94VRotary

iTrader: (6)

I received a midpipe from forum member here.
As I was trying to install it, I realized the air pump was feeding air directly to main cat.
Since this mid pipe does not have flange for air pump hose, I'll have to remove air pump.

So I did some research about air pump removal, many people (including Dale) say about lumpy idle issue once air pump is gone due to ECU program.
I looked through website below and some people said idle issue can be resolved through inserting filter on one of solenoid.

Air Pump Removal

I wanted to know if there is any other possible way to install midpipe/remove air pump without PFC.

j9fd3s

iTrader: (3)

you can leave the air pump on, and remove the cat. the split air pipe only feeds air to the cat on decel and a couple of other transitions. the air pump air primarily goes to the exhaust ports, or what Mazda calls port air.

so if you're worried about the idle, just put the mid pipe in, and leave the split air open (it needs to vent).

if you want to know when it works, put a whistle in the hose, and you can listen to it not doing much

94VRotary

iTrader: (6)

So no air is getting sucked in through that pipe, right?

What is all these o2 sensor interferes with idle issue or running too rich.
The air pumps into main cat, so I assume those are non-sense??!?

j9fd3s

iTrader: (3)

no, air comes from the engine.

i don't really understand your question, but the the air pump air is only pumped into the cat on decel, and a couple of other transitions, the rest of the time that the air pump is on, it is injecting its air into the exhaust port, or what Mazda calls "port air".

the exhaust ports are ahead of the o2 sensor, so the o2 sensor reads lean when the engine is in "port air". the air pump air helps the gasses coming out of the engine more completely.

if you don't understand the training manual explains the system in detail, http://foxed.ca/rx7manual/manuals/93...highlights.pdf

or warm your car up, and unplug the air pump, and see for yourself (if the cat is installed don't run it too long, under a half an hour)

cewrx7r1

iTrader: (2)

The air pump blows air into the rear exhaust port and into the cat. Leaving the AP functioning without a cat will not affect the idle.

The only way to remove the AP without affecting the idle is with a PFC or other ECU. With a PFC you need to turn off the O2 Feedback switch.

Now to why this problem occurs. The AP dilutes the exhaust with air to fool the O2 sensor and ECU along with O2 FB to think it has a real 14.7 AFR. The AP leans out the exhaust gases!

When you turn off the AP, the gases reaching the O2 sensor read richer. Thus the O2 FB system reduces fuel which causes the engine to go lean.

94VRotary

iTrader: (6)

Thanks for the input guys.

I'll keep the air pump, replace main cat with mid pipe, and leave air line vented.
Should I put something over that air line, like mesh or just leave it alone?