Does CRD GU8 require EGR block etc.

[Beni C]

The Ferret isn't doing them anymore but apparently Mudski who's on here us doing them now

Don't slap it, tap it!!!!

Awesome thanks mate, will hit him up!

[axl100]

I have 2012 Patrol and the other day i blocked the egr. Checked it with my scan gauge 2 throw a code and deleted it but it keeps coming up as pending codes p0401. Also notice my boost has reached 18.5 psi. When driving it the boost varies from 9 psi upwards and that with the cruise control on.

[Maxhead]

I have 2012 Patrol and the other day i blocked the egr. Checked it with my scan gauge 2 throw a code and deleted it but it keeps coming up as pending codes p0401. Also notice my boost has reached 18.5 psi. When driving it the boost varies from 9 psi upwards and that with the cruise control on.

You could try and drill a 8 to 10mm hole in the blocking plate to eliminate or at least reduce the errors. Seems the GU8's tend to boost a lot higher from what I've been reading but I'm going to install a dawes valve on mine just to be sure and limit the boost around 16psi. I'm getting cruising boost of 22psi when cruising with no load at around 100ks...There was a good thread on here somwhere how the boost spike works when cruising

[Maxhead]

Yeah this was it...

I think it's something to do with the egr valve opening and closing at cruising speed/lower engine loads.

Not sure if this is correct:

1. At idle Egr opens to let crap exhaust recirculate
2. You accellerate off and egr closes and boost comes on (high egts)
3. You hit cruising speed. Ecu reads there's low (less than ~55%?? on scangauge) engine load and cruising. Ecu opens the egr valve (even though it's blocked)
4. Bosst pressure increases as more air is flowing??? egt lower
5. Accellerate (more load) egr closes, less boost, more fuel = higher egts

Sooo this happens even on a stock CRD. Try it...
Get up to 100 and cruise. When you are going slightly (less load) down hill you'll notice boost increases.(egr opening) EGTS go way down as more air is flowing
Tap the accellerartor and egr closes and boost goes lower and egt rise as more fuel is being pumped with less air.


Bigger exhaust just makes the boost value slightly higher
Then the EGR block raises the boost even more.

Just what i think what happens. Might be wrong.

[axl100]

You could try and drill a 8 to 10mm hole in the blocking plate to eliminate or at least reduce the errors. Seems the GU8's tend to boost a lot higher from what I've been reading but I'm going to install a dawes valve on mine just to be sure and limit the boost around 16psi. I'm getting cruising boost of 22psi when cruising with no load at around 100ks...There was a good thread on here somwhere how the boost spike works when cruising

Well as far as i have been told that the CRD can handle more boost than the old DI. I have heard of someone that has blocked his egr and has a chip it installed has set his boost to go no more than 24 psi..

[Maxhead]

Well as far as i have been told that the CRD can handle more boost than the old DI. I have heard of someone that has blocked his egr and has a chip it installed has set his boost to go no more than 24 psi..

Also, when I blocked my EGR it would only boost to around 18 which I thought would be fine but then took it to Nissan for warranty TPS replacement and since then its been boosting to 22psi. I reckon there might be a new ECU firmware/software to make them boost higher....not sure though.

[Beni C]

Been doing a fair bit more research on this and have found that a lot of people that have done the EGR block on the CRD are reporting higher boost pressures.

So to state the obvious the gunk build up in the intake manifold is due to the exhaust gases mixing with the blow by from the PCV system, so it does pay to take one or perhaps both out of the equation. Interesting though, as I was looking through the electronic service manual it appears that within the PCV system there exists a oil / air separator.

The car goes in for a 100000k service after which the Provent / Scanguage and blocking plate will have arrived. I will fit the Scanguage and Provent first and see how the car behaves then I will fit the block plate and report back findings so watch this space. Being the first turbo and diesel that I have owned I am a bit wary about these boost pressure figures.

Has anyone actually ripped the intake manifold off a CRD with no block or catch can after a considerable amount of k's to see exactly how much gunk has built up? It appears to me that with the oil / air separator already existing within the PCV system that perhaps Nissan cotton on to the fact that exhaust gases and blow by was killing donks.

[Blacklotusdog]

Yeah few threads around with build up after 100,000km pretty bad in some. Either on this forum or the "other" patrol forum.

[Drew]

Well I've just found error code 0401 on mine if that coz of the blocked egr then I spose it happens sometimes to some people.

[Kennyj1976]

Thanks guys very useful - doing this mod this weekend