erratic vacuum

[Watazz]

So I installed my boost and fuel pressure gauges (prosport) about a week ago. Havent had any problems, but today i went to fill up on 93 before i finish the build and noticed that at idle the vacuume is a little erratic. Basically it pulls about 22psi, but kind of jiggles around between 20 and 23. since i installed the gauge i have pluged the PCV, and installed the NGK TR6 plugs. Any ideas?

[Pewter02Camaro]

Re: erratic vacuum

So I installed my boost and fuel pressure gauges (prosport) about a week ago. Havent had any problems, but today i went to fill up on 93 before i finish the build and noticed that at idle the vacuume is a little erratic. Basically it pulls about 22psi, but kind of jiggles around between 20 and 23. since i installed the gauge i have pluged the PCV, and installed the NGK TR6 plugs. Any ideas?

Technicly speaking vacum is measured in inches of mercury. ;)
Odds are you have avery small vacum leak somewhere, but if it does not affect the drivability, or your fuel pressure i would not be worried about it.
It may just be the gauge as well.

[cam98aro]

Re: erratic vacuum

is the engine cammed?

i have a really nasty cam in another engine i have and at idle (1200rpm) the vacuum is not steady, it bounces around 9-11" hg

what happens if you give it some gas to bring it off idle, does it still move?

[ssms5411]

Re: erratic vacuum

Vac with fluctuate , it doesn't really stay at a certain # unless crusing around -10, WOT 0 and letting off the gas stock cam around -20 to -22 maybe less with the Powerdyne since the Vac lines and what not. My VS cam and running a vac. line to the rear of the car for the methanol injection kit reads about -14 to -16 at idle and since the longer lines about -14 or so. I forgot to plug the line when I took out the meth kit and my vac was reading like -10 to -6 had me worried for a sec. until I remembered to plug the line.

[Watazz]

Re: erratic vacuum

Just making sure. Probably a small leak somewhere. Afterall i did not ziptie everything.

[Mighty Thor]

Re: erratic vacuum

Is your discharge tube connected now?

[Watazz]

Re: erratic vacuum

Nope silicone intakes is taking their sweet time getting me my stuff.

[Watazz]

Re: erratic vacuum

I finially fixed this problem. The boost gauge jiggle got worse and the car began to idle like crap. Long story short I disconnected my evap Vacuum and now the car runs awsome and the boost gauge doesnt rattle. The EVAP is useless IMO anyway

[ssms5411]

Re: erratic vacuum

Good to hear , I got rid of mine along time ago, your vac. will flutuate though, so -20 to -23 isn't bad. mines like -15 to -17 now with the turbo and cam.