Buzzardsluck

I tried searching for this but if I missed something please point me in the right direction. OK long explantion of problems(sorry)

Last Monday a friend and I installed a Profec B-spec II BC. The car had been running flawless up to this point. Got the BC installed, took a couple test drives and everything was fine. Parked the car until Friday night and hopped in to take a spin. I notice the gauge is sitting at -5 or -6 while the car is off(needle had always returned to 0 when car was turned off). I turn the car on and the vac only drops to -10(normal is -16 at idle). I don't remember what the BC was showing at this point.

At this point I'm thinking 'no big deal must be just the way the BC works'. So I hit the road and let her get warm. After warm up I put it up to 5-6 psi of boost and let off and the vacuum only returns to -10 on the gauge and the BC shows a -99(set up to show psi). Neither gauge flucuates below those numbers but hit them exact and don't move off them. Normally the gauge hits -22 or -20 on vacuum when coming off a semi WOT run of full boost.

By this time I'm very concerned and go home(gauge shows 0 when turning car off).

So yesterday I check all the lines (seemed fine) and start the car. Well now the gauge shows -16 again but the BC is hovering around -81 to -79. So I let it warm up and give it some gas to see what the levels drop to, gauge won't go below -16 and BC won't go below -99. Also for the first time, blipping the throttle causes the car to hesitate a little and then sputter when returning to idle Also the car no longer wants to move after letting the clutch out and just cruising in 1st or 2nd gear. So I remove the BC lines and install the factory lines again but this doesnt effect the vacuum. At this point I'm very pissed and quit for the night.

Today I hook up the BC again and the lowest vacuum readings are the same -16 on the gauge and the BC never going below -99. For whatever reason today the hesitate and stutter issues at idle seem to be gone. Once again the car boosts and holds boost like a champ but the vacuum readings just don't dip below -16 and -99 on decel.

I hear no leaks, checked lines, looked at the manual(s), searched the forum. I'm going insane here , does anyone have ANY tips at all for what this might be? Am I missing a leak?

Thanks
Relevant mods:
PFS SMIC, Greddy intakes, Pettit DP & MP, Greddy catback, PFC w/commander(not tuned), Autometer boost gauge, Profec B-spec II boost controller, Greddy BOV, no air pump.

Forgot to say that I know little about cars, so it's possible I have missed something when checking. In other words, don't rule anything out.

weetbix13

you are getting a vaccum reading when the car is OFF? thats not right... something is wrong with a gauge i reckon... maybe a pinched line?

a vaccuum is developed by the spinning rotors and combustion sucking air in... there is NO WAY that i know of for a car that is turned off to develop a vaccuum.

Buzzardsluck

The gauge just didn't get pulled back to 0 that one time for whatever reason. Hasn't happened before or since. I'm really at loss on this issue, but that's that hard to do since I don't know much

Is the car safe to drive ? Anyone now if this is even a problem? Without the boost gauge I would never know anything was wrong(other than the BC never showing below -99). I do know for certain the lines aren't pinched.

weetbix13

if your gauge didn't get pulled back that one time - that makes it forever unreliable... there is a chance that there is some substantial restriction that has caused that, which is most likely your issue. is your boost gauge mechanical or digital?

if your vaccuum was a real issue your engine/exhaust would be exceptionally loud and the idle very very lumpy... you'd know for certain that it was an issue (and boost response/effect would most likely suffer).

i think there is something wrong with your gauges or sensors... either that or your vaccum leak is simply TINY - course, bear in mind that a vaccuum leak would ensure that your gauges returned to zero.

see what i'm saying?

Buzzardsluck

its a mechanical gauge. i have ordered a silicone hose set also since my car doesnt have that done yet.

weetbix13

i think you're ok... others may argue with me but if it feels fine; and your only issue if some bullocks reading from a faulty gauge - replace the gauge and keep goin.

what i'd recommend, in the meantime, is to see if you can get your hands on another gauge from a local workshop/person and test it... mechanical gauges are easy to route through a window or something for a short test.

Buzzardsluck

Is no one posting becasue this is a super easy fix and I'm just missing it? If so call me a moron and ban me but please throw a link up or something first lol.