Vacuum leaks and smoker tester questions

[busmania]

Made a handy dandy smoke machine with a paint can, two male air compressor fittings, some tubing and a cigarette. Works great.

My question is this...even if you have NO leaks anywhere, that smoke has to eventually come out of somewhere, right?

I am chasing an idling problem on a 77 bus. With the smoke test, it does not leak anywhere except where the intake boot connects to the intake. I assume this is just the "weak" spot in the system or do I have a bonifide leak there? I took the boot off and it looks fine, no cracks or anything so I just assumed that the smoke has to leak somewhere at some point. Am I flawed in my thinking?

If NO vacuum leaks, what is my next check for a poor idle?

77 bus, fuel injected, adjusted valves, timing, new temp II sensor (fixed the problem originally...now I cant get it to idle).

As always, thank you.

[BayCreamPuff]

Is it leaking between the boot and the throttle body, or the throttle body and the plenum?

If it's between the throttle body and boot, then you either need to tighten the clamp around it, or you have a crack in it and need a new one.

http://www.airheadparts.com/Intake-Sleeve-AFM-to-TB/item/022-129-967%20AC

Leaking between throttle body and plenum?

Try tightening the throttle body (2 bolts connecting it to the plenum), or get a new seal

http://www.airheadparts.com/Throttle-Body-Seal-LJetDigijet/item/022-133-073%20A
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[aeromech]

I've found that when using my smoke machine I have to start plugging leaks as they appear. Once plugged, others appear. Keep plugging until they are all fixed. I think the smoke takes the path of least resistance so that's why they all don't just appear at once.

So, you have a low idle issue? I had that on one engine and I fixed it by popping the cover off the AFM and making an adjustment. Before you turn any screws you can just slide the wiper and see if the RPM increases. If so, you can loosen a phillips head screw and do the adjustment. Before I did all that though I'd just try and adjust the AFM bypass screw and see what happens. Be sure to count the turns if you do.
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