I just got done replacing my EGR tube and valve, very fun, especially taking the throttle body off. Seems my p0174 was likely caused by a broken EGR tube (in the ribbed section). Reinstall went fine, new gaskets, torqued to spec, all seems fine.

Except a new "absolute manifold pressure" error (1075 I believe).

I think its due to a random vacuum hose that's got me puzzled. About 1/4" black soft rubber, coming from a triple T fitting on the drivers side of the throttle body. One end seems to go to the throttle body, other to the front of the motor (sc maybe?) and the third end is this loose hose. Judging by looking at the end of it, it doesnt appear to have been clipped into anywhere. With it open the car idles rough at first, then seems to normalize. With it plugged the car runs and starts silk smooth but then throws the absolute manifold pressure code.

Could anyone help point me in the direction of what that vacuum hose is, and what it's means to do? Thanks everyone!

 

Do you have a pic? I've got all the gaskets for replacement around the EGR and its tube sitting in my garage, and intend on doing the job this weekend. i'll be sure to document the pre-project vacuum hose locations around the TB with some pics and diagrams. Maybe it'll help, but your supercharger may have lines my NA car lacks.

 

Not sure if this is complete or helpful, but my recollection is that one is for the throttle body, one is connected to the part-load breather orifice at the front of the LH cam cover, and the third is connected to the bottom of the EGR piece mounted near the coolant reservoir.

 

That's exactly the triple T I'm talking about Coupe, thanks!

The vacuum hose looks to be coming from the part load breather orifice at the front cam cover, like you said. Putting two and two together, is this hose supposed to connect to the bottom nipple on the MAP sensor on the firewall?