So on my 89 Gtu I understand the air pump controls the assesory ports. My cat is rattling BAD. If it isn't just a heat shield, can the cat be deleted while leaving air pump plumbed? Just bung in a straight pipe to thread in?


New to these cars! Hope 'stupid questions' is acceptable here.

 

Under certain conditions the Air Control Valve shoots air to the cat but it doesn't need the cat to function normally, so yes, you can delete the cat without affecting the air pump.
My cat recently collapsed and I just gutted it and put it back in...and the car runs fine.
Noisy as hell though.

 

I second what clokker said, b*tch screams like a banshee after I deleted mine

 

You should use a block off plate. My car has 100% emissions, except no cat. The split air pipe flange at the LIM is blocked off, and this setup works just fine.

The block off plate can be installed relatively easily without disassembling very much of the motor.

 

Thank you gentlemen!


Can someone share a thread or comment how exactly the air pump controls the accessory ports? Is it as simple as the vacuum secondary system on a Holley carb or more complex?

 

The air pump doesn't "control" anything, it powers things.
Pressurized air is run through the (inappropriately) named "vac spider" across the top of the engine to the solenoid rack (next to the alternator).
The ECU electrically opens and closes the solenoids...when closed the air just vents to atmosphere, when open, it flows back to the appropriate device/actuator (aux. ports and VDI, mainly).

So basically, the airpump is like the battery in that it provides motivation but doesn't control it.

 

Thank you sir!