Like Socrates on the pot this morning it came to me

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  • Witsend
    Banned
    • Nov 2012
    • 2942

    Like Socrates on the pot this morning it came to me

    Like a body, an engine isn't going to want to take anything in if it can't get everything out too.
    I'm really surprised no one sells a simple pair of heavy duty thread in steel whistles that you just screw into the two upper o2 sensor holes That will really let someone know if they got a side that's corked up.
  • Wheel
    Senior Member
    • Jul 2007
    • 719

    #2
    Originally posted by Witsend
    Like a body, an engine isn't going to want to take anything in if it can't get everything out too.
    I'm really surprised no one sells a simple pair of heavy duty thread in steel whistles that you just screw into the two upper o2 sensor holes That will really let someone know if they got a side that's corked up.
    Vacuum gauge or scan tool much easier and no wrenches required.
    You can expect the reputation of your business to be no better than the cheapest item or service you are willing to sell. - Wheel

    Comment

    • Witsend
      Banned
      • Nov 2012
      • 2942

      #3
      Some times it's just bank one or bank two upstream cat and if you have both upstream o2 sensors removed , one side that is clogged is going to jet out at a much higher pressure than the other . Screw in the equivalent of a pair of $10 variable pitch miniature steam locomotive whistles, same size as a o2 sensor that is rugged enough not to warp or melt with hot restricted exhaust blowing at through it at 120 decibels for a few minutes straight and folk like me would have a pair just for the fun of it.

      Comment

      • Joe Rappa
        Snap-on DSD
        • Aug 2007
        • 2050

        #4
        Originally posted by Witsend
        Some times it's just bank one or bank two upstream cat and if you have both upstream o2 sensors removed , one side that is clogged is going to jet out at a much higher pressure than the other . Screw in the equivalent of a pair of $10 variable pitch miniature steam locomotive whistles, same size as a o2 sensor that is rugged enough not to warp or melt with hot restricted exhaust blowing at through it at 120 decibels for a few minutes straight and folk like me would have a pair just for the fun of it.
        I think you just found yourself a side business. Best of luck! I hope you make a Million.

        Joe
        "You don't build a reputation on what you're going to do"
        Henry Ford

        Comment

        • diesel71
          Senior Member
          • Feb 2008
          • 921

          #5
          LOL....... ,the whistle would work but I think that's what they make scanners for.

          Comment

          • Wheel
            Senior Member
            • Jul 2007
            • 719

            #6
            Originally posted by diesel71
            LOL....... ,the whistle would work but I think that's what they make scanners for.
            exactly - rpm, map, o2, and fuel trim pids come to mind.
            That sucker would already be on its way to the muffler shop
            in less time than it would take to even open the hood and FIND the sensors on some cars. Time = $$$ flatrate or no.
            Also, the scan tool will help you determine what caused the converter's downfall
            so the new one won't experience a premature death.
            You can expect the reputation of your business to be no better than the cheapest item or service you are willing to sell. - Wheel

            Comment

            • Witsend
              Banned
              • Nov 2012
              • 2942

              #7
              LOL, So I if only one bank upstream cat is restricted causing a performance issue you are going to sell me or sublet my car to a muffler shop, replacement of all 3 of my car's cats for $1500 based on a low Map sensor / vacuum guage, high DPFE V reading and higher fuel trims on one side, is that correct? Maybe by high misfire counts on one bank , or if you did a relative compression check with high amp probe you could see a difference side to side if corked enough, but many shops will ask for more diag time if they don't have a cat efficiency code and want to uncork what is corked or physically verify if it involves one or both banks. (might want to pull a downstream o2 sensors to see if it's corked further donwstream )I would want to have at least the upstream O2s removed or at least freed up before I turned it over to my local Mexican Muffler shop to have a new Cat welded in, because if they dont free up right , you'll need a directfit assembly instead. Time well spent I feel. Kinda would suck if everyone was wrong and the Mexican Muffler shop just found an a 8 ball shoved up one of the dual exhausts and inside the muffler.
              Last edited by Witsend; 07-01-2014, 04:49 PM.

              Comment

              • David Green
                Senior Member
                • Oct 2009
                • 382

                #8
                What happens if you plug your two whistles into the upstream exhaust lambda ports and they blow different tunes , is that then a compression variation problem, a leak somewhere or a pressure differential problem from the internal engine

                Over here we have attachments that connect directly into the exhaust lambda ports and I have a diagnostic machine that measures pressure and gas flow rates, so a comparison of each bank pressure and gas flow rate can be carried out, if a suspected fault is present.

                The idea then is to already have checked good known systems to have a bench mark reading to compare your findings to. Over here on four cylinder engines we say a back pressure around 3 to 4 PSI is normal, so anything significantly different to this would indicate a problem

                Comment

                • Crusty
                  Senior Member
                  • Dec 2007
                  • 2450

                  #9
                  Originally posted by David Green
                  What happens if you plug your two whistles into the upstream exhaust lambda ports and they blow different tunes , is that then a compression variation problem, a leak somewhere or a pressure differential problem from the internal engine

                  Over here we have attachments that connect directly into the exhaust lambda ports and I have a diagnostic machine that measures pressure and gas flow rates, so a comparison of each bank pressure and gas flow rate can be carried out, if a suspected fault is present.

