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Discussion Starter #1
Hi All,

OK I am confused. I had Robson 4wd fit a DAWS valve and they set maximum boost for the 13PSI. However I see on the forum that I need a needle valve or is this part of the DAWS valve??

Have I missed something here?
 

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ZD30 Out - L77 In!
nissan patrol
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Jack,

There are several configurations for fitting or setting up a Dawes valve, depending on if your EGR is blocked or not. If you still retain EGR operation, you don’t need the needle valve although I would think that 13psi is too low if that was the case.

If you have blocked the EGR, you should fit a needle valve along with the Dawes valve and bypass the ECU VNT boost control solenoid.
 

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Discussion Starter #3
OK Chaz, cheers.

They blocked the EGR at the same time. I didnt know about the needle valve, must have missed it. I asked them to do DAWS and EGR, they knew about the mods. So set it up for 13 PSI.

Do I need to get the needle valve? What does it look like and what damage could I do without it?

Here I thought I have done a proper job......

When I get back to West Oz in a couple of weeks where the Nissan is I will take a picture under the bonnet. But all I could see was some blue tube with the valve in the middle.

Will I have to have boost gauge to install needle valve?
 

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ZD30 Out - L77 In!
nissan patrol
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OK Chaz, cheers.

They blocked the EGR at the same time. I didnt know about the needle valve, must have missed it. I asked them to do DAWS and EGR, they knew about the mods. So set it up for 13 PSI.

Do I need to get the needle valve? What does it look like and what damage could I do without it?

Here I thought I have done a proper job......

When I get back to West Oz in a couple of weeks where the Nissan is I will take a picture under the bonnet. But all I could see was some blue tube with the valve in the middle.

Will I have to have boost gauge to install needle valve?
Jack,

If you have the EGR blocked and they didn’t bypass the ECU boost control solenoid, you will still get boost fluctuations, eg, your boost will drop under load when EGR is implemented by the ECU.

If they did bypass the solenoid as they should have, you will have no control over your turbo spool rate, which is why I suspect they adjusted it only to 13psi. If you fit a needle valve and set up the spool rate correctly, you should be able to set the Dawes valve to 15psi without any limp mode problems.

Have a look HERE for a bit more info and yes, you should have a boost gauge to set it up correctly.
 

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Discussion Starter #5
OK bugger, it will have to wait to go back to Perth some day. I dont have the facilties onsite to do any mechanical work.

I took it to them to insure I get a few more kms out of the old girl. It has done 250k KMs.

I do plan to fit a boost gauge etc, just need the facilities to do it.

Was going to do a intercooler upgrade and think a lot have the port already for boost gauge.

Oh well, here I thought I would have time to do other mods and I was smart to get EGR and DAWS fitted. Not knowing that I need needle valve does as well.

It runs well and has heaps of power etc.
 

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ZD30 Out - L77 In!
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What you have done should help to at least eliminate the chance of overboosting and reduce the amount of soot in your oil. It’s a step in the right direction, but there is more you can do.
 

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Discussion Starter #7
Just a note Robson 4wd did a great job and done what was asked of them.

Craig there was very helpful. I missed getting the needle valve done.

I have sent Craig this link for his suggestions.
 

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Just out of curiosity, did you supply the parts, or did you just drive in/drive out.... and how many $$$

I'm looking at doing the NADS stuff but not really sure what I'm doing.... If I could just walking in with a Gauge, Needle valve, EGR block plate and Dawes valve and say "Fit it all please" that would be really handy...
 

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Rob,

You could also try United Fuel Injection in Redcliff, had my EGR blocked and Dawes valve supplied and fitted for $300.00. They seam to know their stuff and put the Patrol on the dyno as well. Nothing against Robson Bros as I use them to service my Patrol, United were, at the time I had my work done, cheaper.

Regards Matt
 

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Do you think they would also do the needle valve aswell ?. Even after trawling around the forum i've managed to get an understanding of what the dawes valve is for, but the needle valve is still intreging me

Sent from my MB525 using Tapatalk
 

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When I had my Dawes valve fitted I spoke to them about fitting a needle valve and they were not very keen on taking control off the turbo away from the ecu.

Regards Matt
 

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They will fit the needle valve if you tell them that's what you want. Or at least they fitted mine. Personally I think it's essential if your blocking the EGR. It also makes a tremendous difference to low down boost, which is not the ZD30's strength.
 

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I'm not looking for "More Power" as such, but if I can get the boost to kick in earlier I'd be happy (do lots of beach driving, taking off can be a pain in the @rse)


I sent them an email last night asking if they would do the job and for a supply and fit price and a fit only price (fit boost gauge, block egr, dawes valve, needle valve + set them correctly)

I'l probably end up getting the main parts myself and let them do the engine side install work and supply all the suplementary parts (extra hoses, T's, and whatever else is needed).

I'll post the reply if it arrives :)
 

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Jack,

If you have the EGR blocked and they didn’t bypass the ECU boost control solenoid, you will still get boost fluctuations, eg, your boost will drop under load when EGR is implemented by the ECU.

