Hellow,
I have SE 86 2.8 L, could any one please tell me what is the large pipe that connects to the middle of the intake manifold, on the right side, see image

Another question, acoording to the vacuum connection layout. this connector just going to the fire wall for fresh air, could it be eliminated?

The big connector is for the brake booster, none of those vacuum lines on the intake go to the firewall for "fresh air" I think that one goes to the EGR solenoid, there are 2 on the throttle body that go to the trunk wall for the evap system, and cruise control, all others are for the fuel pressure regulator, map sensor, EGR system, etc.

quote Originally posted by itzikbns: Another question, acoording to the vacuum connection layout. this connector just going to the fire wall for fresh air, could it be eliminated?

This one routes underneath the upper intake and around past the MAP sensor and goes into a dual rubber connector. It briefly converts to a rubber hose that connects to the hard metal lines on the trunk wall that route over to the EVAP canister.

quote Originally posted by 1985 Fiero GT: The big connector is for the brake booster, none of those vacuum lines on the intake go to the firewall for "fresh air" I think that one goes to the EGR solenoid, there are 2 on the throttle body that go to the trunk wall for the evap system, and cruise control, all others are for the fuel pressure regulator, map sensor, EGR system, etc.

Thanks for replying, could you please elaborate a little regarding the role with the brake booster? is it a vacuum? etc.

quote Originally posted by itzikbns: Thanks for replying, could you please elaborate a little regarding the role with the brake booster? is it a vacuum? etc.

That is the vacuum source for the brake booster. connects via a rubber house to the firewall hard line.

Your first photo is the vacuum port for the brake booster line as jelly2m8 said.
Your second photo is the vacuum port for the fuel canister line as fierofool said.

I edited the GM vacuum diagram as a complete drawing.....


BTW - I prefer printed manuals but you can get Digital Fiero Manuals from the Internet
https://fieroinfo.com/manuals/


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Original Owner of a Silver '88 GT
Under 'Production Refurbishment' @ 136k Miles

[This message has been edited by Vintage-Nut (edited 07-25-2024).]