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  • Confused about OBD-II Tuning/Programming...

    I'd appreciate it if someone could give me some advice. I can't seem to figure out how exactly OBD-II works.

    My goal is to create tuning software. I know and understand that I need to first write a program to receive the ECU data, via OBD-II. From there I can tune/make changes via my software. I do not want to write a diagnostic tool, but a tuning tool.

    My main question, what kind of cable do I need to receive all data from the ECU (the data that contains special parameters like the transmission type, injector flow rates, etc.)? What kind of chip supports this? The ELM 323?

    Thanks,
    Stephen

  • #2
    standard obd is mainly read only (you can only reset the check engine light). Different manufacturers have different, usually unpublished, proprietary protocols.

    there is lots of talk of this, around a bit

    |V1 Virtual Display|

    Hard work often pays off over time, laziness always pays off right now.

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    • #3
      Well thanks for the info After looking around a bit, I found screenshots of LS1 Edit by carputing. This is exactly what I'm trying to accomplish. Read PCM data in -> tune it -> Reflash the PCM with the changed data.

      I just don't understand. Can I use the ELM chip? Will it do this for me?

      I have 6+ years of programming, I'm not worried about that part. What I cannot seem to find is ANY information on acquiring the data via OBD-II and re-sending the data via OBD-II.

      Anyone with more information, please post it. I'd really appreciate it.

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      • #4
        If you have a honda try uber-data, nice software, datalogging, but you have to mod your ECm, oh and you'll have to get rid of it and go to obdI, otherwise you can just buy a converton cable, and at least get stats on your car.

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        • #5
          Originally posted by sschkade
          Well thanks for the info After looking around a bit, I found screenshots of LS1 Edit by carputing. This is exactly what I'm trying to accomplish. Read PCM data in -> tune it -> Reflash the PCM with the changed data.

          I just don't understand. Can I use the ELM chip? Will it do this for me?

          I have 6+ years of programming, I'm not worried about that part. What I cannot seem to find is ANY information on acquiring the data via OBD-II and re-sending the data via OBD-II.

          Anyone with more information, please post it. I'd really appreciate it.
          The elmscan will not. Every manufactuer is different. For instance, I've got a Chrysler Sebring Coupe (basically a bigger Mitsu eclipse).

          To program it you need two things.
          1.DRBIII which are $thousands.
          2. SRBIII ST-22 Supercard (~$100)
          A SRT8432 MMC Reprogrammer ~$800

          I actually have the later. (Yeah ebay! $50 )

          Just illustrating that all the mfgs are different.

          Now for the good news. There is a mandate saying that all newer cars ( believe 04+) must have an easy to use interface and be accessible to customers cheaply and easily. And they must be able to do it via a PC. This goes for flashing as well.

          I'll try and dig up my links for it. As far as I know, no cars support it yet. But should be coming down the pike soon.

          You can always get an emanage or SAFC-II in the meanwhile.
          GE Cache Builder | [email protected] |Coolstuff :autospeed.com | bit-tech.net | Nitemax Ultra Pinouts

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          • #6
            Hello shotgunefx!
            GREAT Information. I really appreciate your help. With these tools would I be able to create a generic piece of software? For example, I have a 2002 Chevrolet Silverado with a V8 - 5.3L. If I obtain all of this information, would it give me the offsets in the PCM data? Are the offsets consistant throughout all 2002 Chevrolet Silverados (V8 models)?

            I'm trying to write some generic software kind of like LS1 Edit, however I'm not looking to make profit. Just want a tool for myself, and I would contribute to the community (free, minus the cable/translator)...

            I've used my friend many many times now, and I just cannot find any information. I've found plenty of information on using OBD-II and writing DIAGNOSTIC tools, but I cannot seem to find anything on tuning. I'm very glad you are here to assist me with whatever you are willing to offer!

            Thanks, hope to hear more information soon!

            Hey dingofarmer! No honda here, sorry & thanks for the info!

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            • #7
              Originally posted by sschkade
              Hello shotgunefx!
              GREAT Information. I really appreciate your help. With these tools would I be able to create a generic piece of software? For example, I have a 2002 Chevrolet Silverado with a V8 - 5.3L. If I obtain all of this information, would it give me the offsets in the PCM data? Are the offsets consistant throughout all 2002 Chevrolet Silverados (V8 models)?

              I'm trying to write some generic software kind of like LS1 Edit, however I'm not looking to make profit. Just want a tool for myself, and I would contribute to the community (free, minus the cable/translator)...

              I've used my friend many many times now, and I just cannot find any information. I've found plenty of information on using OBD-II and writing DIAGNOSTIC tools, but I cannot seem to find anything on tuning. I'm very glad you are here to assist me with whatever you are willing to offer!

              Thanks, hope to hear more information soon!

              Hey dingofarmer! No honda here, sorry & thanks for the info!

              If your refering to the tools I listed for my car, then no. Those are the tools for my specific car (though the drbIII is for all dodge/chrysler). Your going to find that all the cars vary, even within the same mfg. I think that will change in the next 10 years, but for now, it's every car for itself.

              Even for my car, the tools I listed are still useless until I get a copy of the rom and then I still have to figure out where the maps are and what the data means. Took me a lot of digging and some luck to get what info I do have btw.

