LG4 Vacuum Help
Thread Starter
Junior Member
Joined: Apr 2003
Posts: 20
Likes: 0
From: Huxley, Iowa
Car: 1986 IROC Camaro
Engine: LB9
Transmission: 700r4
LG4 Vacuum Help
Ok guys I've done a search and have not found the info that im looking for yet. I just finished rebuilding the LG4 in my 82 Z that i bought. The previous owner took out the air pump etc, and I think he took more than he was supposed to. I'm looking at a vacuum diagram that i got off of this board and i cant figure out how the egr vacuum is supposed to be run. Also how the Evap canister lines hook up. Any pictures you have would be great. I know that the way it was when i bought it was not right because it had horrible vacuum leaks. Thanks for your help.
Last edited by Fast_Fitz; Apr 11, 2004 at 10:31 AM.
There should be a VECI label and vacuum routing diagram label affixed to the underside of the hood. How does the vacuum routing compare to that?
Presuming that you may no longer have the labels, and you are following a diagram you found here, what diagram is it? It may not be correct for your engine. Since you're in IA, I'm guessing that you have a domestic LG4, not an export car, correct?
Presuming that you may no longer have the labels, and you are following a diagram you found here, what diagram is it? It may not be correct for your engine. Since you're in IA, I'm guessing that you have a domestic LG4, not an export car, correct?
Thread Starter
Junior Member
Joined: Apr 2003
Posts: 20
Likes: 0
From: Huxley, Iowa
Car: 1986 IROC Camaro
Engine: LB9
Transmission: 700r4
There is not a sticker anywhere anymore. The guy that had it before me hacked it up pretty good. I checked my GM service manual but didnt really find anything. The diagram that was in the Chilton Manual appears to be for a Canadian non CC setup.I was using a diagram that RB posted i believe. Yes the car is domestic.
Here is the diagram
Here is the diagram
Supreme Member

Joined: Jul 2001
Posts: 3,974
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From: Pueblo Co
Car: 1989 C4
Engine: L98
Transmission: 700r4
Axle/Gears: 307
Yes that is the correct diagram for a 4bbl CCC system. Just finished hooking one up myself so I can voutch for it except where it says vac sensore it really means MAP.
Thread Starter
Junior Member
Joined: Apr 2003
Posts: 20
Likes: 0
From: Huxley, Iowa
Car: 1986 IROC Camaro
Engine: LB9
Transmission: 700r4
Do you guys possibly have any pics of the canister control valve? I cant seem to find anything like that and its starting to make me think that im missing it (wouldnt be the first thing missing on this car). Thanks for your help guys.
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Joined: Mar 2000
Posts: 43,187
Likes: 42
From: Littleton, CO USA
Car: 82 Berlinetta/57 Bel Air
Engine: L92/LQ4 (both w/4" stroke)
Transmission: 4L80E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
Thread Starter
Junior Member
Joined: Apr 2003
Posts: 20
Likes: 0
From: Huxley, Iowa
Car: 1986 IROC Camaro
Engine: LB9
Transmission: 700r4
Thanks guys, I didnt have one of those so that clears up some of it. Another question I have is what is the part in the picture I'm attaching. It looks like vacuum lines hook up to it but I'm not sure since nothing was hooked to it when I got the car.
The Part
The Part
Joined: Mar 2000
Posts: 43,187
Likes: 42
From: Littleton, CO USA
Car: 82 Berlinetta/57 Bel Air
Engine: L92/LQ4 (both w/4" stroke)
Transmission: 4L80E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
That's a thermal/vacuum switch. I'm not sure which one, but it should have the type molded on the top (like "EFE").
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