Quote:
Originally Posted by DBFIU
Hello Blueroadster and Hirev1, much appreciation for your efforts thus far.
Although I am new to imports I have some advice for you. If you plan on designing a standalone that will have control or access to engine inputs such as, injector pulsewidth, fan on/off?, timing, VTEC? etc... You must remember that unless you have the actual code (software for the ECM) you will not know which parameters are reliant on some 'bullshit' parameters that will make your life hell.
What I'm trying to say is, because it is such an electronic engine, finding out if opening your sunroof will change the timing of the motor will be very important. Now I'm not saying that is the case, but you will see that honda ECMs have hundreds of input parameters. If you cannot simulate any of these parameters OR retain them as inputs in your new ECM standalone; you will run into a lot of problems. I would like to help you guys with this project.
- Dan
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I don't have time to build a standalone. The intent of this thread was to put our minds together and figure out as much as possible to help the tuning community offer a sound programmable solution.
Anyone that has the Honda Diagnostic Software (HDS) already has the acutual source code for all OBD Honda and Acura vehicles. There are seperate files for the various years/makes/models. Each file is saved with a .rwd extension, is less than 1 MB in size and uses a substitution cipher on the payload programming portion. When a .rwd file is written to an ECM, it is done so through the use of a Honda Interface Module (HIM) or other Honda approved pass through device. The HIM knows the substitution cipher used on the .rwd files and writes the cleartext data directly to the ECM.
If you don't want to waste the time trying to figure out the substitution cipher used, then you would need to read the data currently stored on the ECM in flash memory. That way, you could extract the 1 MB of data in pure form. I already posted a link earlier regarding the microprocessor used in the ECM. There is technical article in that link that details how to read/write data to the flash memory on or off board.
Once you get the data, the next hurdle is trying to decipher each value. Hondata clearly understands this part as they can change specific values as per their reflash offering. If you have deciphered many of the values, you would then need to understand the programming dependencies. For example, I have heard that the rev limit value is stored in multiple locations in the code. You must change all stored values for the rev limit in order for the change to take effect.
With that being said, this isn't something one could figure out in their garage over the weekend. Even if I completely understood how to manipulate the code in the ECM, I would still not want to develop a product. Why, because then I would have to design a software user interface and a hardware device to then sell to the general public. Hondata, AEM, Haltec, etc. have invested years into their products and I would not want to attempt to even try to compete with what they have done. What I would rather do is to share information that would hopefully help the tuning world develop something for us sooner.