WHERE/WHEN Does the smog pump/valve send air?
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Joined: Nov 2005
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From: Sacramento
Car: 91 RS
Engine: 350 TBI
Transmission: WC T5
Axle/Gears: 3.42 Posi
WHERE/WHEN Does the smog pump/valve send air?
You've got 3 options....atmosphere, manifolds, and cat. From the factory, where is air being sent under what conditions?
Joined: Mar 2000
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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
Open loop - manifolds.
Most closed loop conditions - cat.
Some closed loop conditions (deceleration, I understand) - manifolds.
Most closed loop conditions - cat.
Some closed loop conditions (deceleration, I understand) - manifolds.
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From: Orange, SoCal
Car: 1990 Pontiac Trans Am
Engine: 355 TPI siamesed runners
Transmission: Tremec T56
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Re: WHERE/WHEN Does the smog pump/valve send air?
That seems backwards to me. I would think at open loop the air went to the cat to heat it up quicker.
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From: Mercedes Norte, Heredia, Costa Rica
Car: 1984 Z28 Hardtop
Engine: 383 Carb
Transmission: 4L60
Axle/Gears: 3.54 Dana 44
Re: WHERE/WHEN Does the smog pump/valve send air?
In open loop it goes to the manifolds for better mixing, better burning of leftover hydrocarbons, and because the ECM is ignoring the O2 sensor anyway.
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
A.I.R. existed before 1975, when catalytic converters became mandatory. It always went to the manifolds, right at the exhaust port exit. That's where the exhaust gases are hottest, and the reaction is most effective (other than the cat, that is).
We used to have a full-size '84 Chevy van, which did have a cat. It had an open-loop q-jet, so no O2, and the A.I.R. only went to the manifolds - no tube to the cat.
We used to have a full-size '84 Chevy van, which did have a cat. It had an open-loop q-jet, so no O2, and the A.I.R. only went to the manifolds - no tube to the cat.
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