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Discussion Starter #1
Yesterday we fitted a dawes and needle valve, new CC intercooler and cleaned the inlet manifold on my friends ZD 30 july 94 model, it also has 3 " straight through pipe and provent fitted. Since fitting ( followed Chazs indtuctions wich we think we got right ) we are having problems with it going into limp mode. The dawes is set to give a max of 15psi. Going through the gears it will rev freely to red line, load it up going up a hill it will go into limp mode, lift off and re apply the throttle it will come on boost again.
What could be causing this problem, I have done a search and can't find anyone who has had this problem.
 

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Y2KGUII ZD Wgn
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I know you said you had the dawes set to 15 but does it go to 15 and stay there when you load it up, with the turbo spooling up quicker after the mods mine will go past to 17-18 briefly and drop back when the spring pressure is overcome, may be your spooling up too quickly, the 3" exhaust can have that effect some times.

Do you have the needle valve? if so what happens when you open that up a couple of turns.
 

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can we assume 2004 model ? Dont believe the 3ltr exsisted in 94

Are you certain of your boost readings ? as mine would only go into limp mode at about 22 PSI after I blocked the EGR.

If you can varify the boost that would be a good start and have you blocked the EGR?
 

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Yeah mine will go to about 18psi initially, then drop back to a constant 15psi. Interestingly my EGT's have dropped after a few days of driving, perhaps my ECU reset and has learnt to not be as thirsty on the fuel?
Saving up for the 2 3/4 exhaust now :)
 

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Y2KGUII ZD Wgn
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Yeah mine will go to about 18psi initially, then drop back to a constant 15psi. Interestingly my EGT's have dropped after a few days of driving, perhaps my ECU reset and has learnt to not be as thirsty on the fuel?
Saving up for the 2 3/4 exhaust now :)
Booked in for Beaudesert 2 3/4" system next week, will PM you and let you know how it works out.
 

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Discussion Starter #6
Yes sorry it is an 04, egt blocked, it will boost to about 17 and then settle on about 14. the boost guage is a VDO unit plumbed into the intercooler outlet pipe. It has a needle valve fitted, is it possible to have it around the wrong way ( 180 degrees ) as it does not seem to slow the spool rate very much.
 

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mine does exactly the same thing........ issue was spool up rate, my bost was never going over 18psi but it was spooling up to about 13-15psi at 2000 rpm... I just wound down the grub screw ( before needle valve ) and it sorted it out.
 

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Y2KGUII ZD Wgn
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Yes sorry it is an 04, egt blocked, it will boost to about 17 and then settle on about 14. the boost guage is a VDO unit plumbed into the intercooler outlet pipe. It has a needle valve fitted, is it possible to have it around the wrong way ( 180 degrees ) as it does not seem to slow the spool rate very much.
Double check the needle valve, I know there was at least one model that had a one way valve incorporated , if it is that one it will have an arrow indicating flow direction, if no arrow it is a plain needle valve.

My needle valve is a 1/8th bsp, when driving around the city I have mine about 2 turns open to get the effect I want and it will still spike to 15 then drop back 8-10.

You should have 5 - 6 lb when hitting 1500rpm, if you are getting much higher than that then this could be your problem
 

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Discussion Starter #10
OK further update, have got it running with only the occasional visit to limp mode. The dawes valve is screwed almost all the way in and will only make 14psi max. We would like to get it up to 16psi but there is no more travel available in the dawes, what could possibly cause this??
 

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Remove the spring from the dawes valve and stretch it a little, this will give you more adjustment/increase boost.

If its still going into limp mode, your spool rate it too fast. Open your needle valve to allow slower spool rate or stop overboost symptoms.
 

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Y2KGUII ZD Wgn
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Do exactly what Paul says, but when you stretch the spring do it in 5mm increments and retry, that way you will manage it better. Doesn't matter if you do it 10 times getting it right is the important part.

Try opening the needle valve 1/2 a turn at a time once you get your boost level near 16.

luckily enough mine doesn't go into limp but, 1/2 turn needle valve opening significantly reduces spike and thus spool rate.
 

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Discussion Starter #13
OK, had another play on the weekend, stretched the spring a bit and now makes 16psi at 3600rpm, have played with the needle valve to slow spool rate but we are still having issues with it going into limp mode, it is not constantly doing it but, when trying to accelerate up hill or hold speed on a steep hill it will limp out.
 

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Two up,

Have you bypassed the ECU at all by only having one hose running from the air box, will find pic to show were I mean. if so should not be getting limp mode.
 

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Y2KGUII ZD Wgn
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OK, had another play on the weekend, stretched the spring a bit and now makes 16psi at 3600rpm, have played with the needle valve to slow spool rate but we are still having issues with it going into limp mode, it is not constantly doing it but, when trying to accelerate up hill or hold speed on a steep hill it will limp out.
Have a pic of the vacuum switch bypass in my Dual Dawes album if you care to look. What boost do you have @ 1500 rpm, it should be no more than 5-6psi, check this as it could be causing a problem.

How much are you opening the dawes? on my first set up I had to open it 2 turns + to minimise spike (but for some reason limp has never been a problem on mine no matter how hard I push it), keep opening it up and see what happens.
 

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Discussion Starter #16
Geeyoutoo,

Do you mean picture # 7, also do you mean the needle valve, if so I am opening it enough so that the vnt actuator just moves off the stop.

Shane 3.0 did you manage to find that photo.
 

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Y2KGUII ZD Wgn
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Geeyoutoo,

Do you mean picture # 7, also do you mean the needle valve, if so I am opening it enough so that the vnt actuator just moves off the stop.

Shane 3.0 did you manage to find that photo.
# 7, That is correct, with regard to your needle valve, as an experiment just keep opening it up until you start to lose max boost then adjust it back a touch to still maintain max boost, then play around with acceleration and see whether it goes into limp. It might be you need to adjust the VNT.

Again, what boost do you have at 1500rpm with the needle valve closed.
 

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two up

I will take pic of mine, this is as per chaz'z diagram so yours should be similar

 
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