What do you use your pressure/vacuum transducer for?

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  • No-Start
    Senior Member
    • Oct 2006
    • 932

    #16
    Originally posted by Nick
    I use static and dynamic compression.
    That still won't show you a valve timing issue that affects the whole engine.

    No-Start.

    Comment

    • Nick
      Senior Member
      • Oct 2006
      • 550

      #17
      Originally posted by No-Start
      That still won't show you a valve timing issue that affects the whole engine.

      No-Start.

      The pressure will show it. For example. late exhaust valve timing will cause a higher reading.

      This has worked for me over the years with sohc v style engines and dohc v style engines.

      Your arguement is that a pressure transducer will show the pressure but a gauge won't. They both read pressure. i am not arguing against the transducer, just stating it can all be done without it.

      The time to learn how to properly and quickly read the waveforms from a tranducer was the subject of discussion.
      Mechanic-Instructor-Mobile Trouble Shooter

      Autotechdiagnostics.com

      Comment

      • No-Start
        Senior Member
        • Oct 2006
        • 932

        #18
        Originally posted by Nick
        The pressure will show it. For example. late exhaust valve timing will cause a higher reading.

        This has worked for me over the years with sohc v style engines and dohc v style engines.

        Your arguement is that a pressure transducer will show the pressure but a gauge won't. They both read pressure. i am not arguing against the transducer, just stating it can all be done without it.

        The time to learn how to properly and quickly read the waveforms from a tranducer was the subject of discussion.
        You could have a timing belt shift one notch that won't show a significant change in pressures. Try it for yourself and see.

        My argument isn't to read pressures with the transducer, as the pressure change isn't significant in some cases, that won't show the problem.

        My argument is that you can use the waveform and interpret breathing issues with that, that is something you can't do with a gauge.

        No-Start.

        Comment

        • Nick
          Senior Member
          • Oct 2006
          • 550

          #19
          Originally posted by No-Start
          You could have a timing belt shift one notch that won't show a significant change in pressures. Try it for yourself and see.

          My argument isn't to read pressures with the transducer, as the pressure change isn't significant in some cases, that won't show the problem.

          My argument is that you can use the waveform and interpret breathing issues with that, that is something you can't do with a gauge.

          No-Start.

          I have found timing belts off a tooth with a compression gauge.

          The most important part is having a consistent compression routine. On a v style engine the compression bank to bank will be off.
          On a straight style engine compression numbers will be either higher or lower depending on the actual mechanical timing.
          Mechanic-Instructor-Mobile Trouble Shooter

          Autotechdiagnostics.com

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          • No-Start
            Senior Member
            • Oct 2006
            • 932

            #20
            Originally posted by Nick
            I have found timing belts off a tooth with a compression gauge.

            The most important part is having a consistent compression routine. On a v style engine the compression bank to bank will be off.
            On a straight style engine compression numbers will be either higher or lower depending on the actual mechanical timing.
            I've compared readings on engine where the timing belts are off by a slight amount, the compression is off a slight amount as well. Definately not enough to make a call with it, especially due to the variances that you can get from engine to engine.

            V-engines don't necessaryily have inconsistencies from bank to bank if the valve timing is off equally on both banks.

            Coompression numbers will be off, but if they are all off a total of 10% say, could you say for any certainty that the cam timing is off? I highly doubt it.

            Using a compression waveform removes all doubt. That makes for faster and more accurate diagnostics.

            No-Start.

            Comment

            • Nick
              Senior Member
              • Oct 2006
              • 550

              #21
              Originally posted by No-Start
              I've compared readings on engine where the timing belts are off by a slight amount, the compression is off a slight amount as well. Definately not enough to make a call with it, especially due to the variances that you can get from engine to engine.

              V-engines don't necessaryily have inconsistencies from bank to bank if the valve timing is off equally on both banks.

              Coompression numbers will be off, but if they are all off a total of 10% say, could you say for any certainty that the cam timing is off? I highly doubt it.

