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Thread: 2jzgte #2 turbo IACV opens on idle

  1. #1
    the Afterbirth Tycoon Automotive Encyclopaedia PlacentaJuan's Avatar
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    Default 2jzgte #2 turbo IACV opens on idle

    the INTAKE AIR CONTROL CALVE that allows the #2 turbo compressor to feed the engine opens when the throttle is cracked.

    i noticed this when playing around with something else in the engine bay and say it moving.

    it is 'powewered' by stored pressure in the pressure tank so will only get 3-4 good openings before the pressure runs out at idle.

    i am assuming the solenoid is getting triggered by the ecu but cant think of why this is.

    im pretty sure this is bad because it would allowthe #2 turbo to backspin with boost from #1.

    the recent changed i have made are: highflowedturbos : cant see how this would affect it.

    engine stripdown and rebuild: also cant see how this would affect it unless i have crossed a pressure line somewhere but the fact that it is opening and closing suggests the fault is in the solenoid.

    from what i understand this is one of the last actuators that should be activating at over 3000rpm.

    any ideas?

  2. #2
    Is a Chief Engine Builder wilbo666's Avatar
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    Default Re: 2jzgte #2 turbo IACV opens on idle

    You are correct in your statement that the ISCV should be closed before the rear turbo comes online. And it is bad that it isn't

    My suggestions,

    Step 1) Get a multimeter / test bulb and see if the solenoid is actually being activated by the engine ECU / a short along the control wires for the VSV...

    Step 2) Check to see that the VSV is working correctly, i.e. it doesn't allow the stored pressure through the valve when OFF.

    Cheers
    Wilbo
    Wilbo's Wiki (Includes 2JZ-GTE Wiring, etc! )

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    the Afterbirth Tycoon Automotive Encyclopaedia PlacentaJuan's Avatar
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    Default Re: 2jzgte #2 turbo IACV opens on idle

    Update;

    Have swapped ecu's

    Swapped the Iacv solenoid

    Disconnected the solenoid from loom to prove that it is getting a signal to open (it doesn't actuate when disconnected)

    And it is still opening when the throttle is cracked.

    Next step I guess is to test the loom but it is obviously getting a signal to open at a particular time: throttle opening. Which is wierd

    I would like to know if this is still happening while driving

  4. #4
    Junior Member Grease Monkey
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    Default Re: 2jzgte #2 turbo IACV opens on idle

    Does it also happen at full throttle? What about the valve in the exhaust that feeds that turbo? I can see them all being opened for fuel economy purposes at low loads (when you don't need boost response it could just open everything to reduce restrictions). However I don't know anything about the 2JZ sequential system, it's just a 'possible scenario'

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    the Afterbirth Tycoon Automotive Encyclopaedia PlacentaJuan's Avatar
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    Default Re: 2jzgte #2 turbo IACV opens on idle

    Yes I do not know what it's doing under load and the turbos feel fine when driving.

    Have just noticed that the valve is actually opening when the throttle begins to CLOSE!?

    Makes me think more that it is acting like a blow off valve?

    It's definately getting a signal to open (proven by it not opening when the plug is disconnected) and its not random like a short circuit it's allways opening with a trigger of the throttle closing.

  6. #6
    Junior Member Backyard Mechanic
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    Default Re: 2jzgte #2 turbo IACV opens on idle

    Are you actually having boost problems? Could be a number of reasons to open it at idle.

  7. #7
    Junior Member Backyard Mechanic
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    Default Re: 2jzgte #2 turbo IACV opens on idle

    I had a look at mine the other day (have an issue with no power under full load) and the inlet to no.2 as well as the exhaust valve for no.2 will open if the engine is revved in neutral. Didnt notice if it was on closing or not, but that would make sense: if you rev in neutral, no.1 will make some boost (not much) so when the throttle closes, pressure would rise and no.2 would open. Am also running hi flows (supposedly! I have yet to confirm), PowerFC, EBC, big exhaust etc...no issues making boost (15psi at under 2000rpm) however of late, once it hits 4000rpm it just dies off (only way to describe is its like driving along and putting the choke on on a carby car?)

