93BlackFD

i can't figure out how or what this thing does....can someone please chime in and feel free to be a smartass...as long as you know your stuff

i suspect mine is failing based on what i've been reading, i just want to know more about it before i try and diagnose it

93BlackFD

nobody? thought you guys knew all of this

JONSKI

It's an enigmatic device that works with the airpump, EGR, and main catalytic converter for emissions control. Check page F-115 (that's the Fuel and Emissions Systems section) of the Factory Service Manual. You can view the service manual at www.iluvmyrx7.com.

puma

iTrader: (2)

i got to admit, it as always been something i never got any clue of how it worked exactly.

R Xplicit

controls the flow of air, like jonski said, in relationship with the AP, and idle air.....it is a useless piece of ****....i took mine out when i did my BOP install and the thing fell apart and appeared to not have been working for some time now....

ll

spurvo

Near as I can tell...

The ACV directs air from the air pump to the proper destination depending on what's going on at the time. Air can be directed to the ports, which lie just after the exhaust, and this is called port air injection. Isn't this the source of LIM gasket exhaust leaks? The "switching valve" directs the air to the port during cold engine cranking, warm up during idle and medium loads while cold. It allows for more complete oxidation of the HC's during cold operations. Port injection is also switched in during deceleration, idle, and when you switch the ignition to run, but don't start the engine.

Air can also be directed to the main catalytic converter through the split air injection. The switching valve directs air to the main cat during warm medium loads, normal acceleration, and heavy loads. This makes sense as you want the full combustion to occur only after it has reached all the way down to the cats under these conditions.

Where it gets confusing for me is the controls for the split air bypass, the port air bypass, relief 1 and relief 2. The split air bypass exactly matches the operation of the switching valve, opening when the split air is being used. The air circuit on page F115 indicates that this may just be a seperate circuit that opens when the split air is operating, allowing more air to go to the cats. But why there is this extra circuit, and not just a larger hose, is unclear.

The port air bypass opens during both cold and warm medium load operations, indicating that a small amount of port air is used during all medium load conditions, with more being switched in during cold medium loads. This allows some overlap for the port air injection during the transition to warm operation?

The relief 1 valve opens during warm mudium load operation, and probably regulates the overall amount of air being injected into the system, probably as regulated by the O2 sensor and fuel injector duty cycling.

The relief 2 valve is a total mystery. It seems to be plumbed to the BACKSIDE of the relief 1 valve, meaning that when it is activated through the relief valve solenoid (a vacuum signal?), it allows air pump air to be directed to the backside of the relief valve. So a positive pressure is applied to the backside of this valve, and is done so during cold cranking and warmup at idle? the relief valve is already closed during htis time anyway, so why? Hmmmm...

Anyway, I got the timing of all this from page F-197, so 'yall sould tell me I'm reading it wrong. Or add in information on the EGR system and how it relates to this story, as I suspect it has some bearing.

I can't pull mine 'cause I live where emissions ***** operate. Plus I like being clean