What is this tube and where does it go?

[Zixxer]

Well as I continue to the journey to figure everything out on this car as I wait patiently for a service manual to be mailed. The Chilton’s manual is almost worthless for determining the vacuum tubes even with the diagrams. Right after the MAF I'm missing a tube of some type that comes from the expandable rubber tube. The arrow in the picture points to what I'm talking about. If someone could tell me what it is and where it goes to and from I would sure like to fix that. I suspect it's a vacuum tube of some type???



PS This is not my engine, I'm looking everywhere for photos and diagrams. Mine's just a blank hole with no tube.

 

[c4c5specialist]

Hi there,
This tube is for your fresh air source to your Opti-spark ignition system. It is critical that there be one there, as this will create inaccurate MAF readings, and your Opti-spark could be contaminated internally.
While this will not cause a no-start or immediate problems, it should be rectified.
The vacuum harness includes both ends, one that goes to the Optispark, and one that goes to the intake, to suck out ozone gases from the Optispark.
Allthebest, c4c5

 

[Zixxer]

Thanks, anything special to it other then standard vacuum tubing and the ends? I can run up to Advanced Auto and pickup the tubing and ends today.

 

[Zixxer]

Well I did find the hoses on the optispark page of the chilton's manual based upon your help. It's the fresh air vacuum line but it's pretty unclear where it will plug into on the opti spark itself. I'm hoping I'll be able to see it as it appears to be on the bottom side.

 

[Zixxer]

Sorry for posting in C5 forum, didn't realize I was in the wrong one as I was reading another post. Anyways, found an "extra" vacuum hose with the end blocked by a screw cap. I can't see completely under the optispark without raising the car or getting a mirror in there but I was able to trace vent system "harness" tube so I know it's in place. I suspect the optispark was replaced with a 95 or earlier that doesn't have the fresh air vent and the last person just took the tube and blocked it off. I'll have to get the car in the air to verify but I'm betting that's the case.

Will it be ok to continue to use this older optispark or should I start thinking about replacing it. I know it was replaced by the last owner in our discussions of mechanical work prior to selling it.