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Problems with the 3.4 TURBO-again

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  • #31
    you can really hear it when i take off from around the turn


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    • #32
      If I am only getting 12-20 psi of oil at the turbo around 3-4g would that maybe be making the turbo to choke? I put a very small restrictor on the turbo line and I only get 12 psi at idle and aroun 15 at 2500


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      • #33
        I changed out the oil line going to the turbo and still have the same problem.


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        • #34
          Do you think that it can be the spark plugs needing to be gaped?


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          • #35
            What troubleshooting have you done so far and other the FMU what parts have you eliminated?

            Is it throwing any codes? Are there any other driveability issues?

            Mine did the same sort of lunging after a car wash. The air filter would get soaked with water and it seemed to kill the accuracy of the MAF sensor- to the point that the car would barely run until it dried off. When it got a clean signal, it would surge forward. A corrupted signal and it would virtually stop in it's tracks. I now have a full fender well which has prevented it.

            Tim
            1995 Z34 - T04E "60" trim, 42.5 lb/hr injectors, AEM WBO2, FFP UD&DB, 3" exhaust, 2800 stall, shift kit, tranny cooler, Powerslot, Hawk HPS, rear disc conversion, KYB, Eibach, HMS F&R STB, Fittipaldi Force 18" wheels, big stereo, lots more coming eventually...
            325 whp 350 lb-ft

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            • #36
              Well I fixed the boost leaks and still doing its thing. I am replacing the plugs and well see if that fixes it.
              Last edited by d.o.h.c; 11-02-2007, 03:55 PM.


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              • #37
                Well if you just changed the spring in the gate then it will stand to reason it may not be seated properly within its housing...(although it is really hard to screw that up in a tial, nevertheless).To eliminate the w/g (my post snipped from another string);
                * Make sure the "right" spring rate is in the W/G indeed...
                if you are sure then, take the compressor vac line (vacuum line coming out of compressor) and place on top of w/g Remove the vac line at the bottom, in other words it is opened to the atmosphere. Drive the car on an open road with a slow throttle ramp, if you cannot build boost over 3psi, then the w/g maybe culprit assuming you have eliminated an exhaust leak...(NB: the point here is that you want to pressurize the top part of the w/g with boost + w/g spring p, ultimately if the unit is working properly the valve should never be able to *open).
                Another NB: Make sure you get on the throttle ever so slightly because you can overspeed the turbine very quickly here for that an open road is very essential it is easier to modulate your speed.

                If that turns out to be a non-issue, then I will start diagnosing the turbo...restrictors IMO are meant for non-journal turbos, (restriction can be done simply with the oil-lines; it will suck if you made the shaft anemic for oil.
                Last edited by nocutt; 11-03-2007, 01:59 PM.
                3800 S3 intercooled turbo...

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                • #38
                  what ratio is your fmu?

                  What turbo are you running?

                  what air fuel ratio are you at at wot and trying to go past 3 psi of boost?

                  What size injectors are you running?

                  Sounds to me like you are runing really lean or really really rich once you see more boost and your FMU is making the injectors dump fuel big time

                  I would ditch the fmu myself, and get a chip burned.

                  I have a turbo setup as well, 7 psi tial wastegate and spring, sc61 turbo with a custom chip and a safc to tuen fuel on 24 lb injeectors(3.4 pr not DOHC) Never had the problem taht you are describing.

                  I am however running a map setup whereas you are maf.

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                  • #39
                    It was the FMU.


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                    • #40
                      what was wrong with it? it sounded like the same thing as you originally had so i knew it had to be something in your fuel delivery.

                      S
                      Shane "RedZMonte"
                      2004 Corvette Z06 Commemorative Edition -VIRGIN
                      1995 Monte Carlo Z34 14.38@101mph, 331hp/355tq
                      -Turbonetics T04E Super 60 Turbo, 2.5" Borla Catback, OBDII, 42.5# Injectors
                      2004 Subaru WRX STI -Lightly Modded (SOLD)
                      1994 Lumina Z34 -VIRGIN (SOLD)
                      1992 Lumina Z34-VIRGIN (RIP)
                      1992 L67 Lumina Z34 (SOLD)
                      1990 Turbo Grand Prix (SOLD)

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                      • #41
                        Originally posted by d.o.h.c View Post
                        It was the FMU.
                        Figured.
                        Lifting my front wheels, one jack at a time.

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                        • #42
                          Its wierd as fuck man, I had the fmu with the 3 psi spring and it worked perfect. I had it hooked up with the 7 psi spring and it was not working past 3 psi. It was putting way to much fuel in. SO i disconnected it and it works perfect. The a/f gauge reads green/ yellow with no fmu at 5 psi. So I have no idea. I did replace the FPR though.
                          Last edited by d.o.h.c; 11-04-2007, 01:35 AM.


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                          • #43
                            Hey guyes, I am still having a problem with starting the car. It cranks good, just takes 10-13 seconds of cranking to get it to start and once it starts it puffs a little smoke and smells bad of raw gas


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                            • #44
                              Over fueling maybe? Do a injector leak down test since everything else seem to have checked out good before?? ... Also did you ever do a fuel pressure test? If not, What's stopping you? One lean condition under boost could cost you a engine!
                              Lifting my front wheels, one jack at a time.

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                              • #45
                                i did check the fuel pressure, a steady 40lbs when primed. I always watch my a/f gauge when under boost, if its not green I stop. You think that it could just need a tune?


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