I got to thinking, with the air injecting into the exhaust manifolds, the O2 sensor should pick up the extra oxygen, but I'm sure our computers have already compensated for this.
Now, my pump is squilling, so I thought I'd take off the belt, but got to thinking that the computer wont see the extra air, and think its running rich, therefore, lean me out.
What do you think?

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Rob
'86 TA 305 TPI
Gutted MAF, Ported Plenum
TB Bypass, Home made Cold Air Intake,
Edelbrock T.E.S.

 

Not a problem, yank it. The computer won't have any issues with this. The air injection is for smog purposes only, it dilutes the exhaust gases with extra air. During closed loop operation the air is diverted to the cat so the computer (O2 sensor) never sees it!! It sees the air only during warm-up or open loop.

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Phil87IROC
Blue '87 IROC, 383 Crate Motor, KB pistons, AFR 190 heads, ZZ-9 cam, Edelbrock RPM intake, Hooker SC/LT headers, Edelbrock 750 cfm Carb (#1411), stock T-5, GM 3.42 rear w/Auburn posi.
Ohio Valley Dragstrip Trophy Bracket WINNER - 8.39 ET on a 1.82 sec. - 60'. Best MPH = 84.44. Still Tuning Carb!
Red '89 IROC L98, 700R4, T-Tops, K&Ns w/open air boxes, 160 T-stat, Hyper Chip, gutted MAF, 53kv coil, MSD wires.

 

Air is only injected in the manifolds when the car is stone cold. When it warms up a valve switches the airflow to the cat.

 

I understand the purpose of injecting the air into the cat to help it perform its job, but why the manifolds? And why only when its cold?

 

Because when it's cold the cat isn't doing it's job yet. Adding air right where the flame comes out of the head adds more oxygen and continues the 'burn' thus decreasing emmisions and helping light off the converter even faster.