Vacuum leaks make me angry...
 

I purchased the vacuum leak tester off of one of the z guys that makes stuff on here...it's a plastic circle that fits in where the maf/filter does, and it has a pressure gage on it, and a tire air valve thingie...


plugged it in, tossed some air in there with a compressor that was charged to about 20 psi...i heard the air going in, and didn't hear any leaks...but, the gage didnt move...so i was confused.

i tossed air in the gage on it's own to see if the gage was broken, and it worked fine...tried just letting air go into the system a bit again, thinking it would take a little bit of time to fill up...no dice...wtf, where is my air going, and why can't i build any pressure? i can't hear air leaving ANYWHERE...





i then decided to try from a different place...i hooked the compressor up to a vacuum line off of the balance tube, and although i had no way of seeing the pressure with the tool thing i bought for the intake...i knew i'd be able to read the pressure off of my boost gage. wrong...it didn't move at all...but i did hear a leak. it sounded like it was coming out from right under the plenum, right under where the throttle position sensor is.









my questions:


1 - how hard is it to get to the vacuum lines under the TPS? will i be able to get to them just removing my hard pipes, or am i looking to have to pull the plenum?


2 - how come i make and hold boost absolutely fine? clearly, air is leaking out...


3 - related to #2...i've noticed my vacuum gage has crept up from the usual 18 or so pounds at idle, or inches of mercury if you want to be anal...to about 14 or 15 at idle now. i'm clearly losing vacuum, clearly hear the leak...but again, make and hold boost absolutely fine...




the car only in the past week has lost the vacuum i've noticed, and in the past week it's been running REAL rough on startup, and only once it gets full warm does it start to run a little more smooth...but still not 100% perfect...

this would explain why i'm going through plugs so fast i guess though...boost/vacuum leaks = richness = fouled plugs super fast.

youre not supposed to put more than 7 lbs in from the compressor

and if youre not getting pressure on the tester, at that psi in, its probably going thru your exhaust

what boost are you running, and what are your mods?

pop intake, full 2.5 exhaust with split dp's, tp's, and hiper cat back, UR underdrive pully, ash spec tune, manual boost controller running 15 psi, hardpipes.


and i dont understand why i should use so little pressure when doing the test? what's the difference between running say 25 psi of boost, which these cars are very capable of handling, and using that much pressure for a test standing still?


and i'm still 100% baffled how my car makes, and steadily holds boost absolutely fine at 15 psi...when i hit full boost, it does drop to 14 psi for like 1 second, then back to 15 and stays there up through redline...

you can ruin seals by overpressuring the engine. boost cannot be made sitting still.
i cant say much more because i am unsure of my thoughts on overpressuring the system.

maybe youre still making boost because you only have that small leak by the tps. if youre having a rough idle issue, but still have boost, you should probably look elsewhere for the problem

i'm starting to think i should look elsewhere too, but still...i know for fact i have lost significant vacuum pressure in the past week...and that since then i have been idling/running like shit

get a boost/vacuum gauge....

are you seriously saying that?

did you read this thread at all?

well, 18 inHG is fine no big deal, if it drops to 14-15 thats low but its only a little vacumme leak, your vacumme goes to almost 12inHG with upgraded cams, well at least in other cars i never experienced it in Z's but im sure its not to much different. it should affect you anywhere though but idle and even then, nothing big.

so you're saying that even at 14 or so "pounds" of vacuum, or however you want to read it...it's still ok?

it gets a bit better once the car is fully warmed up, but still low...

i'm gonna pull the hardpipes and see if i can get to those vac lines under the TPS one of these weekends...i really dont think i'll need to pull the plenum to get to them...




by the way, anybody have a link to a diagram or map of the vacuum lines on a tt motor? that would probably make my life a lot easier...

head over to tt.net and go thru their tech and fag pages. theres a few diagrams/writeups for vacuum lines/fixes

i found this "q" on the floor. i think you dropped it.....

can I have that "q" ? I need it for my engine.

lollers. oops

Freudian slip, right B? It would've been funnier if you had referenced 3zc with that. faq and fag are nearly interchangeable over there.

Dude....g and q aren't even close on the keyboard....what were you thinking about?

LMAO as the years pas you still make me laugh just as hard ha ha

haha. i guess that shows how i talk to my friends....sup fag

Well from what I've learned is that vacuum is a bit lower when cold. On my S130 from a cold start when the air regulator is open I get about 17-18inHG of Vacuum at idle, and when it warms up it goes to about 19-20inHG of vacuum and stays that way.