Vacuum Gauge

[smokey240sx]

I bought a vacuum gauge to find out whats going on with my idle problem. I'm not to sure which line i should be testing.

[PandaS14]

It doesn't really matter. Whatever vacuum changes that are happening are going to be present in all vacuum lines. For ease of installation and trying to keep the line as short as possible, I Tee'd mine out of the brake booster line.

[NateDogg]

Just make sure you don't pull the one off of the fuel pressure regulator (on the end of the fuel rail). It will make the car run very rich, although if you have a lean problem due to a vacuum leak that may help the car run better and hence help diagnose your problem.

[eddiec]

try one of the lines near the throttle plate. closer the better.