Okay, I snapped a hard plastic vacuum line a while ago, and replaced it with a rubber piece for the time being. It connected the TB vacuum lines to the lines by the EGR solenoid. It was a good connection to the TB, and a "poorly shoved on" connection by the EGR.

I noticed it fell off by the EGR system. I couldn't hear any vacuum hiss under the hood with the motor running. I also didn't feel any vacuum when I placed my finger over the hole.

Vacuum comes from the intake manifold, right? It doesn't come at all from the TB lines? How is this possible that I would have an open vacuum hose, but no "sucking" noise/feel? Think I have a leak elsewhere, or a clogged line?


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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
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Ported vacuum probably...

Not all vacuum connections are equal. For specialized connections, they will often drill a port into the throttle bore above where the throttle blades rest at idle; that way there's only vacuum available at conditions above idle. Vacuum advance for ditributors is like that. EGR usually is hooked up that way too, when it's not controlled by a solenoid.

Try opening the throttle a little and see if you get vacuum.

Vacuum sucks, doesn't it?

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"So many Mustangs, so little time..."

if its the vac. port im thinking of, your car shouldnt idle (as well) at least with it open. or, mine doesnt. is it clogged maby inside? i havent the foggiest of how it would be, but engines do very strange things sometimes... so does the idle change when its open/shut? or maby i dont undersand quite right...

I'm with RB83L69 on this one.

Should be ported vac. to the EGR solenoid.

Should have vac. off idle.


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ASE Mechanic/Machinist/Smog Tech

1999 NBM Trans Am
1986 Chevy 3/4 ton pick up
1981 corvette
1995 Kawi ZX6R

GO #3

Thanks guys! (Well, except for that pun, RB! ) I'll give that a try (raise idle, look for vacuum). I picked up a set of vacuum lines out of a junkyard, and even managed to copy the emissions label so now I have a vacuum line diagram.

I still don't believe my Helms book has no vacuum diagrams in it! Can't I buy that underhood emissions label from the dealer?


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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!