              Using a compression waveform removes all doubt. That makes for faster and more accurate diagnostics.

              No-Start.

              Not to continue beating this dead horse. I have been using compression gauges for timing being off for a very long time. I can and do tell the difference when v style engine timing is off. Also keep in mind, When timing is off there are symptoms, once you have determined timing may be a cause, compression will confirm it.


              My point is the transducer is sampling the same exact cylinder pressure that a gauge does. Explain to me how the transducer itself removes all doubt. Once again, I am not saying they don't work.
              I was stating gauges are just as good, IMO.
              Last edited by Nick; 07-22-2008, 03:07 PM. Reason: sp
              Mechanic-Instructor-Mobile Trouble Shooter

              Autotechdiagnostics.com

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              • No-Start
                Senior Member
                • Oct 2006
                • 932

                #22
                Originally posted by Nick
                Not to continue beating this dead horse. I have been using compression gauges for timing being off for a very long time. I can and do tell the difference when v style engine timing is off. Also keep in mind, When timing is off there are symptoms, once you have determined timing may be a cause, compression will confirm it.


                My point is the transducer is sampling the same exact cylinder pressure that a gauge does. Explain to me how the transducer itself removes all doubt. Once again, I am not saying they don't work.
                I was stating gauges are just as good, IMO.
                I have seen many people "think" the timing is off and using compression testing, cannot confirm without any certainty that is is or isn't. Compression will not confirm other data that points to cam timing issues.

                As I stated earlier, it is not the actual compression that you are looking at to confirm valve timing issues, but the compression waveform itself. There are many examples of this in other forums, you can quickly do a search to see for yourself.

                As well, I don't how close you are to the Chicagoland area but trainers such as John Thornton have been putting on classes on these techniques for quite awhile now. Also, I've seen classes at Vision that also show these techniques. Bernie Thompson has also done classes all over the country on these very techniques.

                And no, I will state it again, a mechanical gauge will NOT be as effective as the compression waveform.

                No-Start.
                Last edited by No-Start; 07-22-2008, 03:40 PM.

                Comment

                • Nick
                  Senior Member
                  • Oct 2006
                  • 550

                  #23
                  I am not trying to say the tranducer doesn't work. I have used them in the past. Actually my use dates back to using a map sensor and engine vacuum. I found the time I spent, I could have gotten there faster with a gauge. Some engines a gauge may not be so easy. However I am speaking about my world.

                  You can go back and read my original post.

                  Obviously a waveform, showing compression over time is very accurate. IF you can properly read it.

                  I stated above a gauge is just as good, IMO. I have not been wrong when using a compression gauge or even a vaccum gauge when dealing with mechanical timing issues.


                  Please start a new thread. Share some of YOUR data. Not someone elses on some other site.

                  There are tons of great instructors teaching this technique. Some I know personally.

                  We can go back and forth all day, and night... In the long run I think you mistook my stand on the subject. Please reread the thread.

                  You made astatement that this test could not be done without a gauge, all I said it can be, and I do it.

                  I am not an egomaniac looking to prove something. I fix cars and thats it.
                  Mechanic-Instructor-Mobile Trouble Shooter

                  Autotechdiagnostics.com

                  Comment

                  • Cale
                    Member
                    • Apr 2008
                    • 43

                    #24
                    Originally posted by Nick
                    The pressure will show it. For example. late exhaust valve timing will cause a higher reading.

                    This has worked for me over the years with sohc v style engines and dohc v style engines.

                    Your arguement is that a pressure transducer will show the pressure but a gauge won't. They both read pressure. i am not arguing against the transducer, just stating it can all be done without it.

                    The time to learn how to properly and quickly read the waveforms from a tranducer was the subject of discussion.
                    Hi Nick,

                    I have to agree with No-start. On this particular Cavalier, both static and running compression tests were inconclusive. But the cylinder compression waveform nailed it:
                    Attached Files
                    Last edited by Cale; 07-22-2008, 08:01 PM. Reason: spelling

                    Comment

                    • No-Start
                      Senior Member
                      • Oct 2006
                      • 932

                      #25
                      Nice capture, Cale. It doesn't look like it was out much at all.

