My '91 3.1 has an AIR pump (California) that injects air into the passenger side ex manifold. As the air is being injected ahead of the O2 sensor (after the Y) does this not adversely affect the ecu control of AFR etc.? Is air injected all the time? Later systems I believe inject the air into the cat (after the O2 sensor) which makes more sense to me but the cat injection tube is sealed off. Anyone know if the air injection could be re-rerouted to the cat or would that fail a smog test (if noticed)?

 

California car + Living in California = don't mess with the emissions system.

 

In closed-loop AIR is injected into the cat, not the manifold.

 

My cat is capped off which seems to be standard. The only injection I see is into the manifold. In any case, at normal operating temp the air should not be injected into the manifold?

 

From the factory it wasn't capped off. In any case, in closed loop air isn't blown in above the O2 sensor.

 

Actually the factory cat doesn't have an air tube. On the 3.1l f-body's the AIR only goes to the exhaust manifold, and only at one location. On the passenger side near where the manifold goes down to the Y pipe.

RBob.

 

Ah, that's interesting. Hardly seems like the system is worth the effort then.

 

hence why most of us dont have it anymore

 

Except in CA where I think you may be executed if you even look at it funny! Not LOL.