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Hacking up Honda's ECU
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PostPosted: Fri Apr 11, 2003 1:11 pm 
Ok, here's the problem...actually, it's a recurring issue for me, but something new has developed that has me stumped.

I have a '90 JDM ZC in my USDM '90 CRX. As so many others have done, I found myself a '91 (USDM) PM6 and chipped it, then burned a PM7 program (PM7ZCORG69.BIN) to it, and love it. After running a PG7 ECU for a few months, the PM7 program seemed to breathe new life into my engine. With the advent of Ghettodyne 1.4, I wanted to be able to use the new features (in particular, launch control and ECUControl) so I began splicing the maps from the PM7 proggy into the Ghettotune bin. There are a number of entries in the PM7 ignition maps that indicate more than 40 degrees of timing retard (starting with 2200 RPM/21 In Hg = 43.19 Degrees), however if you try to enter these values, Ghettodyne throws an error stating that you can't retard your timing more than 40 degrees. I notified Mike of this issue, which he planned to resolve in GHD 1.5. For the moment, the problem still exists (bugfix didn't make it to the release) and Mike claims it will be fixed in 1.6. Ok, enough background, here's where things get interesting...

Being impatient, I decided to try to work around ghettodyne and edit the values in question in hex...which worked. I was able to use the ignition > hex formulas and plug in the values to my rom, which opened fine in ghettodyne 1.5, and as long as I didn't attempt to change them, threw no errors. Excited, I burned this new bin to a chip and went for a test drive. All was well, no CEL or codes, until I noticed an odd problem. Everything would be cool, and all of a sudden my injectors would cut out (A/F guage went blank) and the car would start bogging like it was out of gas...I noticed this first at part throttle while heading up a hill. Oddly enough, if I opened the throttle more, the problem went away and injectors kicked back in. Initially thinking I had a problem with my fuel maps, I re-checked and they were cool. Went for another test drive, and this time paid attention to RPM and throttle position. I realized that my problem was directly related to the entries in my ignition maps, and whenever the situation (RPM + Load) called for more than 40 degrees of retard the car would take a shit...opening the throttle more would decrease the vaccum and take me out of the -40 range. Here are my suspicions:

1. I screwed something up while editing the bin in hex.
2. Ghettotune.bin is written in such a way that it doesn't allow for more than 40 degrees of retard, and is crapping out when it receives instructions to do so. Mike must have come up with this limitation in GHD 1.4 for a reason, and I'd like to know why as it may shed some light on this issue.
3. PM6 programs don't allow for more than 40 degrees of retard, while PM7 programs do. (shot in the dark)

I appreciate any feedback on this, as it's beyond my skills to investigate any further. If this doesn't belong in the development forum, I apologize ahead of time.

Thanks, -Z


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PostPosted: Fri Apr 11, 2003 1:31 pm 
well, have you tried limiting your retard to 40 degrees and then seeing if that much retard is really necessary?

I don't think you would have #1'ed it too bad, else I would think it would crap out at other times, too.

#3 could very well be, could cause math to go bad (like dividing by zero)...

can't comment on #2...

[%sig%]


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PostPosted: Fri Apr 11, 2003 3:55 pm 
I tried using the PM7 fuel maps along with the PM6 ignition maps, and while it worked and the car ran well, I noticed a distinct loss of power throughout the power band. So to answer your question, I haven't tried just capping the entries at 40 degrees and leaving the others the way they are, mostly b/c I'd like to have the ignition maps identical to the stock PM7 for a base tune. The way I see it, a stock engine should run best with the stock program designed for it...know what I mean? -Z


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PostPosted: Fri Apr 11, 2003 6:34 pm 
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Joined: Tue Jul 27, 2004 2:09 am
Posts: 148
Location: New Zealand
Couldn't you cap all the values at 40deg, then edit the .bin after running it through Ghettodyne (remembering to keep the checksum gods happy of course).
You can easily enough check for #2 by comparing the GhD'd ignition map with a stock one. If it is, just copy the ignition maps straight over from the PM7ZCORG69.BIN you have, then correct for the checksum.

It won't be #3, people have been running full PM7 maps just fine in their PM6's for a long time.
#1 is a possibility, but check for #2 first.

George


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PostPosted: Fri Apr 11, 2003 10:03 pm 
George, I did exactly what you suggest (cap the values at 40deg in GHD, save, then edit in hex and correct the checksum), and it resulted in this issue.
I opened up a stock PM6 bin in winhex and also opened up ghdmodified.bin in GHD. In GHD 1.5, it shows the offset for the ignition maps at 03DFF. If I search for that position in the PM6 bin, the first value is 1A, or (after doing a hex to ignition conversion) 3.96. If I search for this offset in ghettotune.bin, I find 3C, or 16.2. So it appears that the offset I got out of GHD 1.5 is only valid for GHD roms. If this is what you mean by different, then it's different :). -Z


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PostPosted: Fri Apr 11, 2003 10:58 pm 
Ok, you caught me in a good mood...try this new executable, and GhettoTune.bin

Mike


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PostPosted: Mon Apr 14, 2003 10:48 am 
Sweet...Mike, you are the man!!! I'll test this out as soon as I can, unfortunately I put a chip in my batronix eeprommer backwards and burned out a transistor, replaced it with what I thought was an equivalent one from rat shack...heh, well, as soon as I plugged it back in a plume of smoke started rising from the transistor and before I knew it, the traces on the PCB were scorched. So I'm dead in the water until then. Thanks again man...-Z


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PostPosted: Mon Apr 14, 2003 8:07 pm 
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PGMFI Elf

Joined: Tue Jul 27, 2004 2:10 am
Posts: 917
Location: ashEVILle, NC
I just (finally) got around to reading Zac's original problem. Does it sound familir to you, Mike?

[%sig%]


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PostPosted: Tue Apr 15, 2003 10:48 am 
Whoops, just realized that my last post didn't make any sense...my burner's broke and I'm waiting on a new PCB from Batronix. Once it's fixed I'll test this new version out. -Z


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PostPosted: Wed Apr 16, 2003 1:06 am 
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PGMFI Elf

Joined: Tue Jul 27, 2004 2:10 am
Posts: 917
Location: ashEVILle, NC
Error when writing to offset 0?

[%sig%]


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PostPosted: Fri Apr 18, 2003 10:23 am 
"Error when writing to offset 0?"

Nah, it was something like "sector 255 cannot be programmed, please check the EEprom and hardware" I did the batronix hardware test, and I was reading 19v at pins 1,3 and 28, regardless of what voltage was supposed to be fed (5v, 0v, and 12v). Thought it was my voltage regulator and replaced it, still the same problem. Isolated what appeared to be a faulty transistor and replaced it, but the board's toast now, so I guess I'll never know :(. -Z


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PostPosted: Sun Apr 27, 2003 6:16 pm 
Ok, finally got my burner fixed, and I tried out the new rom I made via GHD 1.6...getting the dreaded CEL after 45 seconds, checksum? Bad jump? I'm out of my element. -Z


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PostPosted: Sun Apr 27, 2003 6:35 pm 
Can you send me a copy of the bin you made that is giving you the CEL?

support@GhettoDyne.com

Mike


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PostPosted: Sun Apr 27, 2003 11:48 pm 
Just emailed it to you. Thanks again, -Z


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PostPosted: Mon Apr 28, 2003 9:21 pm 
Question: Does it do this with the stock un-altered GhettoTune.bin file that comes with 1.6?

Mike


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