Digital dash works great, I thought
 

I hadn't seen this as a problem until I saw a z31 with a fully functioning digital dash! Everything about my dash works fine but on the tachometer the lines which normally raise up as you increase throttle are always on. I have seen many where the tach shows up as just the bottom bars lit up and when you rev it the other ones light up. I'm not sure if this is clear, I can take pictures.

you will find mounted on the wheel well forward inside the engine room a small squarish black box that states boost sensor on it, Unless it has been removed. It should have a vacuum hose going to it and a wire with connector. that device is what moves the bars up and down.

dash prob
 

I have the same problem with my 87. The bars are constantly lit up and do not respond to engine revs. Could u put your own vac line on the boost sensor and suck on it to watch the gauge go up and down? lol?

who is going to watch gage while you suck? just run a vac line over there not that hard. got wires going to it?

Me, lol i got a 6 foot vacuum line.I can suck on it while sitting in the drivers seat. Hey...you want something done right u do it yourself!!