I am changing my injectors and I noticed a really nasty black goo inside the throttle body and plenum. It seems to be oil. If only air is going through the plenum then where is it coming from? Thats when I noticed an oil breather from the valve cover going into the throttle body. What would happen if I disconnected the line? Is it there for a major reason? and will this stop the black goo?
thanks

 

Yes it will stop it from having that black goo. Next question is what are you going to do? Put in a breather? Great idea. Now that goo is going to be all over your engine and hood. I would say you need to clean the TB every year and have done with it.

 

I wouldn't disconnect it. Your intake manifold has a tube to the PCV which is trying to create a vacuum in the engine for better sealing among other things. This extra air is already figured into the ECM's programming. It might mess up the calculations because the air draw is after the sensors so changing it may have an adverse effect on the calculations. Also you want a vacuum in the crankcase for better ring sealing,

 

Leave the breather hose alone. Make sure your PCV valve and it's related hose is not clogged up or collapsed. Very common to have the oil vapors back up the wrong way through the breather hose if the PCV is clogged up.

Also, much of that goo is actually the result of the EGR system on the TPI intake. It's got 2 little ports that feed EGR gasses into the intake just behind the TB, in the floor of the plenum. The crud in the EGR gasses jsut sticks to EVERYTHING behind the throttle blades. If you're running a functional EGR system then Aklim gave you the right advice- expect to clean it once a year. Just make it a regular part of your maintenance schedule.