                  The idea then is to already have checked good known systems to have a bench mark reading to compare your findings to. Over here on four cylinder engines we say a back pressure around 3 to 4 PSI is normal, so anything significantly different to this would indicate a problem
                  From what I've read, a normal exhaust backpressure PSI is 1.5 to 2.0 @-2000-RPM
                  3 or 4 PSI here would indicate a restricted exhaust.

                  Maybe that's because you guys stuff soft coal through the engines in Europe-??

                  Comment

                  • Witsend
                    Banned
                    • Nov 2012
                    • 2942

                    #10
                    I'm not going to split hairs over a couple psi and which whistle blows louder , they could just be a cheap Go -No go kind of thing for a typical lowly passenger car that you wouldn't hear a peep out of them unless you would be seeing double the back pressure Jonnie Go Fast would want to see on his Sleeper with the Flow Masters that an angry neighbor shoved an 8 ball into one of his mufflers. If all 3 0r 4 are whisling Dixie , then what's behind them would be getting detached and rechecked
                    If you got both upstream O2s removed before you thread in the WhistleThingys and start up breifly and find the engine vacuum hasn't increased with better throttle response , and engine is still missing , the upstream o2s removed , exhaust should at least be uncorked enough to do a cranking compression test with a high amp probe to single out the cylinder lacking compression. Naturally you won't want to put a new cat on some car, and not deal with a dead miss, overfueling condition , vacuum leaks or poor state of tune.( Especially when Whistling Dixie.

                    Comment

                    • liljoe
                      Member
                      • Nov 2014
                      • 73

                      #11
                      I have a metal adapter that screws into the o2 hole and has a nipple that you hook up your old fashioned fuel pressure gauge to, instant verification right there.....

                      Kind of related, kind of not, but I had a 76 Camero with 400 Pontiac engine with nice cam and intake combo with ported heads and I could check at the pipe right after the headers and had 2.4 psi at 2000 rpm no load, I could check under the same conditions but at the egr port and it was 8.6 psi. I was very amazed at how much exhaust back pressure was built up in the engine before it even got to the header. It had 2.5 inch exhaust with flow muffins on it and under WOT @ 5500 rpm it was as high as 6.5 psi at the pipe and 11.6 at the egr port. This car had no issues, was just messing around trying to get known good readings when I first got my adapter. Tried everything to get a lower number but it never happened....

                      Comment

                      • Witsend
                        Banned
                        • Nov 2012
                        • 2942

                        #12
                        I always thought some back presure was desirable for low and mid range torque , smoother idle and throttle response, longer exhaust valve life expectancy, EGR system operation (so you can run 87 instead of 91 octane)without ping, early fuel evaporation valve operation (exhaust Flapper thingy to warm intake manifolds and open choke before car was driveable in cold weather.

                        Comment

                        • Crusty
                          Senior Member
                          • Dec 2007
                          • 2450

                          #13
                          Originally posted by Witsend
                          I always thought some back presure was desirable for low and mid range torque , smoother idle and throttle response, longer exhaust valve life expectancy, EGR system operation (so you can run 87 instead of 91 octane)without ping, early fuel evaporation valve operation (exhaust Flapper thingy to warm intake manifolds and open choke before car was driveable in cold weather.
                          That was called a "heat riser" which had a bimetallic coil to keep it closed until it warmed up.
                          The intent was to redirect the exhaust gasses back through a port in the intake manifold that ran underneath the plenum chamber and out the opposite side exhaust of the Y-pipe, to warm the plenum chamber which helped with proper fuel vaporization during cold engine operation.
                          Flapper thingy is kinda like the Kaphoophoo valve-!!! LOL
                          Many early emissions components were called kaphoophoo valves....LOL

                          Air in and out needs to be balanced, controlled, matched and timed in order to get the best combination of engine "breathing".

                          Air needs to be thought of as a very thin liquid and people need to keep in mind that even though it is very thin and light, it does in fact have a mass and weight and a momentum. It doesn't just start and stop as the valves are opening and closing.

                          One example is headers.....too much ease of mass momentum can cause cylinder scavenging at an improper time depending on how the cam is machined for rise, lift, slope and duration.

                          It is less a matter of "backpressure" as it is "matching" the mass and weight of INFLOWING mass and weight.

                          That's my story and I'm sticking to it....LOL

                          Comment

                          • Crusty
                            Senior Member
                            • Dec 2007
                            • 2450

                            #14
                            [QUOTE=liljoe;45228]I have a metal adapter that screws into the o2 hole and has a nipple that you hook up your old fashioned fuel pressure gauge to, instant verification right there.....

                            I guess I'm a bit of a "bottom feeder" like Witsend, because I made a few adaptors to check exhaust backpressure by simply knocking the guts out of an old oxygen sensor and using some JB-Weld attaching a piece of steel tubing about 2 or 3 inches long onto which I can hook the rubber hose of my ancient Fuel pressure, vacuum, compound guage back in the 1980's.

                            There ARE SPECIFICATIONS for this and they are published in service manuals but are not necessarily obvious to find.

                            One place to look are GM "A" and "C" charts of the late 80's for starters.

                            The more things change, the more they stay the same......

                            Again (LOL) That's my story and I'm sticking to it.....LOL

                            As soon as you have a "modified" engine, the factory original specs and values will change. Whether that is for better or worse is subjective.

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