Can anyone tell me what A & B are?

Would either of these cause the motor to miss if they did not function properly?

Also, if I purchase a set of headers w/ A.I.R. tubes, can I eliminate these? Or are they still required?

Any info would be greatly appreciated.
Thank you!

 

A - AIR Diverter valve assy.
B - Heater Control Valve

You need to retain 'A' if you want AIR tubes (this is the part that controls whether air is pumped to the catalytic converter through the tubes, or is diverted away).

Keeping 'B' would be a good idea, as it reduces stress on the heater core, and it also keeps hot coolant from flowing through the core when the selector on the inside is all of the way cold. Some have relocated it and had good luck.

 

Yep, what he said!

 

If you remove the AIR stuff there is a modifier for the O2 voltage (100mV IIRC) used when the air pump is flowing into the exhaust (not the cat) to compensate for the extra air so the result doesn't look lean to ecu.
If you burn proms it can be made not to impact the operation.
I am not using mine because its programmed out, but its connected still.
I don't "think" it will make your miss happen though.

 

can you expand on this a little? ive ready a little about cars going lean after the SMOG stuff is removed but no conclusive evidence.

 

When the AIR is being introduced into the exhaust manifolds the O2 will read lean and try to add fuel. To compensate for that the program puts in an offset when the solenoid is "believed" to be on. If the solenoid is not connected then the reading is not accurate. The extent of the offset in real world terms as far as it being a "real problem"I am unsure of. Mine has been programmed out. I passed emmissions testing without it and am thinking about removing it now. I probably will leave the components in just in case. There were some other threads I've seen concerning the actual effects and when the solenoid is actually adding in the manifold. Its mostly into the cat if I'm not mistaken. Only adding to manifolds is limited duty IIRC.
I should look into that some more myself.

 

I thought the air was diverted to the cat when you go into closed loop? :shrug:

 

I found another post that speaks of the AIR injection into manifolds only during open loop. The diverter valve puts air into the cat during closed loop.

https://www.thirdgen.org/techbb2/sho...hreadid=228712

 

So why the hell would there be a modifier for the O2 and AIR if the air is diverted to the cat upon closed loop? That's after the O2 so there would be no point to having a modifier in the code. It would throw off the true reading. I've never heard of the modifier either. :shrug:

 

ANHT: L849D

Used at LC9B7 and just above LCAB0 as well.
I haven't gone backwards to see what the parameters of usage are. (not enough time today)
But it is there.

 

Here's my understanding of the A.I.R. system on GM ECM equipped vehicles that have a two-stage (three-way) catalytic converter (or were originally equipped with one):

In open loop mode, and when the engine is cold, all injection air is ported to the exhaust manifold distribution tubes;

In closed loop when the engine is warm, all air is ported to the catalytic converter aspirator tube;

In open loop when the engine is warm (as in heavy acceleration) injection air is diverted from the converter to atmosphere to prevent afterfire and overheating the converter. Once load is reduced, air is again ported to the converter. The ECM may also be programmed to divert some air (duty-cycle the diverter valve) under deceleration to prevent afterfire.


As Far as I know, once the engine is warmed, the PORT valve never switches back to the exhaust manifold position, and only the DIVERT valve is operated to control air injection. But I've been mistaken before, from time to time.

 

Here is the explanation of what the system does in an $8d code speed density car.

Pulled from the DIY PROM section
https://www.thirdgen.org/techbb2/sho...hreadid=214321

 

Thanks for digging up that refresher.
I copied that into my books so I don't forget again.