6nz c15 weird on going high EGT issue, unloaded

Mbn engine has no differences to handle the heat. Other then burning out the divider in the manifold and cracking turbine housings over time the engines didnt melt down.

Sounds like your wastegate is adjusted on the tight side. It should be fully open by 28psi. Heck it might not be opening at all. What does the A/R number stamped on the exhaust housing say.

 

Where is your pyrometer probe installed?
Pre turbo or post turbo?

 

My 6NZ has the probe post turbo.

Could it be that the hose to the wastegate is plugged, blocked, or leaking? It seems that would be the only way that shop air activates the wastegate and that you get in excess of 30 psi boost while driving. If that hose is leaking that would contribute to higher egt as well.

 

Here is the general performance data for your engine. You can see @ peak torque the exhaust temp measured after turbo (stack) was 985 F. Stock turbo should be a 1.42 AR on turbine side( Garret GTA4702BS).

 

Yes it sounds like the wastegate is working fine with shop air. Still seems like it's not opening all the way under normal driving conditions thou.

The reason I ask about A/R on the hot side is because it should be 1.42 . They did have a 1.28 on some 550hp E models like the 1lw that did seem to run hotter egts with higher boost #s. It was really responsive turbo but was a little to small in my opinion.

 

You'll see the A/R # on the side of the snail close to the flange at manifold.