air pump/emissions question

[jaidedeye]

i know that the air pump is originally hooked to hoses that go to a check valve then to the cats and to the back of the heads.....

my question is this......can i just run a hose from the air pump straight to the cats??? do i really need the hoses to go to the heads to pass the sniffer?

 

[HISSIN50]

i am not good with this stuff, but i think air is diverted differently when the car is cold vs hot. so keeping it the same may be necessary. someone recently had a nice write up on a thread about how it works. if you are keeping the stuff on, why not keep it original?
good luck and bump.

 

[jaidedeye]

well i had removed the hoses and stuff when i was running an off road x pipe. but now i have my mac h-pipe on and want to put everything back on....the only problem is that i dont have the check valve and hoses for the heads anymore

 

[jrichker]

Here's an explnation of how it works...
Codes 94 & 44 - Check vacuum lines for leaks, & cracks. Disconnect the big hose from smog pump: with the engine running you should feel air output. Reconnect the smog pump hose & apply vacuum to the first vacuum controlled valve: Its purpose is to either dump the pump's output to the atmosphere or pass it to the next valve. The next vacuum controlled valve directs the air to either the cylinder heads when the engine is cold or to the catalytic converter when the engine is warm. Disconnect the big hoses from the back side of the vacuum controlled valve and start the engine. Apply vacuum to the valve and see if the airflow changes from one hose to the next.

The two electrical controlled vacuum valves mounted on the rear of the passenger side wheelwell turn the vacuum on & off under computer control. Check to see that both valves have +12 volts on the red wire. Then ground the white/red wire and the first solenoid should open and pass vacuum. Do the same thing to the light green/black wire on the second solenoid and it should open and pass vacuum.

Remember that the computer does not source any power, but provides the ground necessary to complete the circuit. That means one side of the circuit will always be hot, and the other side will go to ground or below 1 volt as the computer switches on that circuit.

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host)

http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

http://www.veryuseful.com/mustang/tech/engine/images/88-91eecPinout.gif

 

[jaidedeye]

jrichker...hey thanks for all the electrical aspects of the emissionds system...but i just need to know if i can get away with just running a hose to the cats....

 

[jrichker]

Since the system switches from heads to cat converters, you may find you have problems with emmissons when cold.

There is a one way check valve that goes between the pump and the cat air tube. Don't omit it or you may find that the system chokes when pressure in the cat area exceeds the pressure put out by the pump. If you have an exhaust backfire without the check valve, you could damage the pump.