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    Mazda gtr emission test fail

    Some months ago i bought myself a MAzda 323 gtx with a gtr swap (engine,transmission,ecu,maf and some 515cc injectors). I've used alot of time to get it road legal, and now its just one thing left to fix: the emission test.

    I've had it on a emission test, and the result was a CO on 7.4. I immediately tought it was the big injectors, so i bought four rx7 460cc high impedance injectors (since im running gtx wiring i can't use gtr injectors).

    The problem is that the car is still running way rich. I've checked for fault codes, and it only has one; (35) solenoid valve (pressure regulator control, high temp).
    Since my car doesn't have the original fuel pressure regulator, both the solenoid valves are disconnected. This fault code shouldn't do anything with the emissions?

    I've checked the temp sensor and the fuel pressure. Nothing wrong.

    to check the values myself i connected a wideband in the exhaust. It has a narrowband output, so i connected that one to the car so i can be sure it gets a correct lambda-value.

    The weird thing is that its not always running rich. Sometimes under warmup its running lean, before it suddenly starts running rich again. sometimes it also runs on 14.7, but suddenly does a jump in rpm, and then running way rich.

    Does anyone has any ideas what can cause this? im starting to get out of ideas..

    #2
    This list of things that could be wrong is comically vast. There just isnt enough info here to remotely diagnose. The fault code could be all off the problem. If the ECU thinks there is an FPR problem, it could be dumping fuel to keep a lean melt from happening. Cuz it sure doesn't know that you've done those mods. Or it could be a million other things. The random AFR changes you describe point, maybe, to a bad TPS. This was one symptom that my car did with that problem, but the main symptom was total engine shutdown at random intervals which you don't have. But TPS diagnosis is easy enough, so you can do that and rule it out and move on. Bad 02 sensor or bad wiring between it and ecu? A leak, even a tiny one, anywhere in the intake tract? Stuck injector? Mismatched injector ballast? Clogged cat? Gad.
    Last edited by jay; 01-21-2018, 12:28 PM.
    '90 AWD Protege, full GTR drivetrain swap, ~320 whp daily driver, RIP, and
    '90 AWD Protege, yet another GTR swap, Open class rallycar with a Toyota GT4 gearbox swap, thus crossing the line between hobby and mental illness. And a Brabus E55 K8, removing all doubt.
    http://www.wihandyman.com/forum/vbpi...?do=view&g=110
    http://www.cardomain.com/ride/2599486

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      #3
      After alot of troubleshooting i've still not been able to locate the issue.


      I've checked:
      Lambda signal
      Temperature sensor
      Tps sensor
      Swithed all igniton parts except for coil
      Fuel pressure
      Compression
      Fuel filter
      Fitted original gt-r injectors and fitted gt-r injector resistor pack
      Looked for air leaks, can't seem to find any

      The car is now running lean almost all the time, except when i have full throttle and boost. However, some times when it's idling, it suddenly starts to run rich. It is also running rich when its cold, but i assume that is correct.

      The idle is quite high when cold. Drops when it gets hot, but i stil think it's a little bit high (1200 rpm or so).

      Does anyone has any more good ideas of what i can try? i have got rid of the fault code regarding solenoid valve for the pressure regulator, but i've got a new one, for the purge control valve. im struggling to locate it in my engine bay. Where should it be located? could it mess with the emissions?

      Also, to eliminate air leak, i wondered if i should change the intake manifold gasket. Does anyone know where i can buy it? Can't find any on ebay..

      Comment


        #4
        have you pinpointed the airleak to the intake manifold gasket??
        what part of the test are you failing now/still? by how much?
        ---Has ClubProtege helped you in someway? show your support by Contributing--- Click Here---

        1992- project FE3..... 313 WHP @ 9.3psi




        I pet my dash when I get into the car..."good car"
        he actually has a mazda tree, parts grow on it

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          #5
          no, but the idea was to change it to be certain the car has no air leaks.

          Technically the car will probably go trough emission test now, since it is running to lean, but i can't use it when it's running so lean..

          I have mounted a wideband in the car so i can read the lambda value. It is on about 16.5 on idle, and drops down to 12 once in a while.

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            #6
            who cares about being too lean at idle. whats important is the figure under boost. these VAF systems are notorious for being unstable in either idle conditions or boost. pick your happy place & live with it or maybe go to aftermarket
            ---Has ClubProtege helped you in someway? show your support by Contributing--- Click Here---

            1992- project FE3..... 313 WHP @ 9.3psi




            I pet my dash when I get into the car..."good car"
            he actually has a mazda tree, parts grow on it

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              #7
              That may be, but i also notice a powerloss in the bottom register. It's clearly running way to lean before the turbo kicks in. I dont think it's supposed to be like that.

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