Just changed out the supercharger coupler. Reassembled everything and my boost gauge barely worked on the way home. It stayed at -10 and would only budge if it felt like I was giving the car enough gas to boost.

Now when I start the car it stays permanently locked at 0. I have checked for loose connections, vacuum leaks, etc. to no avail. It was fine before this job. Car seems to have as much power as before.

How does the boost gauge work? How does it get its readings?

P.*. also put in a new oil pressure sensor but that shouldn't affect it. I didn't take off a battery terminal for the job.

Fixed - that black rectangular box behind the supercharger has a tan connector. The connector has 3 round plastic parts that are essentially plugged in. Apparently this regulates boost.

The plastic clip that holds it on the box broke and I didn't mess with it for my SC coupler change so I didn't bother to look. It was unplugged. Well that was the problem just in case someone has the same problem.

NOPE.

That box is a MAP sensor....does NOTHING to regulate boost. What it DOES do is provide the signal to the boost gage, and only to that gage.

Brad is right on the money as usual. To clarify, that sensor will affect the READING, but not the actual boost. My lock tab broke off 2 or 3 years ago. It'* very hot back there behind the SC, trapped above the rear EM and firewall. I use a nylon zip-tie to hold mine in place.

I moved my aftermarket 2nd sensor out of that area for this very reason.

Ah thank you both for the clarification.