Around w/Hiper White Bulbs & Alteeza Tailights.
[email protected]
"BIG BLUE FLAME"
 

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haha, you know your stuff Maybe that's why Honda's discontinuing the Prelude, they ran out of ECU's!

I did some surfing, and the 66P509 is OTP! Wow, that really sucks! And worse! OKI doesn't list a replacement/substitute/updated part. I did find some emulators though. Runs on Win95
 

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Originally posted by vntperformance:
marcucci:

Man, you know your stuff...i gotta give to you! I'm a Computer Systems Engineer, and If my boy says he can do it, then I'm gonna at least give it a try.

thanks for the info..

vnt :D

The P is OTP, and it's all that's out there. Ours is the factory-masked part that is basically trash.

I'd like to talk to whoever thinks they can reprogram this part, or this ECU. I really don't think it's worth the effort with availability of the chip, or having to fab a new part for the old "hole." A new ECU altogether would be easier and more productive.

Oh, and thanks... Billy's not the only one who knows something : )
 
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Originally posted by marcucci:
The P is OTP, and it's all that's out there. Ours is the factory-masked part that is basically trash.

I'd like to talk to whoever thinks they can reprogram this part, or this ECU. I really don't think it's worth the effort with availability of the chip, or having to fab a new part for the old "hole." A new ECU altogether would be easier and more productive.

Oh, and thanks... Billy's not the only one who knows something : )
Yes, you know much more than I do on the electrical side of things!

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Billy
North Texas Prelude Owners Group
www.ntpog.org
 

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If you guys trash one of your ECUs and need a replacement, let me know I'm going to be replacing mine in a couple of months and will have one for sale... :) low miles hehe
 

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I usually don't chime in around here, more of a spectator, but having a computer background I will add my two cents. Marcucci as dead on with regards to reprogramming our chip, it is "practically" out of the question. What would be interesting is trying a piggy back method. I spend some time with DTV test cards and piggy methods work well on bypassing sections of data that have been zapped. Although I feel it would just be much easier and cost effective to go ODB1, I would go the piggy route if I were going to make an attempt.... Just my 2 cents.

Jamez

I should stop looking at this thread before I get interested myself!

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Can we please put this in the FAQ? Good stuff...
 

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BTW guys (Todd, Billy):

Do you know of ANYONE who offers a REAL scan tool for the OBD-I Prelude ECUs? It's about time I do some real tuning--I'd like to monitor injector pulse width, spark advance, MAP values, manifold temps, etc. Heck, this has been easily available to most GM cars since the '80s; I'm surprised few have cracked the code to my ECU. Have any contacts?

Roger
 
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Originally posted by Lude_conduct:
BTW guys (Todd, Billy):

Do you know of ANYONE who offers a REAL scan tool for the OBD-I Prelude ECUs? It's about time I do some real tuning--I'd like to monitor injector pulse width, spark advance, MAP values, manifold temps, etc. Heck, this has been easily available to most GM cars since the '80s; I'm surprised few have cracked the code to my ECU. Have any contacts?

Roger
Never seen one for the Prelude.

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Billy
North Texas Prelude Owners Group
www.ntpog.org
 
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