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    the Afterbirth Tycoon Automotive Encyclopaedia PlacentaJuan's Avatar
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    Default Re: 2jzgte #2 turbo IACV opens on idle

    Daddio thanks for the info mate that really helped, I have pretty much stopped worrying about it.
    It would also explain the funny BOV sounding noise I have always had even though the stock BOV has been disabled.
    I have high flows too btw and if you are getting 15psi under 2k rpm I assume you have boosted the first turbo or are running ttc mode?
    If still sequential then what method have you used to increase boost?

  9. #9
    Junior Member Backyard Mechanic
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    Default Re: 2jzgte #2 turbo IACV opens on idle

    I still have stock, plumbed back BOV, and it works fine
    Probable reasons for getting 15psi under 2000rpm: Big dump (3.5"), big exhaust (full Apexi 3.5" system, hi-flow cats, no restrictors) are the main reasons I believe. EBC (GReddy Profec). Running sequential mode, I have never even tried TTC!! A couple people have examined my tune (done by Xspeed many years ago for previous owner) and said it has a lot of timing down low, and much less up top...I dunno, I am not a tuner, but it seems to work pretty well

  10. #10
    Junior Member Domestic Engineer
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    Default Re: 2jzgte #2 turbo IACV opens on idle

    its supposed to open the IACV to allow excess pressure to bleed off, in essence using the no.2 as a recirc valve, its pressure from the pressure tank (under the IM) doing this.

    Dave, sounds like you have the IACV VSV hoses on the wrong way, which is causing the 2nd turbo not to come online!

    should be connected as per second diagram

    http://mkiv.supras.org.nz/articles/andy.htm
    Current: 94 jzs147 aristo, 92 ep82gt starlet
    Prev: ma61, gz20, jza70, uzz31, ncp10r, 92 sw20r
    And the winner of the big car race is......HOT ROD ZOIDBERG!

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    Junior Member Backyard Mechanic
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    Default Re: 2jzgte #2 turbo IACV opens on idle

    Quote Originally Posted by woggin View Post
    its supposed to open the IACV to allow excess pressure to bleed off, in essence using the no.2 as a recirc valve, its pressure from the pressure tank (under the IM) doing this.

    Dave, sounds like you have the IACV VSV hoses on the wrong way, which is causing the 2nd turbo not to come online!

    should be connected as per second diagram

    http://mkiv.supras.org.nz/articles/andy.htm
    If that was for me, then: no vac hoses have been changed in the last 7 years (other than removing one at a time to check for leaks, and replacing with cable ties at each end for security) and mine are connected correctly for sequential operation

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    Junior Member Domestic Engineer
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    Default Re: 2jzgte #2 turbo IACV opens on idle

    have you tried switching to true twin Dave??

    maybe the rear turbo is shot?? if u go TTC, as per my link, u shud get an almighty rush from 3-3.5k onwards, if u dont, u know no.2 is dead, if u do, your sequential system isnt working correctly!
    Current: 94 jzs147 aristo, 92 ep82gt starlet
    Prev: ma61, gz20, jza70, uzz31, ncp10r, 92 sw20r
    And the winner of the big car race is......HOT ROD ZOIDBERG!

  13. #13
    Junior Member Backyard Mechanic
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    Default Re: 2jzgte #2 turbo IACV opens on idle

    Quote Originally Posted by woggin View Post
    have you tried switching to true twin Dave??

    maybe the rear turbo is shot?? if u go TTC, as per my link, u shud get an almighty rush from 3-3.5k onwards, if u dont, u know no.2 is dead, if u do, your sequential system isnt working correctly!
    I havent tried TTc yet...I guess I could give it a go
    I suspect the second turbo may be stuffed..am hoping not!

  14. #14
    Junior Member Domestic Engineer
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    Default Re: 2jzgte #2 turbo IACV opens on idle

    sure fire way of checkin goin ttc
    Current: 94 jzs147 aristo, 92 ep82gt starlet
    Prev: ma61, gz20, jza70, uzz31, ncp10r, 92 sw20r
    And the winner of the big car race is......HOT ROD ZOIDBERG!

  15. #15
    Junior Member Domestic Engineer
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    Default Re: 2jzgte #2 turbo IACV opens on idle

    if u need help wit it, (instructions are lil iffy if u dont have experience with all the actuators n line n shizz) pm me!
    Current: 94 jzs147 aristo, 92 ep82gt starlet
    Prev: ma61, gz20, jza70, uzz31, ncp10r, 92 sw20r
    And the winner of the big car race is......HOT ROD ZOIDBERG!

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