Dangers of Blocking EGR

Yes this is the risk of blocking the EGR. The soluton is to not fool the computer, but to fool the boost controller which is a simple vacuum operated actuator on the "wastegate" (variable vane type).

This is a practice widely used on normal waste gated turbos by the rice burner brigade, and simply requires a manual boost adjuster readily available and costing $50. The adjuster is plumbed into the vacuum hose gong to the actuator. The adjuster has a spring and ball seal that once pressure (vacuum) reaches a certain amount (adjustable) then it leaks a small fraction of air into the vacuum hose, thus changing the actuator position and raising boost.

Low boost at cruise was always a problem on my Patrol, without the EGR blocking. I believe high EGT is the cause of the engine failures on vehicles that have not blocked the EGR system, due to low boost at highway cruise when fueliing is high. This is particulary when towing. It seems in my opinion, an engine manaegment issue that aids the Patrol meet emmission specs and therefore can't be engineeered out causes the problems. Of course Nissan can't fiddle with emissions laws, so the fix is to make the engine tolerate higher EGT by adding more oil, ceramic piston tops etc etc.

Now while Nissan my not want to fiddle with emissions control, there are owners who happily would. Increasing boost to more reasonable levels at highway cruise seems a logical place to start lowering EGT. This is easily done with a manual boost adjuster, a very common mod on just about every rice burner you see cruising our streets full of young people.

I am not sure that I understand the relationship between the blocked EGR and the variation in boost pressure? One of the EGR's jobs is to direct exhaust gas back into the cylinder to aid in the cooling of the combustion process. It does this due to the fact that the exhaust gas has a lower oxygen content than the intake air and thus does not burn as well and in fact will partially extinguish the combustion process. So if the engine management system still thinks the EGR is working and therefore delivering the same amount of fuel for a given engine load, I would expect to see a rise in EGT if the EGR is blocked. The boost pressure is affected how ? Under full throttle the EGR is blocked by the ECU supposedly. Maybe there is another reason the boost drops off? I would be interested on peoples theories for this?
I have a 2003 3.0ltr manual with around 120,000klm. I have had the car from new. My EGT runs at anything around 300 to 450 at around 100 - 110klm/h on most roads. I have seen it as high as 600 on a long steep hill at 110klm/h and full throttle, but I wouldn't hold it there. I do not have my egr blocked, nor do I have a Dtronic etc or any other mods to the engine.

Yes the boost is dropped by the actuator. It seems to drop boost at certain revs. You can predict the exact point it will drop boost as you are driving along. I know some people have reported a drop in boost at highway cruise due to the EGR blocked, but I've not noticed this. Mine always was low at highway cruise, due to the action of the VVT at about 2100-2200 rpm. As I say I see this as an engine management issue. Low boost would be required when the EGR is wide open (at highway cruise) otherwise the gases may never flow into the intake at high pressure. But with the EGR blocked this is not an issue.

So you can see Nissan's dilema. if they make the car run higher boost at highway cruise (in order to lower EGT) they will have to disable the EGR, which means the car won't meet emmission specs. So the answer is build engines that can tolerate more heat, and fix the old ones when they blow up.

Hi

Isn't the EGR there to minimise noxious exhaust emissions that stuff up the enviroment?

If the answer is yes, why would anyone want to deliberately stuff up the enviroment by doing engine modifications for very little gain and possibly contribute to a very bad future for your and my grand kids?

Phil