So to make sure I’m covering all my bases on dialing in the top-end refresh I purchased a simple smoke machine. Do I hook it up to where the brake booster hooks into the plenum? Do I need to hook it up anywhere else to make sure all the engine-specific vacuum is checked. Since I have it, what else should I use it for?

 

I'm not sure of all the uses for them, but one I've seen is finding exhaust system leaks by plugging the machine into the tail pipe and seeing where any smoke leaks out.

Intake leaks, vacuum system leaks, possibly useful to find HVAC vacuum leaks...
I'm actually building a smoke machine to help with the same sort of issues in my 928 project.

 

On mine I rigged it to intake, just aft of air filter. There is a post by a member on how to do it, cannot find,

 

I looked for a post too with no luck. I’ll check again.

 

I hooked mine to the MAF to look for leaks. Bought the parts Home Depot. Then put it back on where the MAF goes and lit the cigar.


The cigar way.

 

So I wanted to share some pics of my set up and a couple places I hooked to. Initially I hooked to the vacuum line on the WUR. It seemed convenient. Then I hooked to the blue vacuum hose followed by the white hose. As pictured, I got smoke coming out of the air pump system which I thought was strange. I thought there was a screw down that hole. (Air pump is not hooked up anyway but everything is plumbed). The last place I hooked to was the top of the plenum. Happy to report there were no vacuum leaks minus the air pump part. Any direction on that is appreciated.

 

Looking at that engine bay I’m not surprised you didn’t find any problems.

 

So is this supposed to be an air intake? You can barely see the smoke coming out.

 

That's the 930 diverter valve (93011314701). It's part of the air injection system. I have my broken one in a box on my desk. When I blow on that hole I can hear air passing through the compromised diaphragm and coming out the vacuum tube. I think that is a sign your valve is not working.

If you put a vacuum pump on the nipple (not that hole) does it hold pressure?

 

Good observation! I don't know anything about the internal anatomy of the diverter valve but I'm pretty sure it shouldn't vent to atmosphere there. Maybe one of the internal diaphragms is leaking? Where was the smoke source plugged in when you get smoke out the diverter?

 

It was plugged into the blue hose. When the engine is running, you can just hear the “sucking” of the air. As recommended by @copperstew I’ll hook up the vacuum gauge tomorrow to see if it holds vacuum. I don’t have the air pump hooked up currently but I want to make sure I’m not causing the car to run as well as it can.

 

Sorry for the delay. I kept forgetting to test the vacuum. It does hold vacuum when it is hooked up to the nipple. Any thoughts?

 

If the top of the unit holds vacuum then there's no split in the diaphragm. So smoke is not coming in through the vacuum line. The other options are via the inlet from the air pump (nope), the bottom/output of the diverter into the air injection tubes to the heads (nope, though if an exhaust valve is open and the check valve in the air injection pipes is broken I suppose that's theoretically possible), or (most likely) from the air box back into the outlet/bypass of the diverter valve.

 

Thanks Rob. Any suggestions what should be done, if anything? As a reminder, I don't have the air pump hook up.

 

Stick a rubber cork in the opening of the airbox on the passenger side to block any unfiltered air from getting sucked through the air pump tubing? I don't think that this is causing any real running issue for you, but there's no point in allowing air to bypass the air filter.

I can't remember, did you fix your cold control pressure by readjusting your WUR?