What Is This Hose?

DSN46 · October 31, 2009

Hey All,

Having a shuddering-idle problem (like alot of others!)

5.3 ltr on a 2004 Suburban. It has the electronic throttle (no cable).

I was looking closely trying to find any cracked hoses, etc. when I noticed a black hose that is supposed to attach to the passanger's side of the throttle body. It has suction on it when engine is running and it runs down to the valve cover.

It is supposed to slip over a black plastic nipple coming off the throttle body, but the idiot who owned it before me must have snapped the nipple off!

Can anyone tell me WHAT this hose is for (a modified EGR maybe?) And is it REALLY important? I don't think I can replace the broken off nipple, it looks molded to the intake itself.

Thanks for any and all advice or answers!

James

dlstewart01 · October 31, 2009

I believe thats the fresh air supply for the block. Don't think you have EGR, The PVC is on the drivers side valve cover and goes to the middle of the intake.

DSN46 · November 2, 2009

Thank you for your reply!

What you say makes sense. It comes off the throttle body AFTER the butterfly so it would be sucking filtered air down into the block...

I hope that is all it is. I can come up with a way to make it work so-so.... I just hope it isnt anything MORE important that is costing me MPG's or harming my engine.

Anyone else have a guess?

James

Prokopchuk_9 · November 2, 2009

Thank you for your reply!

What you say makes sense. It comes off the throttle body AFTER the butterfly so it would be sucking filtered air down into the block...

I hope that is all it is. I can come up with a way to make it work so-so.... I just hope it isnt anything MORE important that is costing me MPG's or harming my engine.

Anyone else have a guess?

James

check and see if ur PVC valve rattles if it doesnt get a new one

frdfandc · November 2, 2009

That is not a fresh air supply. That is part of the PCV system. When the engine is running, its pulling oil/burnt exhaust fumes out of the crankcase and injecting them back into the intake to be reburned in the combustion chamber.

Helps with emissions. It needs to be fixed and routed correctly.

MS3DALE · November 2, 2009

check and see if ur PVC valve rattles if it doesn't get a new one

Actually the PCV valve shouldn't rattle,Its a "fixed orifice" PCV system and doesn't have any moving parts in it.

dlstewart01 · November 2, 2009

That is not a fresh air supply. That is part of the PCV system. When the engine is running, its pulling oil/burnt exhaust fumes out of the crankcase and injecting them back into the intake to be reburned in the combustion chamber.

Helps with emissions. It needs to be fixed and routed correctly.

There is a fresh air supply hose. I believe it is right after the throttle body on the passenger side. This is probably part of the PVC system but is a throttle body vent tube and there are no crank case fumes passing through it. The PVC is on the drivers side and goes to the intake about half way down. The trucks are different from the cars. The PVC is a fixed orifice and as MS3DALE said, it has no moving parts.

When I hooked up my catch can between the PVC and the intake I did some research on this. My factory manual says this is a fresh air supply and fresh air only goes through it.

txab · November 2, 2009

That is not a fresh air supply. That is part of the PCV system. When the engine is running, its pulling oil/burnt exhaust fumes out of the crankcase and injecting them back into the intake to be reburned in the combustion chamber.

Helps with emissions. It needs to be fixed and routed correctly.

There is a fresh air supply hose. I believe it is right after the throttle body on the passenger side. This is probably part of the PVC system but is a throttle body vent tube and there are no crank case fumes passing through it. The PVC is on the drivers side and goes to the intake about half way down. The trucks are different from the cars. The PVC is a fixed orifice and as MS3DALE said, it has no moving parts.

When I hooked up my catch can between the PVC and the intake I did some research on this. My factory manual says this is a fresh air supply and fresh air only goes through it.

+1

There is no vacuum into the intake at this port. There is vacuum into the valve cover. Since there is a fixed orfice or a PCV valve on older models, air that is drawn from the engine through those ports has to be replaced with air from somewhere. I believe that's the purpose of this tube/port in question. It does need to be repaired so that only clean air and nothing else can be ingested into the valve cover.

DSN46 · November 2, 2009

You guys Rock!!

Thank you for explaining that to me. I knew it wasnt PCV because I know what that is... I just couldnt figure out what the passanger side hose was.

Thank you again.

James

Spurshot · November 2, 2009

That is not a fresh air supply. That is part of the PCV system. When the engine is running, its pulling oil/burnt exhaust fumes out of the crankcase and injecting them back into the intake to be reburned in the combustion chamber.

Helps with emissions. It needs to be fixed and routed correctly.

There is a fresh air supply hose. I believe it is right after the throttle body on the passenger side. This is probably part of the PVC system but is a throttle body vent tube and there are no crank case fumes passing through it. The PVC is on the drivers side and goes to the intake about half way down. The trucks are different from the cars. The PVC is a fixed orifice and as MS3DALE said, it has no moving parts.

When I hooked up my catch can between the PVC and the intake I did some research on this. My factory manual says this is a fresh air supply and fresh air only goes through it.

I just had my 99 2500 6.0L throttle body off for cleaning and it had a hose that went to a port with a valve that openned and closed. I believe it's part of the emission reduction system to allow air into the manifold when the throttle is closed during deceleration. We used to call these systems "gulp valves". The valve opens when the throttle is quickly closed and the rpm is still up. This device is the reason my truck feels like you really didn't let off the accelerator completely for a few seconds.

DSN46 · November 2, 2009

Okay,

Took it to dealer (mechanic is a friend) this morning. He said it is a Fresh Air intake for the crankcase. It takes filtered air from intake for the crank case. (I think that is what he said).

He said to try to cut what is left of the nipple off the intake (it is molded plastic onto the side of intake) and then tap a brass nipple into the hole. If that doesnt work, then he said an intake replacement is in order.

Anyone have any advice for tapping the hole with a brass nipple from hardware store?

Thank you again,

James

dlstewart01 · November 2, 2009

Okay,

Took it to dealer (mechanic is a friend) this morning. He said it is a Fresh Air intake for the crankcase. It takes filtered air from intake for the crank case. (I think that is what he said).

He said to try to cut what is left of the nipple off the intake (it is molded plastic onto the side of intake) and then tap a brass nipple into the hole. If that doesnt work, then he said an intake replacement is in order.

Anyone have any advice for tapping the hole with a brass nipple from hardware store?

Thank you again,

James

Now why didn't some of you guys want to believe the old geezer????

txab · November 2, 2009

Okay,

Took it to dealer (mechanic is a friend) this morning. He said it is a Fresh Air intake for the crankcase. It takes filtered air from intake for the crank case. (I think that is what he said).

He said to try to cut what is left of the nipple off the intake (it is molded plastic onto the side of intake) and then tap a brass nipple into the hole. If that doesnt work, then he said an intake replacement is in order.

Anyone have any advice for tapping the hole with a brass nipple from hardware store?

Thank you again,

James

You could drill out the hole to fit the nipple, then epoxy it in there.

DSN46 · November 2, 2009

I managed to Dremmel off the hard angles and shape what was left into a sort of shortened version of a nipple. Just enought that I was able to push the hose on and use a small hose clamp to cinch it on there. It has stayed well so far and it is air-tight. Hopefully it will hold and I wont have to resort to more drastic measures.

Thank you again,

James