Vac line on intake elbow.

[Formula218]

I got an aluminum intake elbow for my car after finding that the silencer hole on my stock one was covered up with duct tape. I threw it on but noticed that there was a small vacuum line on the stock one that my new one didn't have a spot for. I put it on and just left that line unplugged for now and drove the car around. It seemed to run fine but after about 25-30 miles it threw a CEL. Is this due to that vac line being open? It's a small line with what looks like a check valve in it? I think I might have to drill a hole in the elbow and put it in there.

[red_z28]

The vac line on the elbow is for the opti vent.

[Formula218]

So then that's probably the issue. I'll have to figure out a way to get it ran back into there then

[96LT1355Z28]

You will want that line tied into the intake somewhere after the MAF, this way the air going through the opti and into the manifold is fresh metered air. If you leave it open not only do you have a vacuum leak, but your pulling dust and moisture through the opti.

[95 blackbird]

Years ago I bought a trick flow aluminum elbow, in the directions it did say to drill a hole for the opti-vent line, it also came with a rubber grommet to put in the drilled hole to make sure the seal around the connector was tight. Would post pics of it but I sold the piece last year, didnt quite jive with my CAI. Try searching the web for the trick flow direction sheet, plus you may be able to order the rubber grommet as well.

[meissen]

Hrm.... do you have a vented optispark though? '94 came unvented.

[Fastbird]

Hrm.... do you have a vented optispark though? '94 came unvented.

This. Unless someone did a swap, your 94 won't have vent lines for the opti.

[Formula218]

hmmmm. it's a MSD opti if that would change it? as fas as i know the car is stock and hasn't been swapped.

[Formula218]

1183711838

[Fastbird]

Yeah, the MSD's added vents to the early style too. Makes sense now.

[meissen]

Ah - touche -- not familiar with MSD optis so I didn't realize that.

[Formula218]

my luck :P

i'm just going to get a barbed fitting and poke it through the hose coupler after the MAF.

[96LT1355Z28]

Just make sure you have the lines routed correctly, the one your holding lookes like the one that goes from the opti to the side of the intake manifold. Theres another one that routes from the elbow to the opti.;)

[Formula218]

ok, i thought there was one missing. that one dropped when i was putting the elbow on and i can't find it! i've looked all over in there. the hoses where all brittle and cracking so it just fell apart. i think it might have fallen out of the car :( where can i get these check valves? i need to order the one i lost and i'll just route new vacuum line.

the one i'm holding wasn't connected to anything lol it was just laying there. anyone know where there is a diagram of how they need to be routed so i can run new lines?


would this be causing a CEL? seems weird that the car would throw a light for the vents not being ran right if it's not even supposed to have them.

[red_z28]

http://shbox.com/1/opti_vacuum_hose.jpg

[Formula218]

i am missing the filter/flow reducer and the valve that goes on the other line (opti to elbow) can they be bought locally or usually have to order them?

[Formula218]

please forgive me for all the dumb questions guys, i've only owned opti for a couple weeks lmao. i'm trying to learn :/ the car was idling below 1k and not surging at all, didn't seem to have a vac leak at all.

if this is my opti, then is the tube below the 4 spark plugs on the right side the vent tube? where do i hook the second one from the intake manifold?
11862

so i have this right, one line goes from the intake manifold, through 2 valves into the opti. and the second goes straight from the elbow to the opti?

thanks again!

[meissen]

Here's an image which should help. You should have two open ports on the optispark (if the MSD is the same as the 95+ vented opti)
http://shbox.com/ci/opti_vent.jpg

[Formula218]

Yes! Now I just need the check valves.

[Formula218]

GM part# 12555323 if anyone ever has the same problem. That's the whole vacuum harness and valves.

[Formula218]

so it seems as though i have a vented MSD opti cap on a non vented opti housing. meaning i have a vent suck hole but no fresh air hole. i already hate optispark and i've only had it 3 weeks lol.