grantv

At cold start, a small electric motor by the DS front wheel injects fresh air (drawn from a hose from air filter housing) into exhaust manifolds. Helps with cold start emissions only (gets cats up to temp quicker where they are most effective); once warm the system does not run.
The path...
-Fresh air from air filter housing into air pump
-Single hose from pump gets divided into 2 by steering column
-Hoses feed into exhaust manifolds with one way check valves to ensure no reverse air flow
Earlier renditions of this were a belt driven smog pump that did a similar job.

Bill Curlee

The A.I R. System does occasionally run during steady state part throttle conditions. It is commanded on by the PCM to test the A.I.R. System and to see if the O2 sensors and CATs are working properly. When the A.I.R. pump is commanded ON the PCM expects to see the O2 sensor outputs to go lean a specific amount and the after the CAT O2 sensors to stay at a specific reading.

Bill

bravo29

On my 2k Trans am I had this issue. AIR was removed (headers and Slp loudmouth) still had the pops. They were not gone until I got it tuned. Once I got it tuned all the pops were gone. I like hearing the pops sometimes.