Boost levels at crusing speed

[mundlich69]

Hi All,
Just after your experiences and thoughts on how the boost should be behaving when travelling over 100kmph??
I've had a ultra gauge hooked up to the GU8 not long after the purchase and probably 3 months ago I noticed when cruising over 100kmph especially with cruise control engaged the boost level would rise from a consistent 12-13psi upto 17psi and fall away it was an iregualur occurance but something I kept an eye on and adjusted my driving to suit. I mentioned it to Nissan when it went for it's 10000k service and the found a faulty EGR valve which has since been replaced. Problem is it's doing more often now and has climbed upto 18psi on occasion. Took it back to Nissan and they spent a day on it could not find any issues, next step is they want it overnight so they can hook the computer up and take it for a run which is fair enough. I told them I'm getting all the upgrades installed this week (including new intercooler, exhaust and chip) so I see how it preforms when I get it back and if there's still an issue I'll bring it back.
Now firstly is there an issue (is the boost suppose to act this way) and secondly any recommendations???

[alfonso]

I dont have a boost gague but my 2012 dx ute makes a different sound when I get to cruising speed in 3rd fourth and fifth gears almost like the clutch is slipping usually around 2500 revs and when I let my foot off just a little. sounds like when you first start up and the oil hasn't stuck yet could this be boost also.

[paulyg]

How does it behave with out the cruise control on? I now with mine the boost does move up and down a lot more with cruise control on.
Could be the cruise control trying to maintain the set speed moving the throttle on and of.

[mundlich69]

It doe's the same thing with out cruise control on but not as bad and often??

[mudski]

Install a Dawes valve and block the egr and forget about those issues for ever.

I tapped that app

[kevin07]

check all your hose clamps but it does sound like an egr problem

[MEGOMONSTER]

My GU8 auto, EGR blocked chipped and zorst sits on flat roads at 100kph with cruise at a constant 10psi

[mundlich69]

I've checked all hoses and so did nissan all good there. I get the patrol back tomorrow so I'll see what differences all the mods have made to it.
Megamonster doe's your egr block have a 6mm hole or not??

[MEGOMONSTER]

Megamonster doe's your egr block have a 6mm hole or not??

It's MEGO MONSTER and I really couldn't tell, I just don't know, I don't even know where to look or what to look for.

[mudski]

These Nissan CRD's don't need the hole. For some reason. Just about every other CRD does though.