Hi, my 1998 A4 Quattro Turbo , had the intake vacuum line at the front of engine, become disconnected, at some point, a few months ago. It was old and hard, so I have some new vacuum line, but can not see( from the top, anyway ) where this line connects down below. I have not been under car yet. Engine light has been on for quite some time , reading lean on bank one. Engine is rough at cold start. It was only today I discovered the unhooked open line. I have looked at vacuum diagrams but can not figure it's lower hook up location out. Car will not pass NYS inspection with engine light on, and it is 4 months over due for inspection.
Thanks,
Pete
Hudson Valley , NY

 

Is this a 1.8 or 2.8?

If you google 1998 audi a4 (1.8 or 2.8) vacuum hose diagram, that should be a good start.

 

If it's the line on the intake manifold then that vacuum line leads down to your diverted valve, having this disconnected will explain rough idle.

George

 

Pop the coolant hose (that goes to the turbo inlet) out of its clips on the timing cover. You should find the hose I believe you're looking for, hiding underneath that coolant hose (in the same set of clips). If it is and it's disconnected, as george1546 stated, it goes to the front nipple on the intake manifold. It connects to the actuator that opens your wastegate (via your N75 valve).

G/L

 

thanks guys ! .... this is the line I am talking about !
can I connect this from the top ....or do I need to get under the car
and connect from there ?

 

Top is fine.

 

What is the proper size of this Vacuum line .... ( 4mm - 5/32 ) ?

 

3.5mm ID