So you have a high idle, Code 33 - MAP High, or have a hesitation that just won't go away? It could be a vacuum leak! Here's a simple way to build a smoke machine to ferret out the leak source.

Tools needed:

Air compressor (12v powered model is OK)
Quart sized paint can ($2 at lowes)
1/4" to 1/4" hose barb ($2)
Needle inflator or another way to attach the compressor air to the quart can (I used a threaded blow gun attachment)
10 foot 1/4" vinyl hose section
Funnel, 2 liter bottle, or some other plastic thing to fit into your intake.

hammer
punch
propane torch
plumbing solder and flux
sand paper

1) Sand the top of the quart can lid until it's nice and shiny. This will remove oils and clearcoats that we will not want in a bit.

2) Mark the quart can lid in 2 places, and using the punch and hammer, make two holes.

3) Insert the needle inflator and 1/4" hose barb into your two holes. They should be tight, and may need to be smacked into place.

4) Once they are in place, flux the lid and connectors, and solder the hosebarb and inflator connectors to the lid.


How to use the smoke machine:

5) Take a 100% cotton rag, soak a corner in WD-40, kerosene, or some other flammable oil. Light the rag, and insert it into the can. Let it burn by itself for a good 30+ seconds. Then put the lid on and tap it down with a hammer.


6) Connect the air compressor to the "inlet" and turn it on. Make sure the pressure regulator is set LOW (5psi). If you are using a 12v car pump it will probably be fine as-is.


7) Connect the 1/4" vinyl hose to the "outlet" hose barb


8) Connect the other end of the vinyl hose to something that will fit in your intake. It could be a PVC pipe cap, a 2 liter bottle, or a funnel. Figure out what works, and drill a hole and stick the hose in. I used a 1 liter plastic orange juice bottle.


9) Smoke should be pouring out of your machine. If not, it may take a while for enough embers to be throwing smoke for you to see it. If after a minute no smoke is coming out, you may need to relight the rag.

10) Insert the bottle/cap/smoke injector into your rubber intake tube. Secure it.

11) Watch for smoke to pour out of your engine somewhere. You've found the leak! Better yet, it didn't cost you $2000 for a professional leak detecting machine!

*** Disclaimer: Fire is dangerous. Building this contraption is the equivalent to starting a back draft in a can. Opening the can while the rag is lit could cause a flare up and potential loss of eyebrows, or WORSE. Because the can is metal, it is safe to let it sit until it completely cools down. Once it does, you can open the can and douse any remaining embers with water, before storage. Also note that high temperature air is exiting the can, and vinyl hose may not like that very much. If your compressor puts out too much air, you can build an accidental blow torch. As always, be careful, don't leave this unattended, etc etc. Use common sense.

One more edit: It may help to put a mesh filter or perhaps stuff some steel wool into the 1/4" tubing, just to keep flaming bits of cotton inside the machine. I did not have any problems, however, YMMV.

[This message has been edited by ryan.hess (edited 06-24-2010).]

The best method to check for vacuum leaks is a smoke generator and your article is very informative on how to make a DIY variety. I use this method but use cheap stale cigars to supply the smoke.
BTW, pushing for positive ratings is against forum rules so be careful not to upset the moderator. If your posts are helpful the positive ratings will come.

------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, 3.4" Pulley, N* TB, LS1 MAF, Flotech Exhaust Autolite 104's Custom CAI 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

Great stuff, Ryan...Wouldn't expect less from you. I'd give you that plus if I hadn't given you onebefore.

BOb

This thing is so handy to find leaks, you'll be using it in all kinds of places... Rattle in your exhaust? Stick a rag in your tail pipe and smoke it out! Bees made a hive in your air cleaner? Smoke 'em out!

How about the gas fitters way just compressed air an air guage and a plastic spray container full of soapy water no need to pollute the lines with carbon?

With the engine running, I use a 3' length of surgical hose with one end stuck in my ear. I probe with the other end around all the usual suspects. A vacuum leak shows up with a hiss.

