i made the change to an s5 turbo and manifold on my 88. the boost gauge doesn't read anything. it sits at 20 in/hg regardless of what the car is going. idle, moving, accelerating, revving engine, etc. i checked the sensor on the passenger fender and it looks fine. i ran a new vacuum line to the sensor and even tried another vacuum port from the manifold - nothing. the reason i bought the rtek was so that i could retain factory gauge function and they assure me this is not the cause. the gauge worked fine before so i hesitate to think that the gauge or sensor failed as a result of the work done. i'm more than willing to accept i installed something wrong but am not sure where to look first.

 

You're using an S4 Boost Sensor? If so, then the Brown/Red wire of the sensor is the output signal which goes to both of your ECU and Boost Gauge. It should read close to 2.5 volts w/key to on, does it?

 

Yes I am using an s4 sensor and yes it does