On a MAF setup, if anything lets air bypass the MAF sensor the engine simply won't run right. The ductwork around the MAF is also important for it to measure airflow properly.

With the MAP system (older models), air leaks just make the engine idle high. You can do just about anything you want for a custom intake on those and it will still run OK.

Also don't trust your dash tach for the idle speed. If it were really only turning 200 rpm the car would be shaking like crazy because the engine would be very close to stalling if it doesn't actually stall.

 

Ok but there's one thing I still don't understand, if this PCV hose (the rubber one that usually goes from behind the valve cover to the intake) is sucking (vacuum), then how would air be flowing into the intake? I mean I understand the intake is a big vacuum, but hooking a sucking hose up to the sucking intake, how does that work?

 

As I mentioned earlier, filtered air moves from the air cleaner into the breather hose and the crankcase then out the PCV valve and PCV hose into the intake manifold. The system is designed to have strong vacuum at the intake manifold but not at the air cleaner so that air moves only in the desired direction.

 

I'm still a little confused. I believe I understand how the PCV system works. But, then how is this hose I'm talking about the pcv hose? The hose I am speaking of was not originally connected to the intake manifold (I accidentally said manifold in some of my original posts but I just meant the intake pipe or intake itself), it originally was connected to the intake itself. And if the pcv hose is the one that moves air from the crankcase, and this hose is not outputting air, but sucking air in from the intake manifold (toward the crankcase), then wouldn't this be a different hose?

To make sure I am being clear I drew a diagram, i know its not the best ;-)



Also here is a picture of the current setup along with my explanations:


Green: Sensor is actually connected now but wasn't in this picture
Red: Breather hose which is not connected
Orange: The hose I'm taking about, it sucks air in, is disconnected.
Blue: Isn't this the PCV valve and hose?

and finally the factory diagram:


I know by now that the disconnected hoses are causing the idling problem but I guess I'm trying to clarify my understanding of the system.

 

In your photograph:
1) The circled blue vacuum hose is connected to the fuel pressure regulator.
2) The circled red hose connector leads to the breather hose.
3) The circled orange hose connector leads to the fuel injector air (FIA) control system.

In photograph of my stock D16Y8 engine below:
1) Green = vacuum hose for fuel pressure regulator (see diagram)
2) Blue = breather hose
3) Yellow = FIA hose (see diagram)
4) Red = PCV hose

Therefore, your breather hose and FIA hose are disconnected. Are the ends of the disconnected hoses blocked off or are they drawing unfiltered air from the engine compartment?

 

They are drawing unfiltered air from the engine compartment. So would this still cause a problem? Yeah if the end of the FIA hose was blocked the engine would like kill pretty much, I put my finger over it momentarily a while ago, and the engine started to stall.

 

Okay, the two disconnected hoses per se are unlikely to cause the idle problem because the hoses are still able to draw air through each system. Still, drawing unfiltered air through the two hoses IS a problem by allowing destructive dirt, dust, and debris to enter the crankcase and fuel injector system.

 

Yeah, I'm gonna go get some plumbing fittings to hook those up to the intake.

 

Regarding the idle problem, try cleaning the IACV and adjusting the idle screw on the throttle body.