Arn

Looks similar to the one TeamZR1 built that i've seen.
I use a Rotunda/Ford machine,but an evap smoke type machine comes in handy.
*The TeamZR1 machine uses auto trans fluid for smoke.
No need for flame,only need to heat the can.

[This message has been edited by DefEddie (edited 06-25-2010).]

Does this little gizmo risk mucking up a MAF sensor?? Thought I'd get an oppinion before I screw something up.

Bob

I saw a smoke machine used on Powerblock TV and they demo-ed how to find the leak. Smoke comes out whereever there are leaks.
Grreat little DIY device, save money, save time, and pass emissions testing. YEAH!!!

quote Originally posted by RCR: Does this little gizmo risk mucking up a MAF sensor?? Thought I'd get an oppinion before I screw something up. Bob

Anything risks mucking up the MAF. Even a K&N filter will do that. Particulates in smoke (whether from a DIY or expensive machine) can attach themselves to the MAF wire and throw off the readings. Just remove it if you've got one... Or clean it after you're done with MAF cleaner.

quote Originally posted by Australian: How about the gas fitters way just compressed air an air guage and a plastic spray container full of soapy water no need to pollute the lines with carbon?

That would require a lot of air, and any bubbles on the underside of the intake, you'll never see. Smoke, however, drifts, and you'll see at least the general area of the leak.

[This message has been edited by ryan.hess (edited 06-27-2010).]

Well, I tried it and I've got a lot of smoke coming off the throttle body/manifold interface. Apparently a bad gasket in there. Should explain the awefully high idle.

Could use a double walled can (or can within a can). Darn thing gets hot.

Bob

[This message has been edited by RCR (edited 06-27-2010).]

Since tough times call for desperate measures my preferred vacuum detection machine is a can of brake cleaner, it always does the work for me. Great write up!

Thought this may not be the "safest" way to go about it, this is a quick little trick that has always worked very well for me.... (Have a fire extinguisher handy just in the remote case there is a problem)

I use a can of brake cleaner or starter fluid with the little red tube attached. Just spray along the lines, and around the connections. If the engine rev's, you have a vacuum leak in the area where you were spraying. As we all know, the vacuum lines all go into the intake, so if it sucks in the starter fluid vapor into the vacuum lines, the engine will rev up.

I use a can of choke cleaner and start spraying it in different areas until the idle changes when it sucks it into the engine. Then you've pretty much pin pointed the leak. The garage that does my repairs uses that technique and it works every time.

[This message has been edited by Mike Murphy (edited 06-27-2010).]

Those using carb cleaner better have a fire extinguisher handy! Not that it will save you from any explosions or flash fires... The engine compartment is full of ignition sources... hot manifolds, ignition wires/coils/etc... Very dangerous. Plus as I mentioned before, if you have a crack on the underside of your intake, you won't find it without a smoke machine.

Edit: the "right" way is to do it with propane. Propane dissipates quickly and leaves no flammable liquids behind. You still run the risk of explosions, but at least you won't burn your car down.

[This message has been edited by ryan.hess (edited 06-27-2010).]

Propane being heavier than air will collect in places like injector wells etc..
Just as dangerous as carb cleaner.

So I built this contraption today in hopes of finding the vacum leak on my 4.9. Called my dad over to help and to say the least he was skeptical but he's always up for trying something. We got it built fairly easily and attempted to hook up to my stock aircleaner (4.9 Caddy's is oval shaped) and thought we had a good fit but tthe real issue was the air cleaner doesn't sit completely tight (on my car to many hoses in the way) on the throttle body. But we kept pushing on. The only issue I really had was I couldn't keep the rag lit, every time I thought I had it going good and put the lid on it went out.......but boy did it produce smoke. In the end it leaked to much around the throttle body to really do us any good so we went about looking at all the hoses manually and believe we have found the culprit....a couple of bucks in new hose and the car runs way smoother now.

Now the best comment about the whole thing came from my Dad...."You better keep that thing as it works pretty slick" So kudos and positives for showing us this idea!!!

Here's pics of mine:




Dan

quote Originally posted by DanFiero: The only issue I really had was I couldn't keep the rag lit, every time I thought I had it going good and put the lid on it went out.......but boy did it produce smoke.

