how much air does the pump move into the cat? is it measured in psi or vol/sec or what?

 

Don't know if the S4 airpumps are the same, but I can tell ya that mine puts out about 2-3 psi at 3,000 rpms...that help any?

 

when it puts air into the cat, it puts very little, the holes are TEENY. it puts most of the air into the exhaust ports

 

You talking about the port air system, j9fd3s? I thought that was de-energized after 20,000 miles...

 

ok, so the airpump builds 2-3psi at 3000rpms it must build more at 7000rpm's.

 

ok, so the airpump builds 2-3psi at 3000rpms it must build more at 7000rpm's.

 

i think its energized @20,000miles

 

Look at the (S4) FSM, page 4A-31: ECU pin 1S, port air solenoid valve, after the mileage switch is ON (over 20,000), the output to the solenoid should be less than 1.5v (or, basically, 0v)

 

theres more port air than that, look at how the switching and relief valves work

 

Switching valve is exclusively for the split air (back to the cat), and the relief valve does nothing more than allow vac on the back of the overboard (air exhaust)spring so the ACV can dump air. I know this ACV fairly well, I been "playing" with it for a couple of months trying to get the 5/6 ports to work perfectly with the air pump supply I've got 'em on now...Don't know if the S5"s are different or not...

 

switching goes between the exhaust ports and the split air pipe, its setup to go to the exhaust port under about 2500rpms. or theres vacuum applied under 2500rpms. they work this way from 81-02.

 

Gotta admit, don't know where the air goes before it's "switched", what you described sounds good, though. I do know now that when the relief valve/ solenoid is put "out of commision", the ACV exhausts air all the time...Thx for the clarification...