sorry for the length.....just tell me what you think
my car has been having a slight miss lately and i think this might be the culprit.....

alright......when i first got the car i was looking underneath and and the vaccum line going from the opti to the intake manifold was unpluged and loose......so i pluged it back in and test drove it, and for the one of the first time, it barked the tires going into second, so i firgured it must have helped.........so then im looking under it awhile later and i see that its disconnected again(who knows how long it was disc. and dangling, this was like 10k mi later....), so i start looking and it turn's out that the bolts from the harmonic balancer are knocking it off, so i say oh well......and plug the line, and the opti port open to dust and oil and ****......it stays that way for at least 10k mi, and during these mi, with the line disconnected and the opti open, it runs the 13.6......then recently i remembered it and started to mess with it some more.....so i was trying to bend the port backwards so that i could plug in the line....and it broke off.....so i found a peice of plastic tube and glued it into the hole where the port was on the opti.... and then connected the line....this was ahwile back
now the miss is definetely here, and it wasnt always this way....this might have something to do with it????????

the car has new plugs and accel 9k wires w/unknown mi.....the car did not miss after i put the plugs in when i first got the car......

 

UPDATE:

I just unplugged the vac line going from the intake manifold to the opti and plugged it with a bolt....however the opti port is still open and exposed to the air, but its fixed, the miss is gone, 100% difference. However, the car is still not super super extrememly smooth up top in the rpm band.

What exactly does that vac line do? Is it like some kind of vac advance/retard or something? Is it ok for me to leave the opti exposed to the air? Is it ok to plug the vac line to the intake?

PLEASE help, i do not want to damage the opti......

 

Thata the vac line that keeps the opti vented. IE, it keeps moisture from condensing in there by circulating fresh air through there at all times. so...if it is plugged, air isnt circulating, and that means bad news for the opti after a while......hook it back up the factory way and be safe about it

 

Yea, don't leave that open to the elements or you will be doing an opt swap- doing mine this weekend. If nothing else just keep it plugged. Not sure about gluing back together, that might go south after a while. These things are evil so be careful what you do to it!

 

I think you guys are confused about which line im talking about. The factory line that goes from the opti to the "fresh air" in the air intake elbow is still intact.......I'am talking about the vac line from the opti to the intake manifold, is ok to leave that unplugged and the opti open?, also is it ok to leave the vac line pluged to the intake?

 

The line coming from the intake is the vacuum source. It's there to pull air in from the intake elbow, through the opti, and into the motor. If either one of the two is off then it won't be long before you will be at the parts store. Especially if you leave the opti open to the elements. The original opti 93-94 (non-vented) was merely sealed and had big problems with condensation building up and corroding them out. This venting setup was GMs answer to the problem

 

If your sucking air through the vacuum line into the intake elbow it will cause your car to run rough also because it is unmetered air comming in after the MAF.

 

please read my posts accurately before you respond. The vac line going from the intake elbow to the opti still maintains its factory connections..thats not an issue. The line going from the opti to the intake MANIFOLD is not hooked up however. The intake line is plugged, but the opti is exposed. On another fbody site, they say that both lines are used to "flush" clean air through the opti. What i want to know is if the line going to the intake controls any type of advance or control of the opti? What can I do, can I plug the opti, or will that hurt something?

 

The vacuum line that connects to the intake is there just to pull fresh air through the opti. It does not control anything in the Opti. No vacuum advance, etc. Its job is just to pull fresh air into the opti incase of any moisture build up in the opti. The only prob if you disconnect it is of course to plug the intake port and you will be running almost the same set-up as the 93-94 opti. The fresh air being pulled through does do alot to keep the inside of the opti dry.

 

Make sure you have a vacuum restrictor in line from the opti to
the manafold otherwise it will look to the engine that a vacuum
port is open. The restrictor is about 1-1/4 inches in dia. 1/4 inch
thick with an input and an output nipple , and I beleive that its
blue on one side and white on the other.

Also mine has a squeeze type hose clamp to hold it on the opti.


Dave B

 

Dude.....read my last port very slowly. It takes both lines to complete the vacuum system for the opti. I'll see if I can find a picture for you

The suction aka vacuum does not come from the line going to the elbow. The fresh air is pulled from there, then through the opti, then to the manifold.

None of this has anything to do with advance or other effect on the opti. It's only purpose is to "flush" the opti with fresh air to keep condensation down,

 

OutKast I dont know if your last comment was for me or not, but
what I'm saying is that without the restrictor inline between the opti and the manifold to the engine it probably looks like an open
vacuum line, in other words, on mine when I pull the line going to
the opti from the manifold at the opti , I get no change in engine
speed also if I hold my finger over the hose there is no change.

On my car the input hose comes off the intake elbow through the
opti out through the other hose to the restrictor and then to the
manifold.

I hope this will clear up what I'm trying to get across.

Dave B

 

94 Roadhog - Not directed to you. You're right on with what you're saying. I always thought that what you call the restrictor was a check valve to keep from pushing bad air through the opti during a backfire or such. Restrictor sounds good too though. Either way it should be there.



Blue96z28 - take a look at the pic below

http://bedford.no-ip.org/optiflow.jpg

 

LMFAO!!!! Did you draw that just for this guy? He is being pretty dense...

 

Man, I had to I think of myself as being able to exlpain things pretty clearly but this time it was evident that it would have to go to the next level.

I have a GM drawing of it somewhere from when I converted to the vented setup but couldn't find it. What else am I going to do at work around midnight?