              When they get around to the 04+ open SAE thing (I haven't had a chance to look up the info again), it will help because you'll be able to get the rom and upload it yourself cheaply. But even then, need to undo any encryption there is and then figure out what the actual rom contains and what you want to change. No easy task. The companies don't want anyone knowing what the rom contains (timings,maps,etc). They fought this and companies like autozone and a few others ganged up to fight for access which is I believe how the whole SAE thing I was talking about came up. So I don't think you'll find any car mfg that will point out the interesting tidbits. Another roadblock is that the ecus for cars are usually commodity microcontrollers with some added instructions. So if your lucky, you might be able to get some headway using the documentation for the regular line that company produces, but there is a good chance that some of the opcodes and whatnot only exist for that car and you won't ever figure out how those little bits work.

              Your best bet is to probably go for something like an SAFCII or E-Manage and tune yourself. They basically sit inbetween sensors and manipulate the signals for the desired effect. The unit stays in the car permanently to keep the effect. You could give other users of the units the "tune" you wrote.

              I don't think without lots of research, work and a good deal of luck you'll be able to do anything directly to the ECU.

              Just so you know, I'm far from knowlegdable in this area. I know a lot about my specific car (and a little about the rest) simply because I have the same urges as you do. I haven't given up, but it's going to be something that happens over a couple years.

              I don't know if you've done much tuning, but you can do quite a lot of damage to your engine playing with the fuel maps. Not saying you will, just saying it to say it.
              GE Cache Builder | [email protected] |Coolstuff :autospeed.com | bit-tech.net | Nitemax Ultra Pinouts

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              • #8
                Just for accuracy sake - the DRBIII is for non CAN protocol Chrysler Group product. The newer StarScan is for CAN vehicles. For Chrysler Group, the 2004 Durango was the first CAN vehicle. Not every vehicle after that is CAN. For 2005 about 50% of Chrysler Group vehicles are.

                There are lots of vehicles that support Flash. Chrysler Group supported flashable ECUs for many years now. I think you are refering to "Pass through Programming". Ease (www.obd2.com) is now selling a pass through programmer. You get the flash files from the OEM, and use the programmer to send that binary to the vehicle's ECU(s). A reprogrammer will not be "cheap" if you are not in the business of vehicle repair. At least $3k plus the subscription cost of the binarys.

                One of the major reasons an OEM won't divulge info on the contents of the Flash is that the Flash files are EPA certified. Dinking with them will invalidate the certification. It would be a very significant effort to be able to effectively modify the flash file for performance gain. In the learning process, you stand good chance of trashing a lot of ECUs.

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                • #9
                  Originally posted by DavidL
                  Just for accuracy sake - the DRBIII is for non CAN protocol Chrysler Group product. The newer StarScan is for CAN vehicles. For Chrysler Group, the 2004 Durango was the first CAN vehicle. Not every vehicle after that is CAN. For 2005 about 50% of Chrysler Group vehicles are.

                  There are lots of vehicles that support Flash. Chrysler Group supported flashable ECUs for many years now. I think you are refering to "Pass through Programming". Ease (www.obd2.com) is now selling a pass through programmer. You get the flash files from the OEM, and use the programmer to send that binary to the vehicle's ECU(s). A reprogrammer will not be "cheap" if you are not in the business of vehicle repair. At least $3k plus the subscription cost of the binarys.

                  One of the major reasons an OEM won't divulge info on the contents of the Flash is that the Flash files are EPA certified. Dinking with them will invalidate the certification. It would be a very significant effort to be able to effectively modify the flash file for performance gain. In the learning process, you stand good chance of trashing a lot of ECUs.

                  Part of their argument was the timings and what not were proprietary. I new StarScan was new, but wasn't sure of the signifigance. Thanks for the info.

                  I'm lucky, if I can find my flash file, I know of another car that has everything the same except the fuelmaps + timing. A simple diff should revel the interesting tidbits.

                  Here's a little blurb about that mandate I was talking about. I'm quoting a post I wrote in September.
                  All about J2534: Free Markets, Pollution and the Automobile industry.

                  The EPA has mandated that all 2004 model cars must support the SAE J2534 standard. What is this new standard and what does it mean for you?

                  Until now, only auto dealers were able to upgrade the ECU firmware with tools that sometimes cost as much as the car itself.

                  Starting with model year 2004, the EPA wants anyone (including auto repair shops and car enthusiasts) to be able to upgrade their car "for a reasonable cost." To accomplish this, they asked SAE to create the J2534 API.
                  ...

                  The Software
                  The EPA is forcing car manufacturers to release software that updates the firmware on their cars. The application must run on Windows and use the J2534 API to talk to the car. Anyone can buy this software, even individual car enthusiasts. The software must be sold 'for a reasonable price', which will probably be a few hundred dollars.
                  GE Cache Builder | [email protected] |Coolstuff :autospeed.com | bit-tech.net | Nitemax Ultra Pinouts

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                  • #10
                    Here is a reprogrammer that is now available:
                    http://www.obd2.com/J2534/index.html
                    The definition of "reasonable" was not defined by the Feds. Knowing what's under the covers of the hardware that is needed and the volumes, It won't be in the hundreds of dollars. I suspect Reasonable will be defined by competition of tool providers and their competitive pricing to gain market share. End users will also be able to have their vehicles flashed at a lower price, simply because there will be more places that can perform a flash (non dealers). This isnt' to say that End users will purchase a device to flash their vehicle at a "reasonable cost". I am also sure that the EPA doesn't want folks messing with the Flash binary! The cost of access to the binary files will be reasonable. Most OEMs are providing access to the flash files via their Service Information Library websites (almost all are subscription based websites).

                    BTW, the StarScan does not support J2534. So, you cannot plug a StarScan into a Chevy and flash it.

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                    • #11
                      check this site for info
                      http://www.hptuners.com/forum/YaBB.pl
                      Mostly gm info but some other.I have this software and it is great.

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