I have deleted a/c, egr and smog pump. Not sure what this is for, if it is for one of those systems can I just cut and cap it?

 

Air system for cat converter.

 

I don't have any cats. What does the metal line go up to?

 

It used to go from the AIR Pump down the catalytic converter. Just take it out, you don't need it if you don't have AIR or a cat.

 

Can I just leave it open or cap it somehow without welding it?

 

Follow it, cut it, and pinch it if necessary.

 

Ahhh crimp it shut, that's perfect.

 

Just take it out. It's not connected to anything at either end if you have removed both the AIR pump and the catalytic converter.

 

 

Is it something that needs to be plugged?

 

No. Because it's not connected to anything at either end because you said your car does not have a smog pump and you said your car does not have cats. If it's still connected to something, then I am misunderstanding, so please post more pics. The pipe you are asking about is item #47 in the first illustration and connects to smog (AIR) pump via items 50, 51, 41, 27 and 38 in that same first illustration. The other end connects to your cats via either 16 of the second illustration (if you had dual cats, which is what it looks like in your pic) or 24 of the third illustration if you had a single cat. All that pipe did was to deliver fresh air to the cats from the smog (AIR) pump. It is just an unused hose now. What is left in your car that you are asking about pinching off and I think I can better answer your question? Either use the callout #s in the illustrations I posted or take a pic on your car and I'll be glad to answer what it is.

 

I have no cats, just straight pipe. That metal line goes into the exhaust tube just after where the headers merge into the one 3" pipe. I'm just curious because exhaust will be passing past that hole, if that will cause any problems?

 

You need to provide us with more details up front when you ask these questions. 11 posts going back and forth, because we all thought this was a fairly unhacked car, and we were looking at stock features.

Looking closer at the first picture, taking your latest picture and information into account, it is clear that this is an aftermarket, custom modification to provide external EGR from the exhaust Y pipe up to the intake manifold.

A good start is to follow the part and see where it is connected. In this case, the answers would appear to be: 1) the exhaust tube below the passenger side manifold, and 2) the rear of the intake manifold.
Then we can tell you: this is external source for EGR.
Then the next question for you is: what are your plans for the car? Keeping the exhaust or installing headers? Keeping or changing intake manifold? Keeping or removing EGR?
Then we can make recommendations to you as what you should do with your external EGR supply.

 

I have deleted EGR, I already had headers but they had tubes welded into the top of them for AIR so I bought new ones without. Have an edelbrock high flow intake.