Running lower vacuum.

[Aphix]

I installed a boost gauge as my first mod so I could get the base measurements on everything. My stock vac was 20 in.Hg at idle. After installing an injen style intake pipe and filter along with david brode uicp and 1st gen BOV I am running 17 in.Hg at idle. At first I thought I had a leak. But then I got to thinking that my air/fuel ratio would be thrown off and I would idle funny (Idk exactly how much a leak throws off vacuum so I'm unsure), but my car idles fine. Is this a result of a free'er flowing intake system or is there something else I'm missing?

 

[Boost92awd]

Do a boost leak test, and come back and tell us the results. My bet is that you have a boost leak. Even though 17-20 Hg is normal. Did you lose any boost PSI?

 

[AWDTSIer]

^ Agreed.
Do a boost leak test!

 

[Aphix]

Nope boost holds fine at 12 psi. But spikes at 15.. I'm hoping a mbc will fix this. I dont have a leak down tester yet, but the two uicp couplers are tight as hell I just checked them. Thats the only thing thats been touched. But for the sake of time does anyone know what size of a leak would make me lose 3 in.Hg.? Or could a free'er flowing intake put less drag on it and make less vacuum.

 

[Boost92awd]

Just because your couplers on your UICP are tight dosent mean anything. Do you relize how many vaccum lines are in are engine bays, way to many. Doing a intake and UICP your taking stuff off and putting new stuff in all while moving things around in the engine bay. It dosent take much to cause a boost leak. Just bumping or pulling on hoses can cause one. Do a boost leak with soapy water and report back.

Check out VFAQ Site - Visual Frequently Answered Questions. You can make your own boost leak tester for under $10.

 

[jenkinsfan1]

???? thats pretty normal vac you probley have a really small boost leak nothing to worry about but those numbers are AVG.

 

[snowborder714]

17 in.Hg. is normal and you have nothing to worry about

 

[Aphix]

I know 17 in.Hg is normal but its the fact that before the mods I was running 20 in.hg that worries me. Also, the snorkel-like adapter before the filter was kinked shut from a previous accident, so that might have thrown off the real vacuuum measurements.