Help - I can't find PVC valve on my 98 EB V8 AWD

[Spdrcer34]

PCV is NOT used to recycle the unburned fuel (?) back to the engine.



PCV = Positive Crankcase Ventilation, so in other words, it is a 'Controlled Vacuum Leak'. What you had was a uncontrolled Vacuum Leak. And quite a sizeable one at that. That hole is nearly 1" in diameter. I would re-install the PCV, clear the codes, and see if you STILL have a Check Engine light coming on.

And the system that you described as, "I somehow understand that it is used to recycle the unburned fuel (?) back to the engine" That is the EGR system. Which stands for Exhaust Gas Recirculation. It helps burn fuel that would be otherwise unburnt. If the EGR system is not in place the fuel would burn in the catalytic converter, possibly shortening the life of the cat.

Ryan

 

[dcdyd]

Thanks for the description. I will do what you suggest here today after work. Would vacuum leak cause engine code P0153?

 

[1998Exp]

If he had a 1" hole in the vacuum side, the engine probably wouldn't run at all. Seems to me that he still had the valve connected to the vacuum port, but not to the engine. I believe that it would vent the combustion blowby from the cranckase into the air instead of sucking them into the intake manifold, the way it was done fifty years ago, before emission controlls came about.

As for the EGR function, that, unfortunately, is a common misconception. There is very little unburned fuel, if any at all, in a properly functioning engine. And even if there was, the EGR only recirculates a small portion of the exhaust stream, so it wouldn't do much about burning it. The purpose of the EGR system is to reduce the 'partial pressure' of the combustible mixture in the chamber by adding inert (non-combustible) gas, which what exhaust really is. This reduces the combustion temperature and prevents the creation of smog-creating NOx (nitrogen oxides).

PCV is NOT used to recycle the unburned fuel (?) back to the engine.
PCV = Positive Crankcase Ventilation, so in other words, it is a 'Controlled Vacuum Leak'. What you had was a uncontrolled Vacuum Leak. And quite a sizeable one at that. That hole is nearly 1" in diameter. I would re-install the PCV, clear the codes, and see if you STILL have a Check Engine light coming on.

And the system that you described as, "I somehow understand that it is used to recycle the unburned fuel (?) back to the engine" That is the EGR system. Which stands for Exhaust Gas Recirculation. It helps burn fuel that would be otherwise unburnt. If the EGR system is not in place the fuel would burn in the catalytic converter, possibly shortening the life of the cat.

Ryan

 

[dcdyd]

THanks all for the help and information. I did two things last night.

1) Replaced front O2 sensor at the driver side and cleared code. Drove about 15 miles and no engine check light. I will continue to mnitor it.
2) I finally found the hole on the cranckase and puched replaced PCV valve in. I will do seaform later this weekend. It was hard to get in there although I don't have a big hand and big arm. It was a strech for me and only had very limited space for all the work. I wonder how a person with big hand and big arm can do this task.

 

[Handegard]

Thank you all for the answers. I will replace the OS2 on Bank2 upstream and I will try to check and replace the PCV valve.

I still don't understand one thing. If the PCV valve has not been on where it should be for a month and the truck ran well. Then what it is used for? I somehow understand that it is used to recycle the unburned fuel (?) back to the engine. But if it is not connected, what does the engine do about those unburned fuel if my understandng is true.

Prior to pcv valves, the fumes were just vented to the atmosphere. When the valve is unhooked, it is just venting instead of re burning the fumes.

Oops, I see now this has been covered.. Anyway....