C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Plenum Vacuum Lines help..

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Old Sep 29, 2022 | 10:12 AM
  #21  
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Originally Posted by IHBD
The ? connects to the EGR solenoid.
The other EGR solenoid connects to the bottom of the throttle body. (NOT the plenum.)

#3 on the plenum connects to #1 on the check valve.

#2 and #3 on the check valve are the same. One goes to the HVAC which is a hard line that is in the wire harness. The other goes to the cruise control and vacuum ball. (There's a T for the branch to the vacuum ball.)

The EGR system does not get its vacuum from the plenum. EGR vacuum comes from the bottom of the throttle body.

The EGR Solenoid has 2 outlets, one to the TB and one to the EGR Valve right?
so where does the check valve connects?


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Old Sep 29, 2022 | 12:07 PM
  #22  
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This what I have:


Does that make any sense?
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Old Sep 29, 2022 | 01:10 PM
  #23  
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That’s what I was trying to figure out… thank you. The connection I have is wrong… I’m sorry for being confused but it’s all missed up there… and I guess I need to re do the whole thing.

so from your post and post #10, the re-routing will be as follow:

- The EGR solenoid’s 2 outlets are connected to the TB and the EGR Valve (no check valve there).

- The check valve should be connected to #3 on the plenum which will connects to HVAC, cruise control and vacuum tank.

Does that sound right?

and if anyone can share the 91’ diagram in FSM or page number?

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Old Sep 29, 2022 | 01:37 PM
  #24  
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Great thanks a lot man… that was
helpfull
i’ll try and do it all over as mentioned.

as for the label of the routing it’s not there I guess it was faded/removed… as the radiator cover is replaced..

will update once work is done.
The again
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Old Sep 29, 2022 | 09:57 PM
  #25  
arbee's Avatar
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This routing decal is readily available from several sources with a google search.
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