420A 2GNT Plugging Valve Cover Port fixes idle?

[Reject]

97 Eagle Talon 2.0 NT

Curiousity;

I had a little bit of a rough idle after I installed the cold air intake. It wasn't enough to warant worry, but it was annoying... so after a full tune-up, spark plugs, wires, fuel filter, pcv valve, etc I noticed that it was still there...

After playing around and replacing misc vacuum hoses I noticed that if I plugged the port that is on the valve over that the idle is instantly smooth again. Now I know the stock intake had a hose going to that port, so I am wondering is this the sign of a different issue?

I was curious about this and decided to put a breather filter on there to see what happened and plug the port in the CAI and it got really rough idle. Plugged it all up again and it idles fine...

Ideas? I'm lost...

 

[DSM4me44]

It sounds like you are capping the port that relieves the engine of crankcase pressure.

You do not want to cap that up.

Your rough idle is caused by something else. Capping that could damage some tihngs.

 

[Reject]

I am not capping the PCV port that drops into the intake manifold, but the other port that is to the drivers side of the valve cover that runs into the air duct, pre-throttle body...

 

[need2boostpsi]

did you replace your pcv valve? it may be sticking and pulling in air through the VC breather.

 

[Reject]

PCV brand new...
Less than 100 miles old...
Tubing to and from brand new with new clamps...

 

[->PrOjEcTGS<-]

Probably leaks... I would replace it again... The aftermarket units are notoriously known to go bad in a quickness.

 

[knochgoon24]

So wait, do you have the hose from the stock intake pipe to the valve cover? It is supposed to pull a vacuum through that port when the car is idling. It helps clear out the vapors from the head. That hose lets the fresh metered air in. The hose on the back of the valve cover to the intake manifold (with the PCV valve) is the side that sucks the vapors out. If you don't have the hose from the intake to the side port attached, you'll be inducing unmetered air.

Why do NTs even have a PCV valve? Wouldn't that port always see vacuum (or zero vacuum).

 

[jrohner]

Eliminate the PCV valve. Just run both lines from the valve cover to a breather box of some kind, or let them hang with a loop toward the top of each one til you get one.

 

[Reject]

That hose lets the fresh metered air in. The hose on the back of the valve cover to the intake manifold (with the PCV valve) is the side that sucks the vapors out. If you don't have the hose from the intake to the side port attached, you'll be inducing unmetered air.

Maybe a dumb question, knochgoon24, but how is the air sucked in from the "intake" side of the VC metered? The only thing that was there on the stock setup was a vacuum hose. There was no valve or control device...

So, I would imagine, just running a filter to the end of the port would allow it to pull as much air as it needed. But again, having said that, when I do that it idles like crap.

Eliminate the PCV valve. Just run both lines from the valve cover to a breather box of some kind, or let them hang with a loop toward the top of each one til you get one.

jrohner, I assumed that I could do the same thing as well, but then again I have the strange idle when I have flowing air through the system... I agree that that "Should" be acceptable and should not cause any adverse effects, but it does...

 

[1SickAuto]

on aftermarket intakes there should be a nipple on the intake tube itself, which connectes to the nipple on the VC. what kind of intake is it

 

[Reject]

A home depot special...

But again, if I simply put a breather filter on that nipple, it should be able to pull what ever air it wants, correct?

The assumption is that the PCV is the limiting factor that controls the vacuum caused by air getting sucked into the cylinders from the intake plenum right?

Worse case senario I can try hooking up the stock air box again and see if I get the same issue I guess... I am just not seeing why there would be a difference between the two...

 

[1SickAuto]

haha i see (poor boy racing mod) . my neon never had that nipple hooked up either, i just put a little filter on my, but then again i never had idle issues.

 

[Reject]

I think we have things backwards...

My idleing gets BETTER when that port is blocked off...

It's horrible when I have free flowing air to it...

I was wondering if this could be a sign of other problems...

 

[1SickAuto]

anythings possible man

 

[knochgoon24]

Maybe a dumb question, knochgoon24, but how is the air sucked in from the "intake" side of the VC metered? The only thing that was there on the stock setup was a vacuum hose. There was no valve or control device...

So, I would imagine, just running a filter to the end of the port would allow it to pull as much air as it needed. But again, having said that, when I do that it idles like crap.



jrohner, I assumed that I could do the same thing as well, but then again I have the strange idle when I have flowing air through the system... I agree that that "Should" be acceptable and should not cause any adverse effects, but it does...

Wait, 97 N/T with a 420a.... nevermind. I know next to nothing about that engine. For some reason I was thinking 4g63 N/T. My sister has an N/T Eclipse but never lets me touch it so I'm no help.