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Discussion Starter #1
Hi guys, on my trip to the northwest last week on a 47 degree day in an attempted overtake at 110kms an hour i had a loss of power and boost. i had recently had a dawes valve installed and 33's fitted. boost was showing 15 then dropped to 6 and wont go past that.
it feels like turbo is not spooling up but am showing minimal amounts of boost will the manifold still create that pressure even without the turbo working?

any ideas or questions to help solve this cheers

its an 06 guiv zd30, dawes valve, boost gauge
 

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Sounds like you have popped off a boost or vacuum line..

Did you personally install the dawes valve?
 

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Patrolen
check the vacum to your turbo by removing the vacum hose from the turbo dose the vnt arm (solonide arm ) go down when you remove it and back up when it is put on ?
if the arm goes up and down then you are geting vacum to the turbo so thus you should be geting boost .
i would suggest checking the pnp switch (park neutral postion switch)it is on the gear box if this switch fails it will limit your boost.
While you are drving try moving and putting pressure on your gear stick to see if you can get power back this some times works or you will have to get a scan tool and check it or remove it and check it for continity.
If this tests all ok
check your maf sensor or simply replace it with a knowen good one (maf sensor )
give this a crack mate you can test these in what ever order your wish but they are the most common things to limit/stop boost/reduce power
good luck
 

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Discussion Starter #4
Sounds like you have popped off a boost or vacuum line..

Did you personally install the dawes valve?
no i got it professionally installed, i checked the hoses when i got there they were all in place, i will pull them off and check for splits in them
 

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Discussion Starter #5
Patrolen
check the vacum to your turbo by removing the vacum hose from the turbo dose the vnt arm (solonide arm ) go down when you remove it and back up when it is put on ?
if the arm goes up and down then you are geting vacum to the turbo so thus you should be geting boost .
i would suggest checking the pnp switch (park neutral postion switch)it is on the gear box if this switch fails it will limit your boost.
While you are drving try moving and putting pressure on your gear stick to see if you can get power back this some times works or you will have to get a scan tool and check it or remove it and check it for continity.
If this tests all ok
check your maf sensor or simply replace it with a knowen good one (maf sensor )
give this a crack mate you can test these in what ever order your wish but they are the most common things to limit/stop boost/reduce power
good luck
thanks mate ill try these things, i know the maf is good had it tested when dawes was installed but no harm in trying another, with this PNP switch where abouts on the gear box is it? its an auto
 

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patrolen
i just asumed its a manual i pretty sure but dont qoute me the autos dont have a pnp switch that operates in the same princabels ill have a look in a minute i have a w/s man here but i would defintly try a knowen good maf they are a strange thing to test they will test ok but still be stuffed like most electrical things i surpose i will get back to you on the switch
 

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Discussion Starter #7
check the vacum to your turbo by removing the vacum hose from the turbo dose the vnt arm (solonide arm ) go down when you remove it and back up when it is put on ?

ok just did this and it went down when i took it off and up when put back on does this rule this out as a problem?
 

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patrolen
When that arm goes up it releases the the little legs in the turbo which in effect allow it to spool up so from a visual point of view it would seem that the problem is not in the turbo.
altough the little legs can get stuck but that is a whole diffrent issue and by the way you have desicbed your issue it is not the case.
I have had a look and no there is no pnp switch fitted to the auto they use a control module instead so this rules this out as a possibel issue.
So really we are back at the maf sensor as being the most likley issue you could also try a code check but sadly i dont know how to get codes the manual way (i need my little heart rate monitor for stuff like that lol) it will be on here some where how to do a code check.
try doing a code check and see if that brings you any luck and i would deffintly try a maf sensor based on the way it all happened it sounds very elecrtical related
good luck
 

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Discussion Starter #9
thanks alot for your help ralphn ill replace the maf tomorrow, i hope thats the problem. otherwise it maybe an expensive outcome.
 

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do you have a needle valve installed mate?
 

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Go Hard or Go Home
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Sitting on 110 then lose boost no acceleration, OP has not bypassed ecu for boost control, even though only went to 15psi then down, to 6psi accelerated has boost again. still sounds like overboost issue.
 

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x 2 sounds like overboosting and going into limp mode. Mine does this still as I have not fine tuned the spoolup rate quite wright yet. If you come of the peddle and jump back on it again does it go away?
 

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Go Hard or Go Home
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Thats why he should check for faullt codes & check the MAF guys, as per ralphn's post, its a common cause for boost issues.

If its not the MAF or there are no codes, then dive in deeper to find the issue, like install a needle valve to control the spool rate, unless he wants to adjust the VNT screw on the turbo to reduce the spool rate. But this is after checking the simple things first.
 

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Sitting on 110 then lose boost no acceleration, OP has not bypassed ecu for boost control, even though only went to 15psi then down, to 6psi accelerated has boost again. still sounds like overboost issue.
i had mine overboost happend at around @13psi. it is not how much boost you may got, but how it spoooool up. i finally adjusted the needle valve to slow down the spool rate, the car can no boost up to 16psi without any issue.
to me, it doest not like anything to do with maf?
 

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Discussion Starter #19
no ecutalk, im doing maf today, it dosent feel like limp mode it feels like i have no turbo at all like the motors doing all the work but im still showing boost pressure (max 6psi) and it takes a while to get there which i find strange.
 

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i had mine overboost happend at around @13psi. it is not how much boost you may got, but how it spoooool up. i finally adjusted the needle valve to slow down the spool rate, the car can no boost up to 16psi without any issue.
to me, it doest not like anything to do with maf?
With mine, it too can show symptoms of over boost with 16psi, I too adjusted the needle valve to stop this from happening. My readings on the ECUtalk MAF voltages showed ~4.25 volts with aggressive spool rate, and was a lower reading of ~3.85-4.0 volts when I opened the needle valve, hence why IMO, I believe its got to do with the MAF & ECU.
 
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