What happens when you block the EGR on the 3.0 engine

[Barrbeast]

Was looking at one of the Aussie Trol forums and came across this, which explains why blocking the EGR on the 3.0 can cause overboost (which can melt the cylinders as it causes them to run hotter). For those that don't know the 3.0 ECU has an overboost protection system - when the ECU detects overboost it goes into a sort of limp mode and the throttle will stop working. Take your foot off the pedal and it resets the system and everything will go back to normal but if it starts happening often it should be taken as a sign that all is not well and you need to find out what's happening as too much overboost occurrences will knacker the ZD30 engine

"What you will find is happening is when you block the EGR you are effectively increasing your EGT's because now you have that little bit extra of exhaust which was going through your intake but now has to go out where it should. The exhaust. So, when you get higher EGT's your ECU will compensate for this and increase the boost to pump more air pressure in to lower the EGT's. Therefore, sometimes giving you limp mode. So, there is two options here. Don't block your EGR, or block the stupid thing off and install a Dawes valve to stop the over boosting issues and while your at it, put in a needle valve and your car will go like it has never before."​

 

[Lazy-Ferret]

Was looking at one of the Aussie Trol forums and came across this, which explains why blocking the EGR on the 3.0 can cause overboost (which can melt the cylinders as it causes them to run hotter). For those that don't know the 3.0 ECU has an overboost protection system - when the ECU detects overboost it goes into a sort of limp mode and the throttle will stop working. Take your foot off the pedal and it resets the system and everything will go back to normal but if it starts happening often it should be taken as a sign that all is not well and you need to find out what's happening as too much overboost occurrences will knacker the ZD30 engine

"What you will find is happening is when you block the EGR you are effectively increasing your EGT's because now you have that little bit extra of exhaust which was going through your intake but now has to go out where it should. The exhaust. So, when you get higher EGT's your ECU will compensate for this and increase the boost to pump more air pressure in to lower the EGT's. Therefore, sometimes giving you limp mode. So, there is two options here. Don't block your EGR, or block the stupid thing off and install a Dawes valve to stop the over boosting issues and while your at it, put in a needle valve and your car will go like it has never before."​

That makes interesting reading, surely that could apply to any Turbo/EGR engine?

 

[Barrbeast]

That makes interesting reading, surely that could apply to any Turbo/EGR engine?

Certainly the increased EGTs bit, might depend on the ECU whether the boost increases etc. I reckon all worth bearing in mind though :thumb2

 

[firebobby]

Certainly the increased EGTs bit, might depend on the ECU whether the boost increases etc. I reckon all worth bearing in mind though :thumb2

I won't be messing with mine, keep it standard :thumb2

 

[terrano bob]

I won't be messing with mine, keep it standard :thumb2

that's the one :thumbs

 

[Thomas-the-Terrano2]

So how much exhaust typically goes through EGR at max opening.

 

[bud]

re first post, the Zd30 basically relies on the EGR as an external wastegate aswell as exhaust gas recirculation to keep emissions down.

Long story short, without it, creates the mentioned piston melting head cracking environment,.

what you could do if you really wanted to block the egr off but still avoid the issue is plumb the egr valve back in to the dump pipe beyond the turbo effectively creating an external waste gate. The ECU will still think everything is dandy but keep the inlet manifold pressure at a safe level.

 

[makeitfit]

You can also fit a decent bore exhaust system. That helps flow the gasses out quicker and reduces the EGT gains.
However on the Terrano, keeping it std is all well and good if the EGR is actually working properly. if not and it's blocked off you may get all of 30 odd degrees( less than 5%) more on your gauge. (measured post turbo) Diddly do das to worry about.
"Keep Calm and Block it Orff "