I just finished installing a T04s turbo over the weekend and when I went out to test the car, the stock boost gauge didn't work. It stays in the position when turn the key on(not starting the engine) and when you start the engine, it doesn't go back to the bottom of the gauge. I was wondering why this was happening. My thoughts are that it might be because my BAC connector wiring was broke or it has something to do with the twin scroll system being removed. When I drive the car and start to accelerate, I see the mechanical gauge(aftermarket boost gauge) start heading for boost, but the stock one remains stuck at that position. On the stock turbo, the stock gauge would always start rising as well. So I know it works. Have any of you who have installed bigger turbos ran into this problem? Also where did you connect the vacuum line for your external wastegate,boost gauge(aftermarket), blow off valve, and pressue sensor. I assume you blocked off the vacuum port for the twin scroll system (vacuum port that has the metal line that runs from the actuator on the stock manifold connected to it). Any other advice you could give me from your experiences with upgrading turbos would be greatly appreciated. It would help me get my car safely running down the road.

 

if you're running a T04 you'd better be using an aftermarket gauge

 

usually the wastegate line is plumbed from the nipple on the front of the impeller housing. The boost gauge, blowoff valve, and pressure sensor all come off the upper intake manifold.

 

yes I am using an aftermarket gauge, but It would make me feel a little safer if the stock one is working. I would think that the signal the ECU is getting is coming from the same place the stock gauge is getting its signal from. It makes me wonder if the ECU isn't getting the signal at all.

 

is the stock pressure sensor hooked up??

it, the BOV, and mech gauge should be off the UIM.

the wastegate line should come off the turbo compresser