I'm rebuilding my 88 GTA 5.7 TPI and have re-installed the intake manifold, the fuel rail and the plenum. There are 3 holes that I can't find in my diagrams:

1) In the middle of the bottom of the plenum (near the fuel pressure regulator)

2) In the rear driver's corner of the plenum

3) In the intake manifold above the cold start valve.

I think I messed up by connecting the MAT sensor in hole number (1) and the brake vacuum booster in hole number (2).

Is this right?

I found one picture of the cold start valve with what looks to be a vacuum line connection in hole number (3).

I removed the EGR valve and blocked the hole so if one of these is for an EGR-related item, I probably don't need it.

Can anyone help?

Thanks!

Also, I removed the AIR pump and piping (intalled new Hooker headers) and am having difficulty routing the vacuum lines. If anyone has a diagram for the vacuum (and electrical) lines for a TPI without an EGR or AIR system, I would greatly appreciate it.

Lastly, is there any benefit to intalling a throttle body bypass and/or air foil on a L98 TPI?

Thanks!

 

You hooked it up right. That other hole is an EGR passage. Might as well leave it.
A diagram without those two systems would have to be made. What issues are you having?

Lastly, definitely yes and debatable but probably.