I'm putting an after market air intake system on my 88 2.8. There is a connection for the sensor, 1/4" little air tube, but I'm not sure if I should plug the big 1" tube that comes off the metal tube along the back of the engine, or put a little air filter on it.
Somebody said it doesn't do anything anyway...that does not make sense to me...it must do somthing...So...Plug it? Filter it? What is it?
Thanks.

That large tube connected the valve cover to the air filter housing (clean side of the filter) to supply clean air into the engine for the PCV system. The recall removed the rubber hose connecting that tube to the valve cover and replaced it with a steel tube assembly that connected the valve cover to the intake snorkel right next to the throttle body. The recall kit included a rubber cap to cover the end of the tube where the old hose was. Since that tube was connected to the clean side of the filter housing it means that any air going into it bypasses the filter and goes straight to the motor. Those caps get lost over time, and often people will put a cap on the nipple at the air filter housing that connects to the other end of that tube, thereby removing the tube entirely from the engine intake air stream.

There's no need to put a filter on it, either a cap on it or on the filter housing will do the job.

JazzMan

EDIT james beat me to it while i was writing this. but i spent the time to track down a pic so i'm leaving it here.

that after market air system is probably going to make a lot of noise.
but to answer your question....
asuming we are talking about this...


the big pipe and small pipe on the firewall are attached to each other.
GM did a change to the breather piping.
i've seen vairous stages, but i've never seen the actuall paperwork for the recall so i dont know what is "correct".

the right side of the big pipe should not be connected to the engine
the left side of the big pipe should not be connected to the air intake system
there is no need to cap it off.

[This message has been edited by buddycraigg (edited 02-29-2008).]

Thanks Jazzman and Buddy. My after market intake will still go all the way down to the cold air intake outlet to get it's air.
Yes that is the pipe I am talking about. I can't see where the engine side goes...I'll have to look harder to see if it is attached to the engine and where. The filter side is obveous to see.
So If I have got this right....
1. If it is attached at the engine for the PVC system then cap off the filter side so no unclean air gets into the system..and there is no reason for it to have a filter on it.
2. If it is not attached at the engine side, obveouslly I will not have to cap it off at the filter side.
3. If it is not attached at the engine side, should I cap off where it use to go in?
I must sound like a nimrod on this but I'm kind of confused. Sorry.
Thanks Buddy and JAZZMAN.

BTW: Some may say you dont need it, but don't do away with that sensor. It's the MAT 'Mas Air Temp - Mean Air Temp - whatever it is called, it tells the ECU how hot or cold it is ouside and thus affects your fuel mix. I had one go bad and had I not had our wideband on the car at the time I would not have believed it could do what it did to the idle. One sec it told the engine it as like zero and then 110 etc the dile was all over the place as the fuel keep changing. We thought we had burned a bad chip but it was the MAT. I check it with an ohm meter and sure enogh it was bad. New MAT, nice idle. So find spot for it.

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DO NOT PLUG IT!!!! Plugged PCV is bad idea. Here is a pic of what I did. I did not want a breather right on the end that would vent PCV over the motor under the sealed hood. Possible fire hazard. So I bought 5/8" (IIRC) tubing, rammed it into the line, ran it out to under the vent and put a Spectre breather from pep boys on it. Whole deal was like $11. It is black tubing now, the green was temporary free tubing to test the idea and it makes it easier to show people when they ask these kinds of questions.

quote Originally posted by Highjumper: 1. If it is attached at the engine for the PVC system then cap off the filter side so no unclean air gets into the system..and there is no reason for it to have a filter on it. 2. If it is not attached at the engine side, obveouslly I will not have to cap it off at the filter side. 3. If it is not attached at the engine side, should I cap off where it use to go in? I must sound like a nimrod on this but I'm kind of confused. Sorry. Thanks Buddy and JAZZMAN.

it is very unlikely that it will be attached at the engine,
but there could be a S shaped hose on it that is tucked away, or part of the hose could still be there, just cut off short.
or the hose could be completely gone with just the pipe there, or it could have a cap on it.

and since your new intake system doesn't use the factory air filter box, you dont need to put a cap on it.

It does go into the engine. From what I can see right into the bottom of the intake manifold. There is a elbow on the end of the large hose and it drops right into the engine. So dirt could get into the engine if it is not capped or filterd.

In the trunk side valve cover, there is a PCV valve in it, a 90* bend runs off it, it runs under the intake plenum, another 90* bend plugs it into the base of the intake plenum. I removed that and put a breather directly in the valve cover. The rear (cabin side) valve cover has the 1/2" tube that runs into the intake boot (non-vacuum side) I put a breather on that tube like in the above pics.

quote Originally posted by Highjumper: It does go into the engine. From what I can see right into the bottom of the intake manifold. There is a elbow on the end of the large hose and it drops right into the engine. So dirt could get into the engine if it is not capped or filterd.

something doesn't sound right.
if that hose was still attached to your engine the way the factory put it together, it would be attached to the left valve cover. not the intake manifold.

and if that hose was attached to your intake manifold, you would have a vacuum leak the size of a 1 inch hole. so your car would idle at about 7000 rpm.

there is a hose that comes from the firewall that attaches to the intake manifold.
it's the vacuum line for the brake booster.
that's a totally different metal pipe.

quote Originally posted by buddycraigg: something doesn't sound right. if that hose was still attached to your engine the way the factory put it together, it would be attached to the left valve cover. not the intake manifold. and if that hose was attached to your intake manifold, you would have a vacuum leak the size of a 1 inch hole. so your car would idle at about 7000 rpm. there is a hose that comes from the firewall that attaches to the intake manifold. it's the vacuum line for the brake booster. that's a totally different metal pipe.

Your right. It goes to the cabin side valve cover. It leaves the valve cover then goes to the metal pipe, then goes into the stock air cleaner canister. Sorry not the intake manifold.

mmm
then your car has NOT had that recall done.

if the recall had been done, it would be a metal pipe coming out of the left valve cover, about 2 inches.
makes a bend towards the drivers side and goes a little past the throttle body.
makes another bend and plugs into the big rubber tube that connects the air cleaner housing and the throttle body.

dont throw that big rubber tube away.
when a person swaps in an isuzu 5 speed and they have a V6 they need the "pre-recall" rubber tube to clear the shift cables.