That's the point!

Glad it worked out for you!

quote Originally posted by ryan.hess: That's the point! Glad it worked out for you!

Except every time it went out it stopped producing smoke. But as I said we got it done and I thank you for that!!!!!!

quote Originally posted by ryan.hess: Make sure the pressure regulator is set LOW (5psi). If you are using a 12v car pump it will probably be fine as-is.

You mentioned 5 PSI is OK, but what PSI range would you recommend for leak testing?

I ask because I'd think that with too little pressure, you couldn't reliably identify a leak, but with too much pressure, you could actually create one, could you not, so what PSI range would you recommend for leak testing?

quote Originally posted by DanFiero: Except every time it went out it stopped producing smoke. But as I said we got it done and I thank you for that!!!!!!

ahh... Did you turn the air on quickly after installing the lid? Some rags may work better than others. Bee keepers use burlap in their smokers... I think a loosely woven fabric is probably better than 1000 thread count sheets.

quote Originally posted by project34: You mentioned 5 PSI is OK, but what PSI range would you recommend for leak testing? I ask because I'd think that with too little pressure, you couldn't reliably identify a leak, but with too much pressure, you could actually create one, could you not, so what PSI range would you recommend for leak testing?

Well, you want to look at flow more than pressure... You want a steady flow of smoke. Too high of a pressure will just pop the top off the can, so you shouldn't have to worry about causing leaks. With the blow gun I have, anything up to 20psi will work fine, BUT for me, the restriction is the blow gun. If I put a air fitting on the can directly, 10psi would pop the top off, since there would be 200lbs pushing up on the can lid.

Imagine a person breathing out - that's the kind of flow of smoke that you want. Use whatever PSI it takes to get there.

BTW, there should be very little pressure at the outlet, just because due to valve overlap, ring sealing, etc, there isn't really an opportunity to create pressure on the engine side.

[This message has been edited by ryan.hess (edited 07-03-2010).]

Instead of burning socks or rags, you could toss a small smoke-bomb in there. Just an idea, considering it's "that time of year".

quote Originally posted by Blacktree: Instead of burning socks or rags, you could toss a small smoke-bomb in there. Just an idea, considering it's "that time of year".

Smoke bomb and hand operated bellows and connect direct to the plenum?

http://chemistry.about.com/...nts/ss/smokebomb.htm and http://www.amazon.com/gp/pr...p=1789&creative=9325

[This message has been edited by User00013170 (edited 07-04-2010).]

quote Originally posted by User00013170: Smoke bomb and hand operated bellows and connect direct to the plenum? http://chemistry.about.com/...nts/ss/smokebomb.htm and http://www.amazon.com/gp/pr...p=1789&creative=9325

KNO3 and sucrose burn at about 3000 degrees. Be careful that your paint can doesn't melt...

I don't know why everyone is so adverse to using a cotton rag......

Built this yesturday, used it today. Leak found in about 2 seconds. Yesterday I used a full can of carb cleaner to no avail.
EGR shaft seal burned up. diaphram still good. About time I found this link.

Tip DON'T buy a 1 Gallon Can. Lid fails at 5psi. use the small one. less surface area to push on.
Materials used
1 Gal can (will be getting the smaller one soon)
extra length of air hose.
Two hose repair double barbs.
one 2" Rubber pipe cap to attach to TB
one air hose barb to attach to pipe cap at TB.
JB Weld to seal holes that barb fittings go into can.
Hose clamps
Blow Gun with barbed tip.


Stu

[This message has been edited by DIY_Stu (edited 03-18-2011).]

quote Originally posted by DIY_Stu: Built this yesturday, used it today. Leak found in about 2 seconds. Yesterday I used a full can of carb cleaner to no avail. EGR shaft seal burned up. diaphram still good. About time I found this link.

Cool! Glad it worked out so well for you! I've tried carb cleaner too, it finds leaks big enough to suck the liquid in and change the idle..... if you have lots of small leaks, or small leaks that are spaced far apart, you'll never find 'em without smoke.