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  • Overboosting


    I have one serious problem with my 90.

    I have a 1KD-FTV engine and automatic
    When it is cold, it seems the normal. Turbo pressure of about 1,2bar. When it gets hot, the 1,4-1,7bar. Then engine light, and the engine running at maximum 1200 rpm.

    I have searched and read a lot on the forums, but still failed to locate the fault on my car.

    I have tried the following:

    Replaced Turbo incl step motor
    Tested with different VSV and other MAP sensor
    Cleaned EGR
    Forced EGR to be both open and closed
    Replaced SVC
    Checked all cables and connectors
    Checked vacuum

    Everything seems to be ok. I can not understand what the problem is.

    It happens around 2000 - 2500 rpm, especially overtaking and when I have a trailer, and up hills.

    After that I have understood you have two chambers in the EGR cooler, but I have only one.

    Is there anyone who has been involved in the same issue, and can explain to me what is wrong?

    PS: I have used google translate so my English is a bit poor. Sorry.

  • #2
    I might also mention that I think the ticking much more in the rail when in overboost mode.
    When it is ok, it is more quiet.


    • #3
      I have also tried a different ECU. And it has been at an Toyota garage, but they couldn't tell me anything.


      • #4
        Different engine to what we have over here in Australis in this model.
        We only have the 1KZ, and they only run 10psi of boost.
        No vacuum leaks to wastegate actuator?

        Regards, Jason.


        • #5
          Ok. Maybe i should have asked in 120 section?
          We had 90's with this engine in 2001 and 2002.
          It has variable vanes, som there is no wastegate


          • #6
            Double post??
            Last edited by SWR; 18-02-2015, 12:10 AM.


            • #7
              Gday Muzaki

              Originally posted by Muzaki View Post
              When it is cold, it seems the normal. Turbo pressure of about 1,2bar.
              1bar = 14.5psi
              2bar = 29 psi??? Eeeek! ... Not good!

              It is supposed to be around 14psi max boost (1bar) so i can only imagine that your EGR port (At the cylinder head) is blocked off/ Restricted!!.. because the engine "CAN NOT" absorb the access turbo boost and would be stalling your turbo!... This is not a good thing!.. And it will also impact on your fuel pressures if Not a chip fitted.... would be worse if chip is fitted!

              Your EGR heat exchange would look more of a round looking thing with two coolant hoses attached to it and it does not have a quick return chamber for the turbo boost dump like on our later euro4 models here in oz!

              NOTE: The EGR valve on the 1KD's "IS" also used as the turbo waste gate to dump access boost back into the exhaust.

              REASON! when you DE-celerate the exhaust manifold pressure is lower than the intake manifold pressure and access turbo boost can be dumped back into the exhaust without stalling the turbo.

              TIP: Remove EGR heat exchange from the cylinder head and see if there has been a restricting plate fitted? .. If plate has been fitted then bin it as it "WILL NOT" serve you any good at all.

              Your engine is equipped with an ECU (Electronic Control Unit) which communicates in real time to the engines numerous sensors so even if you was to "TRY" to fool the MAP sensor (Manifold Absolute Pressure) this will be contradicted by the MAF sensor (Mass Air Flow) as this measures Air flow/ Air temp & Atmospheric pressure which is altitude!

              Block OR restrict the EGR flow (1KD not 1KZ) and it "WILL" cause global up-set with the ECU's pri-programmed call-up-maps!!!


              Originally posted by Muzaki View Post
              It happens around 2000 - 2500 rpm, especially overtaking and when I have a trailer, and up hills.
              Perfect cruise for max turbo boost is cruise/Mid range Which is approx between 2,000rpm and 2,500rpm plus when overtaking and climbing hills!

              Sounds like your engine is not able to dump access boost?

              For those who are not aware of the 1KD 90 series?
              Last edited by SWR; 18-02-2015, 12:12 AM.


              • #8
                Thanx for the reply.

                I have opened the heat exchanger, and it is fully open. There is no plate blocking the EGR.

                When i drive and everything is normal, the boost is slowly rising from 0 ->0,5 then fast from 0,5 -> 1,2. When i release the throttle it drops fast. like its being dumped trough the EGR as it should.

                When its not normal, it still slow from 0 -> 0,5 then fast from 0,5 -> 1,5 (1,7). If i release the throttle it still dumps trough the EGR.

                I have tried to bypass the vacuum valve under the intake to make sure the EGR is open, just to se if that makes any difference.

