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98 GM 6.5 Diesel & 04 GM Duramax interface cable

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  • 98 GM 6.5 Diesel & 04 GM Duramax interface cable

    I currently own a 1998 Chevrolet 6.5 turbo diesel, and my brother owns a 2004 Chevrolet Duramax. The 98 is touchy when it comes to turing up boost pressure so a manual or electronic gauge isnt always as reliable for aftermarket performance upgrading as what the ECU is reading. So now i'm interested in purchasing an interface cable along with a downloadable program to read the ECU for external performane tweeking, and then rely on my aftermarket gauges for any day to day abnormalities.

    This brings me to my question... What cable (Usb not serial, as my laptop doesnt have serial) do i need for this 98 truck, (OBD II J1850 VPW?), and what cable would work with the 2004 Duramax... or in a perfect world... what cable would work with both vehicles?

    Thanks in advance

  • #2
    elmscan 5 compact.

    "Supports all legislated OBD protocols:

    * ISO15765-4 (CAN)
    * ISO14230-4 (Keyword Protocol 2000)
    * ISO9141-2 (Asian, European, Chrysler vehicles)
    * J1850 VPW (GM vehicles)
    * J1850 PWM (Ford vehicles)


    • #3
      If you are interested in doing some datalogging from both of these vehicles, you might try our ScanXL software ( It offers a GM enhanced add-on that supports enhanced powertrain sensors for both of these vehicles.

      ScanXL is a datalogging product only. It cannot do any tuning/reflashing.
      Brian @ Palmer Performance Engineering, Inc.


      • #4
        Very tight, now being as these vehicles are both diesels, is there anything that the software would normally work for on a gas but won't work for with the diesels?


        • #5
          yah, PPE's right, all those softwares do is datalog. to reflash the ECU it has to be reflashable, and someone has to reverse engineer the ECU to be able to communicate with it, write it, and get it to pass CRC/checksum checks otherwise the ECU will fail to work.

          why don't u check out bullydog or banks tuning? yes i know their piggybacks are far from optimal (load one of their 3 flashes) and expensive ($300)

          bullydog and banks tuning charge what they do for their products because they paid $$$ to someone in the form of R&D to dissect the ECUs of these vehicles and write programs to communicate with them.


          • #6
            Couple of things:

            1. PPE --> If i was to use the scanXL software with the appropriate hardware since both of these trucks are diesels, is there anything that the program won't be able to do (that it would otherwise do fine with a gas)?

            2. CTdubbin --> I couldnt agree more with you on going for a bullydog/banks/edge/efi live etc set up, BUT the only problem is my 1998 6.5L turbo diesel doesnt have the options that the duramax's, cummins', or powerstrokes have... What do i mean? There is NO company that has made a plug and play chip for my truck and by that i mean ZERO. The only way i can "chip" my ecu is by manually taking the ECU box out, and sending it away to various companies that flash them with what ever program you desire ( has captured the 6.5 diesel market) and i will likely go with his product when i've done enough modifications that chipping is necessary. Only thing is i wont have the heads up display option that bullydog or any other company offers, and since boost pressure with these things is so touchy, i need to know exactly what my ecu is reading, not a unreliable gauge.... With these trucks you can run 15psi and not have a problem (i know a joke compared to the 35+psi a cummins can handle), but a friend of mine had his set to 15psi on his isspro gauge, and blew his head gaskets... he then hooked into his ecu and found out he was running 17psi.... just 2psi is enough to cause a big headache... These are the reasons why i'm looking for the laptop to ecu set up (for checking and/or verifying my gauges)... i'm not going to have the laptop in my truck at all times, that'll just get annoying.

            The reason why i want one that will work with the duramax as well, is just so that i dont go out spending 'x' dollars for a set up that is only good for my truck or my era of truck, when i could have spent 'y' dollars on something relatively universal.


            • #7
              There is really nothing that ScanXL won't do on a diesel that it would do on a gas engine, other than the typical things like catalytic converter PIDs and O2 sensor PIDs, etc. Things the diesel engines don't have.

              With the GM enhanced add-on, ScanXL will have many more PIDs for your vehicle, and with a suitable hardware interface, it will even let you read/clear ABS and airbag trouble codes. You'll also get transmission PIDs too!

              About the boost reading, ScanXL will report the boost value that the ECU is telling it. If you've got a piggyback system that is giving the engine more boost than the ECU knows about, ScanXL will not know about the extra boost either.

              Good luck with your tuning efforts!
              Brian @ Palmer Performance Engineering, Inc.


              • #8
                Very cool. The boost that it is currently set at is about 8 psi, but its a vaccum controlled wastegate, which i can adjust by getting rid of the vaccum control and putting a "turbo master" that basically holds the wastgate closed with a spring... tighter you crank on the spring the more boost it will send to the engine, so there is no fear of the ecu not getting a proper reading (not tricking the ECU... yet). The stock program will code after about 12psi, so until i get my ECU flashed by Bill Heath to turn up my pump, and allow the extra boost, i dont plan on going past 12psi... or fooling the ECU into taking 15psi... yet. Besides, plans are to drop the compression, and get the boost upwards to 25psi... big project over then next 5 years.

                Back to things that ScanXL will/won't do... i was reading that these programs have a hard time with milage calculations for diesels... is that true or yet another fallacy?


                • #9
                  Originally posted by Dylly View Post
                  Back to things that ScanXL will/won't do... i was reading that these programs have a hard time with milage calculations for diesels... is that true or yet another fallacy?
                  Now that is something I didn't think of. Our ScanXL software has a very advanced scripting engine where you can create custom Javascript parameters. We've included some built-in sample scripts that calculate fuel economy, but they are oriented towards gasoline vehicles.

                  So with that mind, our built-in sample fuel economy scripts would not work so well on the diesel. However, you are free to edit them and correct the calculations to work with your vehicle.
                  Brian @ Palmer Performance Engineering, Inc.


                  • #10
                    It's times like these that i wish i was a comp. sci. major instead haha


                    • #11
                      I use HP Tuners for scanning/tuning - covers a lot of GM vehicles, looks like it covers the Duramax but not the 98

                      If anyone gives me a rev - I give them the Bird


                      • #12
                        Rick99TAWS6 - That looks like a deadly program, but the priority is the 98, although the tuning for the 04 would be awesome, it looks as good as EFI live which is saying a lot, but if i cant use it on my 98, it's a pricey tool for what i'm looking for. Thanks for the reply/suggestion though.

                        So it looks like i'll have to talk to some comp sci majors and see if they can create some code for me if i decide to go with scanxl, which it seems like the obvious choice. Only thing is i dont know what a diesel engine uses to calculate fuel economy, i'm sure fuel flow rate and boost pressure would have to be variables, but i havent done enough research yet.