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Hacking up Honda's ECU
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PostPosted: Sat Jun 28, 2014 10:44 am 
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Finally sat down last weekend and got everything laid out on the breadboard and working 100%.

Image

Ended up using two minis, they take up less board space than I would take up using two sockets/controllers/crystals/etc. It's also easy to reprogram in-situ with an ftdi breakout cable and they have their own reset switches. The one on the right handles VSS via a TIP120 transistor and the one on the left handles the distributor signals via the MAX235 chip. The MAX235 is a little expensive (Maxim will send you a free two piece sample though) but it has five level converters and internal caps so it makes a nice clean install.

The rest of the board looks the same for now:

Image

That was my first attempt at using a perfboard so don't judge too much :)

Works well so far but it's a little clunky since it's a big mess spread out over two boards. Spent the bulk of last weekend just using it, all I really wanted was to pick apart the serial packets coming from my Demon. I'm going through and laying everything out in Eagle now. I may or may not do anything with it but I want to at least get it all documented.


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PostPosted: Mon Jun 30, 2014 11:12 am 
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If you at least have a hand drown schematics, send it to me, I'll try to make a layout out of it.


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PostPosted: Wed Jul 02, 2014 12:30 pm 
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Thanks, I'm already chugging through it all in Eagle. Only way to learn is to do, right?


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PostPosted: Mon Jul 14, 2014 12:35 am 
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So I guess you weren't getting code 9 with this board that I can create on ANY OBD1 ecu using the moates engine Sim.

(Check rpm around 2000-2500 and again at 6000rpm ish for injectors getting out of sync) Then code 9 if you transistion out of 1800-2500 too many times


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PostPosted: Mon Jul 14, 2014 5:21 am 
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Why you have used two Arduino module when one is enough for everyone to do :?:
spAdam wrote:
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PostPosted: Wed Jul 16, 2014 11:34 am 
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I wasn't good enough at programming so I made up for it with more hardware :)

In all seriousness, one handles the distributor sim and the other handles VSS. I haven't seen anyone else doing VSS pulse. I'm sure there's a way to pull it off with one but I just wanted to get it working so I could finally use the damn thing.


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PostPosted: Fri Aug 01, 2014 8:37 pm 
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What is the minimal set of signals to get the ECU to start sending out ICM signal on a bench?

I am using stm32f4 for my controller and MAX232 for zero crossing. I've generated the three VR signals which seem to be close enough and powered the ECU with +12. The ECU does output +5v on TPS/MAP vcc lines, I also see that my signal gets processed by the VR conditioning circuits - I've connected logic analyzer to HIC1 pins 10, 12 and 17. What am I missing? I would expect something on line A21 - ICM Output - but nothing so far.

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Image

I guess I should figure our how to get the check engine line to blink out a code.


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PostPosted: Sat Aug 02, 2014 5:47 am 
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Output ICM is open collector ouput.
Add pull up resistor to +12v (ex: 1k)


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PostPosted: Sun Aug 03, 2014 10:37 am 
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Yep. Iirc (board is put away right now) I had to use a 3.3k resistor before I stopped getting ICM errors.

I also found that running the icm on its own loop (A21 --> LED --> resistor --> A23) with nothing else on that ground helped with stability for whatever reason. Otherwise it would run for only a few seconds before throwing a code.


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PostPosted: Mon Aug 04, 2014 10:47 pm 
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dip wrote:
Output ICM is open collector ouput.

Ohh, right - this explains everything! I've got the ICM signal, thank you!

Do you guys know anything about transmission control signals? I am having some ~40Hz noise on the trigger lines when I am trying to use my own standalone - see viewtopic.php?f=6&t=23979&p=138991#p138991 for details


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PostPosted: Wed Aug 13, 2014 9:06 pm 
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So I am sending out three signals using MAX232 and the ECU does respond with some ICM signals - but ICM control mode is pretty much repeating my TDC signal. I am trying to apply different voltage at MAP sensor input wire but timing stays the same. I wonder if my ECU is in some sort of limping mode?

The shape of the signals I generate is visible in my previous message. Any suggestions?


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PostPosted: Thu Aug 14, 2014 2:29 pm 
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russian wrote:
The shape of the signals I generate is visible in my previous message. Any suggestions?
I'll check, on my system, the phase of the three signals, and compare if it corresponds to the phase of yours.

:arrow: Phase CYL/DTC/CRK est very importante


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PostPosted: Sat Aug 16, 2014 11:04 am 
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dip wrote:
:arrow: Phase CYL/DTC/CRK est very importante


Pulsewidth too. It's all about getting the zero crossings lined up in a way that the ECU recognizes it. It took a little bit of playing around to get it to a place where it was really stable.


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PostPosted: Sat Aug 16, 2014 1:41 pm 
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Attachment:
My Timing and Phase.png


You do not have the required permissions to view the files attached to this post.


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PostPosted: Thu Aug 21, 2014 8:33 am 
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dip wrote:
Attachment:
My Timing and Phase.png

Thank you Dip, I really appreciate the picture! I've just implemented the same signal shape.

Looks like my under-provisioned 0.1uF caps on max232 cannot keep up with idle RPM, waiting for 1uF caps to show up on Monday.


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