Vacuum Gurus needed!
Thread Starter
Former Vendor
Joined: Jun 2001
Posts: 7,204
Likes: 6
From: St Marys PA
Vacuum Gurus needed!
Guys,
I just got in from about 11 hrs of fittle F'in around with me car. Yes I am pathetic I know! Got my new tach with shift light installed, new hypertech coil/distributer and rotor. Man what a difference in the startups. I then started looking for my mysterious oil leak again. I for some reason think it is due to too much crank pressure for some reason. I have been reading as much as possible on vacuum systems to help in situations like these. I decided to pull the drivers side pvc to see how much it was pulling. Well it was seemed pretty adiquete. I then moved to the passengers side and there was nothing! Nothing at all! I thought what the heck! I then took the vacuum line off that goes up to the purge canister located right below passengers side vacuum line on the TB. The air was wistling through that one. It was a VERY strong pull even at idle. So I thought that maybe the other hose had an obstruction. I pulled the line off the throttle body and still at that point there was nearly no vacuum at all. I thought maybe if I hand rev the engine it will increase as more air passes throught the TB. I performed a few revs and still nothing! I decided to pull the TB off and investigate the passageways. After taking the TB off I blew threw the upper hole and air went freely throught the passage I investigated further and found that the air travels up to the top of the TB just under the Tune Port cover. From there it travels down through the hole that subsequently is blocked 3/4 of the way by the Freakin P.O.S. Air foil *nut*. If you have one you know what I am talking about. Still air could get through there. The air then travels out from around the air foil into the SR. This path must have considerably less vacuum that the lower port. I began thinking that perhaps I could switch the two lines. That might give me the added vacuum at high RPM and keep the engine oil from leaking. I assembled the entire TB after first cleaning the IAC pin, etc. (idles much better now).
Got the vacuum lines switched and HOLY cow. That baby is really drawing now! I could hardly pull the dip stick out. And when I did I could hear the air wistling down through the opening. Surely this is more than enough vacuum, but am I hurting anything by having too much vacuum on the crank? I would imagine its doing the same as an aftermarket crank case air pump would do. The car seems to rev much, much quicker now. I want to hear you guy's thoughts on the idea. Thanks a million.
[Modified by ski_dwn_it, 11:15 PM 4/13/2002]
I just got in from about 11 hrs of fittle F'in around with me car. Yes I am pathetic I know! Got my new tach with shift light installed, new hypertech coil/distributer and rotor. Man what a difference in the startups. I then started looking for my mysterious oil leak again. I for some reason think it is due to too much crank pressure for some reason. I have been reading as much as possible on vacuum systems to help in situations like these. I decided to pull the drivers side pvc to see how much it was pulling. Well it was seemed pretty adiquete. I then moved to the passengers side and there was nothing! Nothing at all! I thought what the heck! I then took the vacuum line off that goes up to the purge canister located right below passengers side vacuum line on the TB. The air was wistling through that one. It was a VERY strong pull even at idle. So I thought that maybe the other hose had an obstruction. I pulled the line off the throttle body and still at that point there was nearly no vacuum at all. I thought maybe if I hand rev the engine it will increase as more air passes throught the TB. I performed a few revs and still nothing! I decided to pull the TB off and investigate the passageways. After taking the TB off I blew threw the upper hole and air went freely throught the passage I investigated further and found that the air travels up to the top of the TB just under the Tune Port cover. From there it travels down through the hole that subsequently is blocked 3/4 of the way by the Freakin P.O.S. Air foil *nut*. If you have one you know what I am talking about. Still air could get through there. The air then travels out from around the air foil into the SR. This path must have considerably less vacuum that the lower port. I began thinking that perhaps I could switch the two lines. That might give me the added vacuum at high RPM and keep the engine oil from leaking. I assembled the entire TB after first cleaning the IAC pin, etc. (idles much better now).
Got the vacuum lines switched and HOLY cow. That baby is really drawing now! I could hardly pull the dip stick out. And when I did I could hear the air wistling down through the opening. Surely this is more than enough vacuum, but am I hurting anything by having too much vacuum on the crank? I would imagine its doing the same as an aftermarket crank case air pump would do. The car seems to rev much, much quicker now. I want to hear you guy's thoughts on the idea. Thanks a million.
[Modified by ski_dwn_it, 11:15 PM 4/13/2002]
Le Mans Master
Joined: Feb 1999
Posts: 6,172
Likes: 11
From: somers, ny
Re: Vacuum Gurus needed! (ski_dwn_it)
Jess, that passenger side hose that runs from the valve cover to the TB, does NOT pull vacuum!!!!!!!
The PCV vacuums the crankcase unless there is no vacuum like at WOT. Then the blowby pressure pushes out thru the passenger side and into the TB. I have mine disconnected and would have a breather if i could find one that fit the valve cover. You shouldn't have much positive crankcase pressure if all is working correctly. I would suggest just disconnecting that passenger side hose. Worked for me.
The PCV vacuums the crankcase unless there is no vacuum like at WOT. Then the blowby pressure pushes out thru the passenger side and into the TB. I have mine disconnected and would have a breather if i could find one that fit the valve cover. You shouldn't have much positive crankcase pressure if all is working correctly. I would suggest just disconnecting that passenger side hose. Worked for me.