                      I hope you don't mind, but I put some cursors in your capture.
                      Attached Files

                      Comment

                      • No-Start
                        Senior Member
                        • Oct 2006
                        • 932

                        #26
                        Originally posted by Nick
                        Please start a new thread. Share some of YOUR data. Not someone elses on some other site.

                        There are tons of great instructors teaching this technique. Some I know personally.

                        We can go back and forth all day, and night... In the long run I think you mistook my stand on the subject. Please reread the thread.

                        You made astatement that this test could not be done without a gauge, all I said it can be, and I do it.
                        I have a fair bit of data to support my position but I'm not comfortable uploading it to the public side of this site. However, here is another example of where the transducer could work and the gauges won't. We can quickly see where the ignition is firing versus compression to verify some sort of timing issue.

                        I've read the thread already and don't see any point in re-reading it.

                        Originally posted by Nick
                        I am not an egomaniac looking to prove something. I fix cars and thats it.
                        Whoa! Don't know where that came from but looking at that statement, and the fact that you've private message me to state that I've derailed this thread, this will be the last reply I will be making.

                        No-Start.
                        Attached Files

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                        • aurora
                          Member
                          • Mar 2008
                          • 99

                          #27
                          Originally posted by No-Start
                          I have a fair bit of data to support my position but I'm not comfortable uploading it to the public side of this site.
                          No-Start.
                          I had not been a part of this thread but found this post intresting, with respect to the gauge in relation to the scope I would trust the scope more but it would be tricky also due to the computer controlling the spark for any given situation.
                          the only real way would be to have an identical car to be sure. it would be nice for Manu's to give us more scope specs in the future for these kinds of tests, it certanly would illiminate any doubt.

                          But I also found your post about uploading to the public forum dis-heartening, these threads are for us to support each other, I understand the time invested in diagnosing, lord knows I have invested to many hours to find the answers myself.

                          Regards
                          Tony

                          Comment

                          • SL_REPAIR
                            Member
                            • Mar 2008
                            • 62

                            #28
                            [QUOTE=aurora;6210]I had not been a part of this thread but found this post intresting, with respect to the gauge in relation to the scope I would trust the scope more but it would be tricky also due to the computer controlling the spark for any given situation.
                            the only real way would be to have an identical car to be sure. it would be nice for Manu's to give us more scope specs in the future for these kinds of tests, it certanly would illiminate any doubt.

                            But I also found your post about uploading to the public forum dis-heartening, these threads are for us to support each other, I understand the time invested in diagnosing, lord knows I have invested to many hours to find the answers myself.

                            Regards
                            Tony[/QUOTE
                            your right that is disheartening

                            Comment

                            • Steve6911
                              Moderator
                              • Feb 2007
                              • 2168

                              #29
                              Well if NO START does not feel comfortable uploading to this site for what ever his reason maybe someone else can start a new thread as Nick suggested. I myself do not have any high pressure transducers, only a low pressure which I use for fuel pressure readings. However I have been interested for some time now on the use of pressure transducers for different reasons and applications. Those of you who use them and have good and bad screen shots should post them if possible with cursors and explanations so we can all learn about it from this site. I do have the “First Look” sensor which I use fairly often with my Modis, maybe we can start a thread of second party applications as well.

                              Steve

                              Comment

                              • vasau
                                Senior Member
                                • Jul 2007
                                • 119

                                #30
                                I use only a 500psi transducer. I have a 100 psi one, but I found no use for it.
                                The 500 psi helps me well diagnosing exhaust blockage.
                                Here are the examples.
                                I don't see it usefull for timing diagnostics, but in some situations I do.
                                Attached Files
                                Last edited by vasau; 09-14-2008, 07:39 AM.

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