Very High Vacuum Issue

[megadeth2118]

I recently turbocharged a 2004 Mitsubishi Lancer OZ (I'm running about 5psi) and at idle my profec B 2 is reading -45 vacuum. Sometimes it will stay around -35 to -36 at idle, but after driving for about 30 minutes it will begin reading between -45 and -48. I know my vacuum is supposed to be around -17 to -20 at idle because that's what all the other Lancer guys have told me. What would cause my vacuum to be so high?

I'm using a GReddy Type-S bov and it's recirculating, but I still feel lag in between shifts. It seems to boost fine, but if I release the gas and hold in the clutch to come to a stop right after I blow-off the RPM's dive down and it will sometimes stall. Could both of these issue be from an air leak?

Any help is most appreciated!

Travis

 

[Defiant]

The BOV has nothing to do with vacuum- vacuum is only in the intake between the throttle plate and the valves. Is your gauge PSI, or inches of mercury?

 

[megadeth2118]

It's a GReddy Boost Controller Profec-B Spec II. It can read psi or bar. And I wasn't referencing that the BOV had to do with the high vacuum I was listing it as a reason for the stalling.

 

[Sean485]

A TB plate that is jamming against the TB and not letting any air at all through like its supposed will cause excessive vaccum. Check to make sure the TB plate is opening smoothly, that there is no carbon buildup around the plate, and that the plate isn't closing too far (should just barely be able to see light around the edges of the tb plate when you hold the tb up to the light)

 

[megadeth2118]

It will also stay at this vacuum level while driving. If I get on it it'll go into positive pressure (boost), but just cruising it'll stay between -35 and -47.

Another weird thing is that my Autometer mechanical boost gauge won't go below about -9 vacuum, but shows boost just fine.

 

[m1nd64m3]

its probably reading hkpa (think thats it), my turbo timer reads boost and vaccum in hkpa and i get like -48 to -51 at idle while my boost gauge(in psi) reads -18 to -20, so your probably fine

 

[megadeth2118]

That was it! I had thought about that before, but the guy that helped me set it up told me it was already set to psi. Thanks for everyone's input!

 

[steve]

This was pretty funny considering around 29 in hg is a hard vacuum, like in outer space, so it would be pretty hard to create a 45 in hg vacuum.

Steve

 

[megadeth2118]

For real! I was like WTF! I couldn't understand what would make that strong of a vacuum!

 

[steve]

I couldn't understand what would make that strong of a vacuum!

The way I understand physics, nothing can. I scratched my head for a second woundering what was bothering me about the post before it dawned on me.

Steve