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Disconnect EGR valve?

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  • Disconnect EGR valve?

    I have a 86 NA. What are the concequences if I remove and block off the EGR valve? If I run vacumn to it, it runs smooth, then like a switch, starts running crappy. If I turn the car off and restart it, it runs smooth till under load, then crappy again. Runs great with the vacumn plugged, but gas milage drops noticiably. I have so many questions, but this is a good place to start. Thanks guys.

  • #2
    well, as soon as you go to get your next emmisions done then you will fail if it is gone. But if you remove it you will not hurt anything. Its there for emmisions only.
    85 Z31 6.0 LSX turbo 766whp/792wtq
    04 GTO, LS6, big cam, porting, N20... underway for summertime daily driver.


    • #3
      If bypassing it isn't of a concern to you, then simply unbolt it and slip the EGR tube out of the upper plenum. Pop a nickel in between the gaskets and center it to sit there like the tube did, re-assemble.(You're now blocked off, but have the appearance everything is as it was originally)

      If keeping the EGR functional is of a concern, verify what is at fault.
      EGR valves tend to get sticky over time, Disassemble and thoroughly soak with PB BLaster, work it free and re-assemble.
      Another culprit could be the EGR Vacuum Control Solonoid. To validate that this is the issue, when the probelm occurs, unplug the electrical connector leading to the Vacuum Solonoid and if the issue goes away...replace the solonoid with a known working one.

      I am skipping over the obvious, vacuum is not leaking from old, loose, or hardened vacuum lines.
      I am here to help...


      • #4
        reinventing the wheel

        Im like a new born baby with its eyes opened. Im really blessed to find this forum. Thank you guys. Im so used to reinventing the dang Z wheel.
        Attached Files


        • #5

          you just won't have as much carbon build-up


          • #6
            we do not have emission checks here in Florida, so I can do without the EGR. Does it in anyway make the ECU richen the Fuel. Seems since I bi-passed the EGR it has become very thirsty. Tail pipe seems more black. I do not have a broadband o2 sensor yet.


            • #7
              I have always suspected that removing it would infact richen the mixture some. I have everything removed from my 86' but I'm deliberately running rich right now so it's not a real good comparison but I would think that your mixture would be richend some post EGR removal.


              • #8
                Thanks, that is what I suspect. That it will run rich. I wonder what it does to the combustion temp. All this stuff seems so closley related.


                • #9
                  With the EGR removed it should run a leaner mixture. More air is getting into the cylinder, because its not being displaced by exhaust. The only reason it would run richer is if your o2 sensor is seeing the lean mix and compensating by adding more fuel. However it shouldnt be so rich that you notice black soot building up on the rear bumper cover.

                  Richer mixture - Lower combustion chamber temperatures.
                  Leaner Mixture - Higher combustion chamber temperatures.

                  A 14.7:1 af mixture will burn roughly 2500 degrees F. This is where your Nox Emissions occure.
                  ""You gota watch out in this weather. Its when them white boys with their turbos come out to play" Mr. Rimpson - UTI Instructor, refering to a slightly damp 50 degree day.


                  • #10
                    with the vacumn line running to the EGR blocked off, it runs smoothly. Connected, it runs smooth after just starting it up, and after about a block of driving, it starts idleing like crap. I know its not right. My exhaust went from grey to dark black and feul comsumption has halved.


                    • #11
                      Pull the vacuum line off of it, and get a long one.

                      With the engine idling, plug the long one onto it, and suck on it with your mouth. It SHOULD start making the engine die, if it doesn't, pull on it as hard as you can.. you'll hear it "POP" and the engine will usually stall from that one.

                      Idle it again, and exercise it a bunch of times, until you're sure that it's not sticking anymore.

                      I've gotten a few Z's through emissions like this. I usually have the guys leave it on the rollers while I do this right after a fail, then they'll retest and it'll pass. Most of them are like "WTF".. lol

                      Sounds like everythings working fine, it's just sticking open.. exercise it a bit... it'll probably break enough crud off of it to work properly again.
                      vg33et -blew some chunks outta it, then gave it all away.
                      2009 370z touring/nav/sports


                      • #12
                        thanks, your becoming my favorite Ga. Cracker


                        • #13
                          Your engine will probably run cleaner hah

                          I made this manifold a couple of months ago. I took it off yesterday to do my injectors and it was just fricken gross.

                          Stupid egr and my rich running engine.


                          • #14
                            hey chronic, how is that manifold holding up to boost?
                            Lance 'never-ending 88na2t project' Landry
                            I sell Z stuff when I'm not being lazy.
                            Trace cell phones via GPS:


                            • #15
                              washers under plenum bolts

                              AAAAAAAAAAAAHHHHHH! I see something. The washers under your plenum bolts. Where did you get these? Did you fabricate them? I did not have them or use them when I installed(unsucessfully) my gutted plenum, ended up breaking seat on lower manifold bolt, causing a can of worms. I think I see what could have been my problem.