Relative Fuel injector flow testing

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  • Witsend
    Banned
    • Nov 2012
    • 2942

    Relative Fuel injector flow testing

    Ford has had this test available in house since the 90s in days of the SBDS (Service Bay Diagnostic System),running off something like Windows 98 , but testing in those days required a fuel pressure transducer.
    Fast forward through WDS , and presently with IDS (Integrated Diagnostic System), return less fuel systems with Fuel Rail Pressure sensors , a fuel pressure transducer is no longer required, and I'm sure this special function could be added along with relative compression ,and power balance to most bi directional aftermarket scan tools. Even on The Ole hole filler DS 708 that does have power balance feature available but I did not see any more options on it for relative compression , and relative fuel injector flow, so I don't think Snappy offers it yet either since Ford isn't suing Snappy besides Autel yet?
    You would think that scan tools would have evolved to have incorporated these very useful tests into them by now. Who would think after nearly 25 years of dropping quarters in the Juke box for Singing and Dancing to " Whole Lotta Shaking Going On", sooner or later a China man is going to say That's Wong Enough and gonna burn a copy mixed with Gong Nam Style and sell a Million Bootleg Copies in a couple months.



    Last edited by Witsend; 12-11-2014, 11:24 AM.
  • Witsend
    Banned
    • Nov 2012
    • 2942

    #2
    Does any aftermarket scan tools offer relative compression testing, and relative injector flow testing at the present?

    Comment

    • Crusty
      Senior Member
      • Dec 2007
      • 2450

      #3
      Originally posted by Witsend
      Does any aftermarket scan tools offer relative compression testing, and relative injector flow testing at the present?
      Relative compression testing is just a matter of monitoring the battery voltage or starter current closely when cranking.

      Comment

      • Witsend
        Banned
        • Nov 2012
        • 2942

        #4
        Relative compression testing is just a matter of monitoring the battery voltage or starter current closely when cranking.
        My Counselor 2 has been used to perform relative compression tests on conventional ignition systems fine using #1 spark plug wire inductive pickup and the high amp probe, but I get a blinking error message triing to do the test on DIS waste spark ignition systems and some coil on plug ignitions because the #1secondary pickup is just too bulky to fit in tight areas to access the primary wire to #1 and the Coil primary might not generate a strong signal for the secondary pickup to work all the time. I'm tempted to try the relative compression test on a waste spark system and select and run the test in 2 stroke mode. What happens when testing a Saab 9-3 missing a tooth on a Bosch ring gear, that has a Lucas starter solonoid , turning a rebuilt starter with a french commutator with japanese brushes on a starter with a GM part number? Can you test the results?
        Last edited by Witsend; 12-11-2014, 05:56 PM.

        Comment

        • Crusty
          Senior Member
          • Dec 2007
          • 2450

          #5
          Originally posted by Witsend
          My Counselor 2 has been used to perform relative compression tests on conventional ignition systems fine using #1 spark plug wire inductive pickup and the high amp probe, but I get a blinking error message triing to do the test on DIS waste spark ignition systems and some coil on plug ignitions because the #1secondary pickup is just too bulky to fit in tight areas to access the primary wire to #1 and the Coil primary might not generate a strong signal for the secondary pickup to work all the time. I'm tempted to try the relative compression test on a waste spark system and select and run the test in 2 stroke mode. What happens when testing a Saab 9-3 missing a tooth on a Bosch ring gear, that has a Lucas starter solonoid , turning a rebuilt starter with a french commutator with japanese brushes on a starter with a GM part number? Can you test the results?
          LMAO -!! YES,.....it's called BOOM-!!!! LOL

          Comment

          • maven
            Senior Member
            • Mar 2014
            • 269

            #6
            I have never needed a relative compression test on an OBD2 vehicle. If theres a base engine mechanical issue so serious that it definitively shows up on a simple relative compression check then its gonna show up on the ECM data. And ill be able to get to the cylinder I need to and do proper physical testing quicker

            Non misfire monitor vehicles....thats a different story. Ill throw a scope on the vehicle and see what it shows.

            As far as "relative injector" testing. Ive never heard it called this, but GM has offered in on the Tech2 basically since the Tech2 was released(and now the GDS2). It does require a physical fuel pressure gauge though on many vehicles. And I believe the big name scan tools provide this functionality on most of the GM vehicles that support it as well.


            Wit, I still never get over (or 100% understand) your many odd and loquacious posts. Id love to know if its just some affectation youve developed or if perhaps its caused by something environmental, such as self administered liquids or pills, or perhaps excessive exposure to a shop chemical.

            Comment

            • Witsend
              Banned
              • Nov 2012
              • 2942

              #7
              It might be MGD

              Wit, I still never get over (or 100% understand) your many odd and loquacious posts. Id love to know if its just some affectation youve developed or if perhaps its caused by something environmental, such as self administered liquids or pills, or perhaps excessive exposure to a shop chemical.
              Reply With Quote
              "My General Disposition" is never take life too seriously and I also tend to still be a Button Pusher in a Touch Screen World.
              Just be nice to be able to sit in any car line and do the relative compression testing from driver's seat , show the customer the compression deficit, and ask for additional time then hooking up an oscilloscope and high amp probe or accessing a plug at the back of engine compartment. Easiest and least invasive testing to start with is preferable.
              Last edited by Witsend; 12-12-2014, 09:54 AM.

              Comment

              • maven
                Senior Member
                • Mar 2014
                • 269

                #8
                Dont need to access a plug at the back of the engine...all you need is any accessible signal that is firing order based. doesnt matter if its fuel injector or secondary or primary ignition, bank 1 or bank 2. just need to use it show a sync. then just work your firing order from that cylinder instead of #1.

                And if Im gonna rely on a relative test for diagnosis or asking for money then I want one using a device that actually measuring the condition....and not trust a calculation done in the scan tool based on data transmitted from a module that is calculating everything in a car that I already know is broken. Too many variables for me to trust an onboard relative compression test like that, especially since I as I mentioned the misfire data is already going to point you to the problem cylinder and I can just ask for proper diagnostics up front.

                And hell if you really wanna get lean on your diagnostic approach, just hook up your scanner or scope and have it graph voltage as you crank....thatll give you close enough information and itll look just like an RC test would to the average customer...abunchasquigglylines

                Comment

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