                When its normal i can observe the arm that is adjusting the vanes is moving all the way up when im building boost. When its not normal the arm goes half way up, then when its overboosting it jumps all the way up like there is something suddenly telling the step motor to close the vanes.

                Can anyone explain how the boost is adjusted. Step by step, so that I can trace it and maybe find the defect.
                I tough maybe it was the MAP sensor that gave the order to close the vanes and drop pressure, but it seems like there is more complicated since there are a VSV before the MAP, and there are two valves controlling the EGR.

                If someone could explain it like this:
                When A senses X bar, it tells B to do do following, and the C does another thing, witch then moved D
                Then maybe I can finally understand why its having to much pressure.

                I have been dealing with this problem for about 6 months I think I have tried anything, but apparently I haven't sins the problem is still there.

                I got at tip today that maybe it could be defective or dirty MAF, og cracked Intercooler??

                Another question. The lower valve, between EGR and Vacuum pump, will that regulate vacuum, or just open and close.
                Before that valve i got -0,8bar, but after i got -0,2 -> -0,5


                • #9
                  Gday Muzaki

                  Originally posted by Muzaki View Post
                  I have opened the heat exchanger, and it is fully open. There is no plate blocking the EGR.
                  I think you are looking at wrong part of engine??

                  The part you are explaining is the actual EGR valve that sits at the back of engine where turbo inter-cooler connects?

                  The actual heat exchange bolts on directly to the cylinder head at front of engine behind the power steering pump and the high pressure fuel pump UNDER the intake manifold!

                  You need to completely remove the actual heat exchange (The part that has two rubber coolant hoses clamped to it) from the engine where it is physically bolted to the cylinder head by 2 x 10mm nuts under the intake manifold next to the common rail!

                  I believe this is where the restriction to the turbo boost is happening where the 2 x 10mm bolts are!


                  Below is 2 x links on the description on how variable turbo works and how it dumps boost via the EGR valve.

                  Blocking EGR

                  And also this one below

                  Blocking EGR
                  Last edited by SWR; 18-02-2015, 01:49 AM.


                  • #10
                    Thanx again.
                    I have checked both. The pipe that is connected to the cylinder head, and the actual valve. Both seems open and fine. And I can stick my finger inside the cylinder head and can't feel anything wrong.

                    I have read the posts you are referring too, and I think I got the basics, but I still can't figure out why it's overboosting.
                    one thing I can't find on my car is the swirl flaps. Is that on newer models, or am I going blind?

                    I can post a picture of my engine compartment if that helps? Since there can be differences between EU and AU models ?


                    • #11
                      I just opened my MAF, and it seems clean from filter side, but it had a layer of dirt on the turbo side. Maybe that's my problem?


                      • #12
                        Well, it wasn't... I tried to clean it with brake cleaner, but didn't make any difference.
                        I took a video of my boost gauge, and will post it when I get to a computer.


                        • #13
                          This is where I'm connecting the gauge
                          Click image for larger version

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                          This heat exchanger is open, and doesnt have any plate blocking it
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                          I have checked and cleaned the valve
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                          When i check with an vacumgauge, i get various readings at the back of the EGR
                          Click image for larger version

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                          • #14
                            I tried to clean this, but made no difference
                            Click image for larger version

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                            I guess this one is the "main" EGR controller, but it is redusing the vacum.
                            Click image for larger version

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                            I have tried this from another vehicle, but with no luck.
                            Click image for larger version

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                            Boost gauge

                            It seems to me like the boost release is working like u\it should. I can hear the turbo spinning, and when i release the trottle it doesnt stall, but slowly slows down.

                            My problem is the "boost limiter" in lack of a better word.... what is telling the turbo to stop produsing more boost, and why is it working when the engine is cold...

                            I think i have explained myself wrong, since english isnt my primary language...

                            Im not shure how to get the pictures embedded in the post, but click the file name...


                            • #15
                              I tried to figure out what you ment by swirl control, but it seems like my car doesnt have them.

                              My vacuum runs like this: fom the pump, to a switch under the intake manifold, to a filter, then to the egr valve then from the egr valve to a blue switch. I think thats correct, but i dont know why there are two switches (valves)

                              The "boost lines" goes from the intake manifold, to a filter, the to a red switch (valve) then to the MAP sensor. Im not sure whate the red one does either.

                              I know I have a lot of questions, but after days of searching and reading, I know where to find the genies