I have just over 25k on my 05. I've had the EGR disabled for 99.9% of the engine life. I was replacing my intake elbow and noticed how dirty the intake was. I run fuel additive with every tank of fuel too.

Anyway, I pulled the EGR valve to inspect. It wasn't gummed up, but full of soot. I cleaned it, but I have some questions:

1) I could push it open with my finger. So even though it is disabled, how often is the exhaust pressure > the intake pressure? Is this causing it to open and gunk up my intake?

2) Instead of disabled, if it was commanded shut with a tune, can a pressure difference *still* open it?

3) Looking closely at the system, there seems to be 3 chambers in it (seperated by 2 valves on the EGR). The lowest one is the intake chamber. The middle one looks like the exhaust chamber. So what's the upper chamber? It looked really gunked up.

4) I previously thought the EGR flow was from the passenger side only. But the system looked like exhaust flow comes from both sides. Is this right?

Thanks!!

 

1) exhaust pressure can open the valve and may cause gunking.
2)EGR is commanded open and closed by spring pressure.
3)Air intake from CAC, exhaust from EGR cooler, and the two sides of the intake to heads.
4) exhaust enters the intake through the cooler attached at the passenger side uppipe and delivered through the EGR valve when opened to the intake manifold runners

 

Thanks. Also found this: http://dan.prxy.org/Truck/6L_bible_h.../Page_037.html
So there really isn't a 3rd chamber, the exhaust gases just flow both ways into the intake manifold.