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Taking ideas, problems with KA-T.

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  • Taking ideas, problems with KA-T.

    I am having problems with my engine, long story short, I blew my motor a few years ago and have just recently gotten it back up and running. It is a fully built KA-T, PeakBoost Mani, T3/T04E 57 trim, stock intake mani, stock S13 cams, 550s, Enthalpy ROM Tune, external coil conversion with MSD Blaster SS. Pretty much every part has been changed, new block, head, turbo, plumbing, injectors, etc.

    Compression on warm motor checks good, plug gap .028, fuel pressure 50psi. It does have a MAJOR boost leak near the back of the intake manifold or around cyl 3 or 4 that for the life of me I cannot find. I have removed most of the emissions, EGR block off is installed, leak sounds like it is coming from near IACV, but I cannot see bubbles when spraying water. Could this be valves? How do I track this down, I am looking for someone local with a smoke machine.

    Well it starts fine, idles well and drives pretty good, A/F is around 13:1 at idle, <12:1 under boost, and maybe 16:1 when lifted. But it dies like crazy when lifting off and coming to a stop. It has also started to misfire like mad, right at 3500 RPM.

    When it dies, un-plugging the injectors will allow it to start up, strange. I did speak with Martin at Enthalpy and will be sending a second ECU, he said this one got very hot on his test bench. I am not currently recirculated, but he said that he worries more about my MAF location, you be the judge (pic at end of post).

    Do you think the Blaster SS is causing the misfires?

    I have pulled codes and it keeps throwing the knock sensor and coolant sensor, I have rewired the CTS plug and tested and tried two different sensors, one used one new. The knock sensor should not affect much I dont think.

    I am just looking for input, it is so tough to track stuff down sometimes when you have changed everything. Things are easy when you add or swap one part and it runs goofy.


  • #2
    The fact that you have to disconnect the injectors to restart leads me to think that one or more injectors is leaking...however since you have top feeds I am not sure how that is possible. I had similar issues with idling and missfiring when i tore a side-feed injector o-ring. I guess you could try pulling the plugs on the injectors one at a time and listen for the engine to change note. The one where it does not change is leaking fuel into the engine.

    The maf location looks ok, mine is in a similar location.

    The knock sensor could put you in the knock maps which will have fairly retarded timing, I don't think that will effect the misfiring you are experiencing.

    Try to fix the boost leak, my guess is that it is manifold to head or upper to lower manifold connection. Royal pain in the arse to fix but it needs to be done. Otherise maybe you have a hole in one of the vacuum lines.

    I had some wierd idle fluctuation ssues until I loosened the diverter valve spring to be able to open at idle. After that my idle has been rock solid.
    ::edit, duh your not recirculated so there will definitely be some stalling issues as the engine goes rich when the metered air gets blown out. I am not sure how to fix that with a rom tune without recirculating. That could be your stalling problem. /edit::

    PS: Holy an fittings batman.
    Last edited by LigouriRd; 09-09-2010, 02:08 PM. Reason: I am a dumbass. read non-recirculated as recirculated.
    "To an engineer, the glass is neither half empty nor half full. It is twice as big as it needs to be."
    '96 Nissan 240SX KA-T
    '05 Grand Cherokee

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    • #3
      FWIW I always had issues with topfeeds leaking on my SR

      My money is on the injectors for the boost leak as well
      Last edited by veilside180sx; 09-09-2010, 01:19 PM.
      Between rides...unless you count a WD21...

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      • #4
        I see the problem.

        that engine bay is too pretty. throw oil and road grime in there and the car will run like stink.


        Umm, a CTS problem will cause all kinds of weird driveability problems. If it's throwing codes for that, I'd look further into it. it could be a damaged wire between the sensor and harness that's making an intermittent connection..

        Just throwing out guesses really, but that's definitely something that will cause drieability issues.
        Originally posted by SoSideways
        I don't care what color they are as long as they are LONG AND HARD.
        '04 G35 Sedan 6MT- The DD
        '96 240SX- The Track Toy

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        • #5
          non recirc BOV???

          that causes issues on closed throttle right?
          I am SKULLWORKS

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          • #6
            Get a cigarette and get lots of smoke going, might be able to see the flow around the leak at idle... maybe.


            My bets are on a slight boost leak. Check around the injectors, seen that happen a few times with improperly held injectors.
            '18 Chevrolet Volt - Electric fun hatch for DD duty!


            DefSport Koni Sleeve and Spring Perch Buy!!!
            http://www.nissanroadracing.com/showthread.php?t=5902

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            • #7
              Blowing cig smoke into my intake manifold once helped me learn how all our vac lines were routed, and how I'd not connected all of them. Can work surprisingly well if you don't have an air compressor to find where your boost / vac leaks are hiding.
              '95 240sx

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              • #8
                I put two cigs worth of smoke in in an attempt to find it and saw nothing. I do have a compressor and have tried to pressurize the system, with 60 psi in the line I can maybe get 4psi to build, but it will not hold at all. I will check injector leaking and see about that. Le sigh, I think my plan of attack is going to be this....figure out the coolant temp sensor, get a smoke machine and track the leak, work from there, if the miss is still happening convert back to internal coil for now. And add recirc.
                Last edited by Colorado S14; 09-10-2010, 06:23 AM.

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