vacuum gauge operation?

[92SL]

o.k, went & bought a vac gauge & plugged it into the the line that runs from the intake to brake booster, but I don't have a TEE for it. The gauge is showing 16 in/hg is this normal & am I hooking it up properly? oops almost forgot, the engine is a 3.1 L in a 92 supreme with 204 k's on it

[Robby1870]

Is that on a cold start, warm idle, etc? How many rpms?

[DaveFromColorado]

RPM's shouldn't matter too much - typically, on these motors, with a good vacuum and no leaks, you should see about 20 inches of mercury (in/hg) you'll loose vacuum as you hit the throtle, but once the RPM's level off (meaning if you HOLD it at 3k) you should still see that 20ish in/hg, when you let off the throtle it should pull more vacuum.

 

now, vacuum readings can mean all sorts of different things - can show sings of a bad cam, bad cam timing, bad ignition timing, pluged exhaust, etc, etc - so without knowing why you were wanting to hook a vacuum gauage to the engine, it'd be dificult to help ya figure out what problems you're trying to diagnose.

 

--Dave.

[92SL]

It almost seems as if the car isn't running at it's full potential(performance wise). I thought I had the problem figured out with doing a proper idle learn & cleaning the intake, plug wires, fuel filter, new tps, idle control valve. THe car also had minor idle issues, during cruising speed & lite throttle it kind of does this jerking/bucking for a 2 or 3 seconds until you step on the accelerator harder, then it goes away. In park the engine idles at about 850 rpm or so & periodically drops to about 650 or 700. It also does this when in gear with brake applied. I've tried finding any bad vac lines but haven't seen anything yet. THis is driving me up the wall Can someone help & poss give some diagrams of vac lines. With my vac reading only being at a steady 16 does that mean a vac leak?

[DaveFromColorado]

sounds almost like a fuel problem, not a vacuum probolem ...

 

--Dave.