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2 cylinders not firing, this is getting to me..

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  • 2 cylinders not firing, this is getting to me..

    i dont know if i should be posting this here, but please give me some feedback.. the 2 rear cylinders on the drivers side are not firing. i put in a set of plugs.. all of the old ones were getting tired. this didnt change anything.. i swapped the plugs with ones from cylinders that were firing, this did nothing.. i put in a set of plug wires.. same shit.. i didnt expect this to change anything because if i pulled a plug wire off while the car was running i did have spark, but no combustion.. must be fuel, right? wrong... i have 12 volts at ALL injectors on the red wire, and i tested the green wire to ground while the car was running and all of them pulse.. all of the injectors click.. i have continuity from each injector ground wire all the way back to the computer (a while ago i re-wired the injectors from the recall nonsense) i pulled the drivers side fuel rail and verified that when the injectors click the pintle actually opens and fuel can pass throught (i blew into the inlet while clicking the injector).. so i have fuel, i have spark.. only thing left is compression.. i took the valve cover off since it was easy to get to and the rockers move like they should. im picking up a compression tester in a few hours... there are no sounds to indicate any internal engine problem.. this problem did not occur while doing anything crazy.. i started the car one afternoon, drove normally, and 5 minutes later this happened.. the injectors are DSM 450cc "blue tops" i bought them used, and had them cleaned and flow tested.. before i installed them i have about 2.8 ohms at each one of them.. now i have between 3 and 7 ohms on all of them.. i have 10 watt 6.8 ohm resistors at the ECU.. my plans for today are as follows... reassemble the rails with the injectors in different places and see if the misfire carries over to another cylinder... compression test all cylinders.. bypass the resistors at the computer... oh, i also used a different computer.. the misfire was still there. im also going to swap injecotor connectors and rule out any electrical.. which it cant be because the injectors all fire... anyway, im rambling, but im really stumpped.. please let me know if im missing something retarded. thanks

  • #2
    is it a steady misfire or erratic at all?

    unplug your idle controls, pcv, egr etc and see if it is still steady/erratic

    still doesn't preclude the injectors being physically plugged with debris but it is unlikely that only one side (especially driver's) would be affected

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    • #3
      did you try swaping the distributor ? bad crank angle sensor ?


      boost. does a body good!

      Comment


      • #4
        Ok so I am bringing up a topic from 2006 and all,

        What has been described here is EXACTLY the situation I am in just Now

        And I would really like to know what fixed the problem.

        Help much appreciated.
        85 Turbo Slick Top
        __________________________________________________ _____

        Comment


        • #5
          Check compression before you get to carried away, I had a bad pcv valve cause some wierd running condition, just pull the hose to the manifold and block of the pcv valve. Also check the inside of the cap and rotor for cracks, electric tracks.

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          • #6
            I also had crank sensor fail, I also checked the idems you checked. I had a extra dist, swapped it out and It ran good.

            http://www.cardomain.com/id/edsz31

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            • #7
              if the compression test doesn't lead anywhere, I would do exactly as you stated... change the injectors from the rear 2 to the front 2, and perhaps even get a used dist. to put in, or replace the CAS on your current one.

              Now, to me, it sounds like a problem that's close to what I'm having. It runs fine for 5 minutes. Turn the car off, and let it cool down over a period of a couple of hours (if you're not doing anything) and pay attention to the heat gauge.

              My car starts to reduce timing, or dump excess amounts of fuel or something, because as SOON as it gets to the operating temperature, it's a SLUG. it accelerates about half as much as it should, but there are no mechanical or heavy misfire sounds... maybe a light misfire or two.

              I think it has something to do with closed-loop operation. By the sounds of it, i think it's got to do with the computer, and not something mechanical.

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              • #8
                you can unplug the o-2 sensor to keep it from going in to closed loop. I used a 87t ecu so that I would not have to use the restistors.

                Comment


                • #9
                  edsz31 wrote: you can unplug the o-2 sensor to keep it from going in to closed loop. I used a 87t ecu so that I would not have to use the restistors.
                  I think it needs 2 of the 3 sensors to go into closed loop.

                  I unplugged my O2, and it still gets slow as soon as it hits operating temperature, so I'm not sure if just one sensor that needs to be disconnected.

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                  • #10
                    MY 85t Is a factory no emissions control no 02 sensor car as it was a specific model for New Zealand New Cars

                    I will put in the ECU from my 84T Auto parts car and if this does not work I think I will try and replace the CAS even though there is no code showing for it.

                    if this fails all 6 injectors will be sent out of cleaning and testing & perhaps a NEW cas from nissan
                    85 Turbo Slick Top
                    __________________________________________________ _____

                    Comment


                    • #11
                      james wrote: MY 85t Is a factory no emissions control no 02 sensor car as it was a specific model for New Zealand New Cars

                      I will put in the ECU from my 84T Auto parts car and if this does not work I think I will try and replace the CAS even though there is no code showing for it.

                      if this fails all 6 injectors will be sent out of cleaning and testing & perhaps a NEW cas from nissan
                      you can score a CAS from about 100 different cars that fit into the z31 distributor. I would much rather change the CAS 4 times then dish out like 200+ bucks once.

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                      • #12
                        Pathfinder/Maxima CAS are the same them ?

                        New Leads and Vacum Lines & PLugged Pop Off Valve didn't change anything

                        Neither did the other ECU I have

                        I guess the CAS must be bad, but there is no Error Code for it
                        85 Turbo Slick Top
                        __________________________________________________ _____

                        Comment


                        • #13
                          The car will not go into closed loop with the o2 sensor unplugged/missing.
                          "If your car cant do a burnout from a 60mph rolling start, then your engine needs more work."

                          "Nitrous doesn't blow up motors; Idiots with nitrous blow up motors."

                          Shooting for 500whp

                          Comment


                          • #14
                            85NA2T wrote: The car will not go into closed loop with the o2 sensor unplugged/missing.
                            this does not sound correct to me.

                            Isn't closed loop where its NOT reading the o2 sensor

                            Open loop is where it is reading the o2 sensor ?

                            this is all irrelevant as my car has no o2 and I can guarantee it is like this from factory, just like it came with no EGR or catalytic converter.
                            85 Turbo Slick Top
                            __________________________________________________ _____

                            Comment


                            • #15
                              [quote]james wrote:
                              Originally posted by 85NA2T
                              The car will not go into closed loop with the o2 sensor unplugged/missing.
                              this does not sound correct to me.

                              Isn't closed loop where its NOT reading the o2 sensor

                              Open loop is where it is reading the o2 sensor ?

                              this is all irrelevant as my car has no o2 and I can guarantee it is like this from factory, just like it came with no EGR or catalytic converter.
                              EU models came with a block-off plate for EGR. that's how I managed to buy one for like 6 bucks from Nissan.

                              O2 sensor plugged used to make my car buck and hesitate very violently even from as soon as i would start it up, so I'm not sure.

                              The last post in this thread: viewtopic.php?f=15&t=5340 has a listing of different vehicles that use the same CAS. I can send you one if you like as well. just pay 25, shipping included, and it's yours.

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