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15 psi vaccum at idle????

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Old 12-28-2007 | 07:46 PM
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Default 15 psi vaccum at idle????

Hey guys,

I have a vortech blower on my car and now I only see 15 psi at idle, where as pre-vortech I was seeing the normal 20 psi.

Would a vaccum leak cause the idle psi to be higher or lower (ie a leak would show up at 15 psi not 25 psi??))


i also have a boost leak above 6000 rpms so this may or may not be related.....

Thanks!
Old 12-28-2007 | 07:54 PM
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Yes a vacuum leak would cause it to be lower. It would almost certainly be related if you also have a boost leak as well.

Does it idle weird? That might tell you to look pre or post MAF.
Old 12-28-2007 | 07:59 PM
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seems to idle just fine. so a vaccum leak would show up as a lower # then (ie 15 psi). Could that be related to the Bypass valve in any way?

since it idles ok, that means it should be pre- maf?? couldnt u get it to idle well with a UTEC even is it had a post MAF leak?

I was told to uninstall the kit and put it back on again, but i;d at like to know what I was looking for.

Thanks!
Old 12-28-2007 | 08:06 PM
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Originally Posted by str8dum1
Hey guys,

I have a vortech blower on my car and now I only see -15 mmHg at idle, where as pre-vortech I was seeing the normal -20 mmHg.

Would a vaccum leak cause the idle vacuum to be higher or lower (i.e. a leak would show up at -15 mmHg, not -20 mmHg??))


i also have a boost leak above 6000 rpms so this may or may not be related.....

Thanks!
fixed
Old 12-28-2007 | 08:13 PM
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Originally Posted by JoeDirtPharmD
fixed
Yeah, I assumed he meant HG

Depending on the severity of the leak it could effect idle, but unless your boost gauge is just off then there's a leak somewhere.

Some of the vortech guys might chime in on adjusting the Vortech bypass valve. Search a bit and they'll tell you how many threads to leave showing on the adjustment bolt (I seem to recall it being 6 threads showing on the bolt).

Seeing what you're experiencing I'd check the adjustment on the bypass valve, check for leaks pre-maf, then move down the intake tract from there. Good luck.
Old 12-28-2007 | 08:17 PM
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yeah, its inches of mercury on vacuum... i had fun tuning the car today. made some nice power but also had a couple issue up on top with some boost leaking...


nice meeting ya rich.
Old 12-28-2007 | 08:25 PM
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I mentioned it to Jeremy at PF today (was that your red Turbonetics Z with the custom piping??). Since i did the install, he was really only there to tune and not to troubleshoot problems I brought to him, rightfully so....

my buddy has a smoke machine so i'll test that when i get home. prolly have to go back to plenum spacer-less since they seem to be classic leak point.

prolly want to recheck my gauge as well to just make the line isnt pinched. ohh what fun-- FTMFL

i doubt questioning whether to ever tune another car not installed by you guys made for a fun experience. I was really embarrassed by the entire situation. felt like a complete fool. I appreciated the time you put in and the suggestions you made!! JT FTMFW

Last edited by str8dum1; 12-28-2007 at 08:28 PM.
Old 12-28-2007 | 08:29 PM
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sorry rich, just another one of those reasons where us shop owners say to have stuff professionally installed. its not that we are better than anyone else, we just do sooo many of them that we learn all the little tricks to save time and make sure things are 100%. it really has nothing to do with skill but more with reputition and doing the same things over and over.


dont worry about today, figure out the small boost leak and then have someone check it out...


again, nice meeting ya today!!

Last edited by Audible Mayhem; 12-28-2007 at 08:32 PM.
Old 12-28-2007 | 08:32 PM
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Yeah that was my car you saw. I think it's become an Orlando landmark.

Does the Vortech kit come with t-bolt clamps?
Old 12-28-2007 | 08:33 PM
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have i mentioned that your car hauls *** craig....



hahaha, he might be the only one that hasnt had a ride yet
Old 12-28-2007 | 08:36 PM
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Originally Posted by Audible Mayhem
have i mentioned that your car hauls *** craig....



hahaha, he might be the only one that hasnt had a ride yet


Not the only one... I haven't either! I'm jealous all of those junior high girls you've been picking up got to ride in it before me.
Old 12-28-2007 | 08:39 PM
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hey!! all those bitches are at least 18...
Old 12-28-2007 | 08:40 PM
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essentially, for a vacuum leak to register, it would have to be post MAF correct?


i am assuming that my BPV is opening all the way under vaccum, so that could be the only place for a restriction to vaccum, correct?

Craig, is there a reason why your rear tires are on backwards? drifting?
Old 12-28-2007 | 08:50 PM
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a hahaha,


we say that all the time, not sure why your back tires are on backwards craig. someone mixed them up

i think only we have been drifting craigs car. JK of course
Old 12-28-2007 | 09:42 PM
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Originally Posted by str8dum1
essentially, for a vacuum leak to register, it would have to be post MAF correct?


i am assuming that my BPV is opening all the way under vaccum, so that could be the only place for a restriction to vaccum, correct?

Craig, is there a reason why your rear tires are on backwards? drifting?
Register where? If it were post-MAF it wouldn't be metered by the MAF sensor and would throw the idle AFR's off and cause it to chase around and idle unevenly.

The boost gauge is read directly from the intake manifold so that would see any vaccum leak in the intake tract, pre or post MAF.

As far as my tires being backwards, I have no idea how they got that way. They looked fine the last time I saw em. Oh well, apparently they hook just fine.
Old 12-28-2007 | 10:25 PM
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Since the SC is compressing air at idle, wouldn't the vacuum reading be lower at idle by default? I would still very carefully check for leaks, but that was my understanding.
Old 12-29-2007 | 03:04 AM
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JoeDirtPharmD, if you're going to be a smart a$$, at least have your $hit together. Vacuum is measured in inches of mercury (inHG), not negative mm (mmHG).

str8dum1, yes, a vacuum leak and a boost leak would be related. A leak before you build boost would register as a vacuum leak. And taurran is correct, since the charger blows through the MAF, a leak would register before or after the MAF. A post MAF leak, depending on the magnitude, would screw up your A/F and make it run like crap, primarily at idle.
Old 12-29-2007 | 03:39 AM
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Originally Posted by undrgnd
JoeDirtPharmD, if you're going to be a smart a$$, at least have your $hit together. Vacuum is measured in inches of mercury (inHG), not negative mm (mmHG).

str8dum1, yes, a vacuum leak and a boost leak would be related. A leak before you build boost would register as a vacuum leak. And taurran is correct, since the charger blows through the MAF, a leak would register before or after the MAF. A post MAF leak, depending on the magnitude, would screw up your A/F and make it run like crap, primarily at idle.

Maybe in the states, europe its mmHG.
Old 12-29-2007 | 04:53 AM
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I think I understand. so essentially 20 xx Hg is the normal metered reading at idle assuming no leaks between the air filter and the gauge.

So if i was sucking in air anywhere from the plenum spacer to anywhere along the charge tubing up to the blower, that would register as a lower numerical reading, thus a vacuum leak.

Ok, so i ordered T-bolt clamps for all the hoses. i'm going to run a pressure test and smoke test when i get home. Hopefully that will narrow down the problems quickly!!

thanks alot for the patience with newbie questions.
Old 12-29-2007 | 05:12 AM
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str8dum1,

get yourself a 2 foot length of hose... with a large enough diameter to fit snugly in your ear. then take the other end of the hose and start probing around the plenum and pipes tolisten for leaks. It works amazingly well!!!!


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