jrock

Does anyone know what the purpose of the IAC one way valve is? This is connected inline w/air tube, flowing air from bottom of throttle body to a Y tube that then splits into each side of the lower intake mani.

Is it only put in place after s/c is installed? A friend did not install his and plugged those tubes off, reasoning that enough air goes into the mani from the s/c so this extra air is not needed..his motor runs strong.

I had everything apart to do knock sensor wire and this came up during reinstall...the valve does not look right,,,as pictured. may just need to cut the tube to get rid of angle, but i thought it fit better b4. does not seem backwards tho?

eddieleephd

it is used to prevent air from being forced the other way!! Your friend has probably not thought of start up or is right and it is not needed really do not think plugging them up would make a difference as long as you still have PCV Positive Crank case Ventilation

jrock

that makes sense..thx

eddieleephd

no problem!

jrock

Gadget chimed in on this topic...interesting about the injectors.

"The older Denso injectors did not have a very good spray pattern. To enhance the fuel atomization at idle air was pulled through the tip of the injector by manifold vacuum to enhance the atomization. These are called air tip injectors.
>
> In boost, air is pushed into the tip of the injectors and back out to the throttle body and it takes needed fuel with it making the engine run even leaner. The one way valve prevents this back flow.
>
> If you have the upgraded URD injectors you block off this system."

So ill be removing mine since i have the upgraded injectors.