I tried searching, however, the search terms "vacuum line" and LIM turn up 300 idle problem threads.

Does anyone know what this line does?


My question stems from the training manual's illustration. That vacuum nipple on top of the LIM is exists on my S4 13B but is capped off. The FSM doesn't show that nipple, but instead has it come from somewhere around the subzero starting device, but the only line going to the subzero thing is the coolant line from its reservoir. Going from the top of the LIM to the throttle body seems kinda pointless.

 

That appears to be the air bleed for the primary injectors. This diagram is from the GSL-SE training manual actually. Capping it off is pointless IMO. The injectors were designed to work with the air bleed and the diffuser plate below. I'd take the cap off and hook it back up. The air bleed port should NOT be hooked up to a source of air past the throttle plates (manifold vacuum).

 

Cool, thanks.

I saw a page and a couple of threads here about air bleeds, but only for the S5, didn't see anything about them for the S4.

 

s5 turbo has two extra air bleeds for the secondary injectors