Our pcv valves are located in the oil filler neck and run to the back of the intake manifold. For some reason when I had the 08' intake installed, the installer just left the tube from the pcv off and it vents into the open air of my engine bay. I have a feeling this isnt correct and it may be a reason why my A/F is so f*cked on my turbo Dak right now. Whats the proper way to hook this up in a turbo application?

 

The PCV can also be located on the back leftside of the truck too As far as the turbo setup, I can't really say...

 

why dont u route it like it was originally. Put back the hose your mechanic remved

 

leave it out with a breather

 

That is incorrect. If the crank case vents to the atmosphere, it has nothing to do with a/f ratio. But, I want to make sure I'm understanding what you are trying to say. Does the new 08' intake have hose that vents to the atmosphere, or is the crankcase venting to the atmosphere?

So, there are three ways you can run crank case ventilation

1.) Run in to a catch can that is vented.
2.) Run it to the intake (between the air filter and turbo compressor section, NOT AFTER THE COMPRESSOR SECTION).
3.) Run it to a sealed catch can, and run from the can to the intake, (between the air filter and turbo compressor section, NOT AFTER THE COMPRESSOR SECTION).


Let me very clear about this...DO NOT RUN THE CRANK CASE VENT HOSE TO AN ORFICE AFTER THE COMPRESSOR HOUSING.

So, what is the difference between all three? Running a vented catch can eliminates any oil going into the intake (even the best sealed catch cans dont catch everything and still flow enough). The problem with this is, you are with out a vacuum source to aid in the ventilation. Does this cause a major issue? Not if your lines are big enough.

Running directly to the intake (sans catch can) will be a wonderfully oil'ly experience. You will see oil in the intake, compressor wheel, IC piping, throttle body, etc. Since you are a remote mount configuration, the chances of oil coating everything is slim. The enormous length of IC piping will hold most of the residual oil anyway.

Ah, running a sealed, baffled catch can is the best thing for a street car. This way, you catch the oil, have a vacuum source aiding in the ventilation, and you don't smell the oil saturated air from underneath the hood like you would with a vented setup. However, there is a downside. Like option two, you will still see hot air flowing into the intake. Obviously, the colder the charge of air, the more power the engine makes. Adding hot air doesn't help with this.

So, take your pick from the three. All of them work. On the race car, I run a vented catch can with a -10 and a -6 line. But then again, I run 27psi. Completely different from the amount of crank case air flow you will ever see. My suggestion is, run a sealed, baffled catch can.

 

My basic understanding of the pcv system is it consists of three parts; the valve itself, a fresh air inlet house which usually connects beteen the filtered air intake before the TB and two breather pipes at the back corner of either valve covers, and the crank case ventilation hose that connects the valve to the intake manifold. On the 05 intake before I did any fabbing, the crank case house connected the pvc valve to a port on the rear of the intake mani and the fresh air hose connected into my cai. With the 08 manifold and the turbo, both those lines connect to nothing now and just vent into the atmosphere. I'm primarily worried that my PCM is used to seeing this sytem functioning properly and when it sees that it isnt, it tries correcting the issue which was making my truck run extremely rich. If your saying this has no effect on a/f ratio then obviously my problem lies elsewhere. On a different note, what kind of vacuum should our trucks be seeing at idle, I sit around -20psi, normal?!

 

this is what it looks like now....Ill look into the baffled catch can, Thank you

 

At idle, you should be between -20 and -26inHg when you first let off after a pull, it will be as low as -30.

 

Remme, perform a boost leak test. The crankcase venting has nothing to do with a/f ratios. This will tell you if the ECU is seeing inaccurate airflow, thus causing the wacky a/f ratios. Do you know how to do this?

 

Let's get some things straight here. There's a breather side and a PCV side. The PCV side going from the intake manifold to the valve cover should always be left hooked up. It sounds like your breather side is vented to the atmosphere, which is fine but you should use a filter on it. Regardless this has nothing to do with your AFRs, I'd suspect that lies in your tuning method somewhere. Also you should run a check valve between the PCV and intake manifold, as PCV's are not very good check valves under boost and you don't want to be pushing boost pressure into the crank case.

Donkeypunch also suggested some good ideas, such as running a catch can and/or running the PCV side to between the filter and compressor inlet, that will insure a vacuum draw on the crank case under boost.

How are you tuning the truck? SCT (Hemifever?), he tunes notoriously rich.