GU ZD30 DI NADS Help

[lil regy]

Hey guys, Long time lurker don't post much.

I have a GU ZD30 and auto. I have replaced the injector pump, injectors, and head within the last 10-15k kms.
I Blocked the EGR and fitted a boost gauge and drove around for a while. when cruising I would notice the boost gauge to spike to 20+ then fall away to around 10-15 and stay there while accelerating. while cruising on the freeway I could hear the intake change noise and the boost climb to 15 and sit there. But here's the issue.....

I have now fitted a Dawes valve to the car. 'No matter what I do whether it be full throttle or revving it out I can't get it to boost above 9-10psi. it barely gets to 5psi before 2500rpm and is just a slow bucket of puss . I cant keep the EGT under 480 while cruising at 100 and I cant get it to accelerate without reaching EGTs of 500-550+. Why has the Dawes valve made the car worse n not better ??

Can anyone please help me?

[threedogs]

you need to get your boost up to 10 psi for 100kph, your max will be around 15-18 psi with spikes to 20 maybe.
After you have your boost set right adjust the needle valve for your spool up rate
Take note where the dawes is now and screw it "IN" one full turn and lock it off.
Go for a drive and see what boost levels you are acheiving, keep doing this till max boost is as above

[lil regy]

Cheers. I have gone from all the way out to all the way in on the dawes valve and still cant get anything above 9-10psi.... cruising at 100 im getting 4-5psi. when I give it a boot full its slowly climbs to 8psi but my EGTs rise stupidly like the ecu is expecting 15psi

[the evil twin]

Sometimes but certainly not always you need to slightly stretch the spring on the Dawes to get enough spring pressure to get the boost up.

[mudski]

Have you installed a needle valve aswell?

[lil regy]

no needle valve yet. will be doing that Monday..
from what I read the needle valve improves the delivery and can select the range of the boost but not the maximum... When I installed the dawes valve I expected to lose the spikes of boost that go to 20 but not also reduce the peak to 10.

[SG1]

Was doing my head in adjusting the dawes and needle valve when I first installed it, ended up being MAF issues and once I sorted a replacement it was a lot better. Trying to get the same psi ranges with the auto at the speed and rev ranges suggested for installing the dawes valve was very difficult because of the Auto trans and how at 100 it sits in the low 2000 rpm range (2100-2200 there abouts instead of what the manuals sit at 2600-2700 maybe?), hope you figure it out soon, maybe double check its all plumbed correctly with no leaks.

On a flat road with cruise on my boost will sit at 4-6psi at 100k's with the auto, but rises quite easily with an incline or a bit of load.

[mudski]

no needle valve yet. will be doing that Monday..
from what I read the needle valve improves the delivery and can select the range of the boost but not the maximum... When I installed the dawes valve I expected to lose the spikes of boost that go to 20 but not also reduce the peak to 10.

Worry about it once you have the needle valve in. Whilst the needle valve controls spool up and mid range boost it still affects max boost to a point.

[lil regy]

cheers guys. will buy and install the needle valve Monday and et you know the result

[threedogs]

Was doing my head in adjusting the dawes and needle valve when I first installed it, ended up being MAF issues and once I sorted a replacement it was a lot better. Trying to get the same psi ranges with the auto at the speed and rev ranges suggested for installing the dawes valve was very difficult because of the Auto trans and how at 100 it sits in the low 2000 rpm range (2100-2200 there abouts instead of what the manuals sit at 2600-2700 maybe?), hope you figure it out soon, maybe double check its all plumbed correctly with no leaks.

On a flat road with cruise on my boost will sit at 4-6psi at 100k's with the auto, but rises quite easily with an incline or a bit of load.

Mine is an auto and sits on about 12 @ 100kph,, max boost is around 20 psi.