If they did bypass the solenoid as they should have, you will have no control over your turbo spool rate, which is why I suspect they adjusted it only to 13psi. If you fit a needle valve and set up the spool rate correctly, you should be able to set the Dawes valve to 15psi without any limp mode problems.

Have a look HERE for a bit more info and yes, you should have a boost gauge to set it up correctly.
if the boost control solenoid has been bypassed and the dawes valve set to say 13PSI, will it affect the turbo in any way other than spooling up to 13PSI?

will it still spool linear to the rev range?
 

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if the boost control solenoid has been bypassed and the dawes valve set to say 13PSI, will it affect the turbo in any way other than spooling up to 13PSI?

will it still spool linear to the rev range?
Yes, the turbo should still spin up and be linear to 13psi, but will probably go above that at full throttle when you exceed 3500rpm.
 

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Guys, if this Mechanic adjusted the VNT screw, is it necessary to fit a Needle Valve? I know its eaiser for fine tuning but is it absolutely necessary?
 

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Guys, if this Mechanic adjusted the VNT screw, is it necessary to fit a Needle Valve? I know its eaiser for fine tuning but is it absolutely necessary?
I never really understood a need for adjusting VNT screw.;)
Dawes valve takes care of maximum boost very well and needle valve will control spool up rate even easier.
Needle valve also allows you to take away the control of the turbo charger away from engine ECU and doing so taking away the fluctuations and idiotic design attempts to compensate for feeding the engine with its own exhaust crap.:( So if that part has been taken care of than there is no need for ECU to be in charge anymore.
With needle valve you've turned the variable geometry turbo charger in to standard fixed turbine turbo with added bonus having much quicker response (read spool up) than fixed geometry unit.
Back to your question though: NO it is not necessary but you'll be amazed with the result when doing so. :D
 

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I have read extensively through older threads on Dawes, needle, EGR blockage and the fitting of boost and pyro guages with view to getting these done to improve the running of my 2003 Patrol. I've fitted both the guages, Dawes but stopped at the EGR blockage and needle installations as I read that there were a number of problems with the vacuum (thread 2009) that was causing erratic running to occur.

The mechanic I used said that he had many clients come back to him with problems after blocking and needle install. I have the needle part and the blocking plate is easy to get but I really am in two minds about using them because of the quoted problems in the 2009 thread.

My Dawes is fitted at maximum on 15psi but since I have had it, it rarely goes above 10psi with high temps. You really have to rev the motor (2nd gear 4,500rpm to get 13psi) to get a high PSI, it seems to sit around 8-10 revving at 4000rpm through the gears and settles back to 5-6psi in 4th at 80klms. The temp stays between 300-450 depending on any small hills.

What is the current opinion on my concern re the vacuum question?

As you can tell I am not mechanically minded so take a lot of interest in comments made by senior members like Chaz and Whittie etc.
 

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ZD30 Out - L77 In!
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I never really understood a need for adjusting VNT screw.;)
Dawes valve takes care of maximum boost very well and needle valve will control spool up rate even easier.
Needle valve also allows you to take away the control of the turbo charger away from engine ECU and doing so taking away the fluctuations and idiotic design attempts to compensate for feeding the engine with its own exhaust crap.:( So if that part has been taken care of than there is no need for ECU to be in charge anymore.
With needle valve you've turned the variable geometry turbo charger in to standard fixed turbine turbo with added bonus having much quicker response (read spool up) than fixed geometry unit.
Back to your question though: NO it is not necessary but you'll be amazed with the result when doing so. :D
rumcajs,
I’ve found that after adjusting the VNT limiting screw, I can almost close the needle valve and still have a reasonably fast spoolup without the spike. Mine will boost smoothly up to 10psi and just stop without going to 12, then return to 10.

However, when I switch over to high boost, it will spike to around 16 before settling to 15psi. When this happens it isn’t an issue because I’m already above 2000rpm, so I don’t mind a small spike in that case.
Adjusting the limiting screw can make a good system just that little bit better and slightly more predictable. It’s probably a bit more beneficial with a single Dawes setup though.

Irish333 said:
My Dawes is fitted at maximum on 15psi but since I have had it, it rarely goes above 10psi with high temps. You really have to rev the motor (2nd gear 4,500rpm to get 13psi) to get a high PSI, it seems to sit around 8-10 revving at 4000rpm through the gears and settles back to 5-6psi in 4th at 80klms. The temp stays between 300-450 depending on any small hills.
Irish333,
It’s all about setting it up and tuning it correctly. There are three areas of adjustment, so I think something is not quite right in your case.

If you set the Dawes to 15psi, then it should go straight there once you are above 2000rpm with some load. If it’s set up correctly, you should have around 18psi at 4000rpm and full throttle.

Boost will always drop back when you lift your foot or take away the load, so it needs to be setup either on a dyno or driving up a hill to supply sufficient load where you can monitor rpm, boost setting and load or throttle position.
 
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