OPTI vacume line check valve?
Thread Starter
Burning Brakes
Joined: May 2009
Posts: 1,014
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From: Ft Wayne IN
OPTI vacume line check valve?
I am routing my vac lines for new vented opti. From what I understand the intake line attached to (TB intake tubing) is just an opening for clean air to be drawn through the opti by the vacume of the intake manifold vacum line. Why the check valve? And doesn't this all just create a major vacume leake? I assume the check valve is placed so air flows toward the intake manifold and checks from going back towards the opti? I guess I just don't understand the check valve reasoning and how pulling vacume through an open line doesn't bleed off major vacume? 
Le Mans Master
Joined: Feb 2000
Posts: 9,715
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From: Kempner Texas
Let's ALWAYS start off a new thread by correctly identifying the engine we're deailing with. Too many times guys don't update their avatar or signature, etc., which leads responders to think it's an engine it "ain't"
It's a sealed system. Since the source of the air feeding the vented Opti is after the MAF, it's already been measured by the MAF. I see it as being no different as the other vacuum sources (solenoids, FPR, etc.) on the intake manifold - air that's already been measured by the MAF.
Now if the source of air to the Opti was UPSTREAM of the MAF, then that would be UNMEASURED air and to me would be the same as a vacuum leak.
Just my take on this.
Jake
It's a sealed system. Since the source of the air feeding the vented Opti is after the MAF, it's already been measured by the MAF. I see it as being no different as the other vacuum sources (solenoids, FPR, etc.) on the intake manifold - air that's already been measured by the MAF.
Now if the source of air to the Opti was UPSTREAM of the MAF, then that would be UNMEASURED air and to me would be the same as a vacuum leak.
Just my take on this.
Jake
Last edited by JAKE; Aug 27, 2010 at 04:08 PM.
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It's a sealed system. Since the source of the air feeding the vented Opti is after the MAF, it's already been measured by the MAF. I see it as being no different as the other vacuum sources (solenoids, FPR, etc.) on the intake manifold - air that's already been measured by the MAF.
Now if the source of air to the Opti was UPSTREAM of the MAF, then that would be UNMEASURED air and to me would be the same as a vacuum leak.
Just my take on this.
Jake
Now if the source of air to the Opti was UPSTREAM of the MAF, then that would be UNMEASURED air and to me would be the same as a vacuum leak.
Just my take on this.
Jake
Emminently logical there, Jake.
Burning Brakes
Joined: Aug 2007
Posts: 792
Likes: 16
From: Austin Tx
It's a sealed system. Since the source of the air feeding the vented Opti is after the MAF, it's already been measured by the MAF. I see it as being no different as the other vacuum sources (solenoids, FPR, etc.) on the intake manifold - air that's already been measured by the MAF.
Now if the source of air to the Opti was UPSTREAM of the MAF, then that would be UNMEASURED air and to me would be the same as a vacuum leak.
Just my take on this.
Jake
Now if the source of air to the Opti was UPSTREAM of the MAF, then that would be UNMEASURED air and to me would be the same as a vacuum leak.
Just my take on this.
Jake
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
Confusion reigns surpreme. I saw no mention in his post that the car he was working on is a 92. Unless I'm confused even more, the vented Opti engines were all MAF engines. (Where'd you find out his engine is a 92 by the way?)
To OP: Are you modifying a NON-VENTED OPTI to become a VENTED OPTI or installing a VENTED OPTI in place of a NON-VENTED ONE?
You have a Speed Density system, not MAF, right?
If that's the case, what are you using as the vacuum source and where are you returning the vacuum? TB as the source and manifold as the return location - Vice-Versa?
Just trying to figure out what's going on.
Jake
Last edited by JAKE; Aug 27, 2010 at 04:08 PM.
Instructor
Joined: Jan 2010
Posts: 174
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From: Austin_Palm Bay_Houston Texas_Florida_Texas
I don't get it ? The intake is used as a vacumm source for all kinds of stuff !! AC/defrost/vent actuator, EGR (where applicable), cruise control, vacumm holding tank, etc. etc., and they use check valves...and there is no return air back to the intake to "zero out" this so called vacumm leak.....
So why would anyone consider the Opti vent scheme to be a source of perceived vacumm leak ?
Since when does a vacumm source need a return ??
So why would anyone consider the Opti vent scheme to be a source of perceived vacumm leak ?
Since when does a vacumm source need a return ??
Burning Brakes
Joined: Aug 2007
Posts: 792
Likes: 16
From: Austin Tx
I clicked on his pic and there in his info it says his car is a 92.
Here is the vent upgrade I did on my opti last month.
http://www.corvettefever.com/howto/16758/index.html
The vent hose kit part # is 12555323
http://www.gmpartsdirect.com/results...umber=12555323
Here is the vent upgrade I did on my opti last month.
http://www.corvettefever.com/howto/16758/index.html
The vent hose kit part # is 12555323
http://www.gmpartsdirect.com/results...umber=12555323
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Burning Brakes
Joined: Aug 2007
Posts: 792
Likes: 16
From: Austin Tx
I don't get it ? The intake is used as a vacumm source for all kinds of stuff !! AC/defrost/vent actuator, EGR (where applicable), cruise control, vacumm holding tank, etc. etc., and they use check valves...and there is no return air back to the intake to "zero out" this so called vacumm leak.....
So why would anyone consider the Opti vent scheme to be a source of perceived vacumm leak ?
Since when does a vacumm source need a return ??
So why would anyone consider the Opti vent scheme to be a source of perceived vacumm leak ?
Since when does a vacumm source need a return ??
Last edited by shadowman1; Aug 26, 2010 at 11:54 PM.
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
I clicked on his pic and there in his info it says his car is a 92.
Here is the vent upgrade I did on my opti last month.
http://www.corvettefever.com/howto/16758/index.html
The vent hose kit part # is 12555323
http://www.gmpartsdirect.com/results...umber=12555323
Here is the vent upgrade I did on my opti last month.
http://www.corvettefever.com/howto/16758/index.html
The vent hose kit part # is 12555323
http://www.gmpartsdirect.com/results...umber=12555323
I've got a mag around here somewhere showing how to mod a NO-Vented Opti into a Vented version. Would take me a while to track it down because I'd have to go through all 100+ lbs of mags to find, but I will if REALLY necessary.
Jake
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
Let's ALWAYS start off a new thread by correctly identifying the engine we're deailing with. Too many times guys don't update their avatar or signature, etc., which leads responders to think it's an engine it "ain't"
When it comes to MAP engines, for me, all bets are off. Never having dealt with MAP engines I don't know when or how it detects/measures in-coming air. So I'll leave it to you guys to sort this out.
Like "Dirty Harry" said "Man's got to know his limitations". LOL
Jake
When it comes to MAP engines, for me, all bets are off. Never having dealt with MAP engines I don't know when or how it detects/measures in-coming air. So I'll leave it to you guys to sort this out.
Like "Dirty Harry" said "Man's got to know his limitations". LOL
Jake
Last edited by JAKE; Aug 27, 2010 at 04:07 PM.
Burning Brakes
Joined: Aug 2007
Posts: 792
Likes: 16
From: Austin Tx
True also is that MAP cars are harder to diagnose mostly because of the lack of data stream compared to OBD II engines.
PS. On the opti upgrade I had to remove the P/S pump pulley to run my vacuum lines away from the belt and to get access to the lower left water pump bolt. It doesn't mention that in the article I linked to.
