locating vacuum leak with smoke?

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baja1

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numerous youtube video's DIY smoke pumps, anyone actually tried this?
cold engine starts at 1000rpm creeps up to 1500-1900 rpms,warm engine starts immediately 1500 rpm. no CEL's runs fine just this high idle.
I've read page after page but can't come up with a cure....this smoke idea sounds promising!
(i've search high and low, cleaned MAF, cleaned TB, the idle sensor under it....)

oops sorry.....'97 4WD
 
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I have not done the smoke method. I have used wd 40. Listen for the change in engine rpm. I have also used a hand activated vacuum pump. A 97' would be subject to dry rot. The entire soft line would be suspect.

One time on a Dodge Diesel I used small zip ties at every soft line location to verify the connection. Have you used an actual vacuum gauge while running? Verify the easy stuff before going down the rabbit hole.
 
I have seen on youtube where people blow cigar smoke into the plenum to find vacuum leaks....haven't tried it.

I have used a smoke machine to find evap leaks before...it's the go to method for that problem. It does work but the equipment is very expensive ($800+) & I don't own one. It would work for a vaccuum leak as well but I usually spray brake clean on the suspect areas location by location with the engine running and listen for the engine to bog or sputter a bit indicating a leak. Careful as brake clean is very combustible...the prescribed method is to use propane which is less dangerous in the small quantities required for this procedure but the brake clean is always handy.

Good luck,

Buckaroo
 
Research the web. You can make a smoke machine for cheap.

I use the propane method. Motor will rev up when propane is sucked into the vacuum leak.
 
baja1 said:
numerous youtube video's DIY smoke pumps, anyone actually tried this?

....this smoke idea sounds promising!
Click to expand...

Diy smoke machine worked well. I didn't see smoke escape from the very small evap leak I had but when I tested it on medium to to large leak (I simulated a leak by loosening a hose) I could see the smoke escaping. I was outside and it was sunny and a little windy which may be why I didn't see the smoke escape from the small leak I had.

Highly recommend making one because in my limited experience, it is not uncommon to have to test multiple times or locations to find a leak especially if it's a small leak. This would mean having to repeatedly take it to a shop to find a leak if it wasn't identified the first time around.
 
JayRolla said:
I use the propane method. Motor will rev up when propane is sucked into the vacuum leak.
Click to expand...

+1

Easy, clean, effective.

Spray products work pretty well too, but can be a bit more messy. WD-40 is a good choice. I don't like carb cleaner and brake cleaner for this -- they're kinda harsh on rubber parts.
 
I built one of the smoke machines from watching a combination of video, probably cost me around $30 and a few hours of time. I added some fluorescent oil tracer dye to the baby oil in order to add an alternate way to find the leak after turning the smoke off.

I used it to locate a evap system leak at the tank (P0440, P0446 codes). I should have used it a lot sooner, would have saved me time, money and probably a fix-it ticket.
 
txzaphod said:
I built one of the smoke machines from watching a combination of video, probably cost me around $30 and a few hours of time. I added some fluorescent oil tracer dye to the baby oil in order to add an alternate way to find the leak after turning the smoke off.

I used it to locate a evap system leak at the tank (P0440, P0446 codes). I should have used it a lot sooner, would have saved me time, money and probably a fix-it ticket.
Click to expand...

30 bucks!? can you link some of the videos you looked at or describe your method?
 
Usually you would get a lean code with a vacuum leak.

Did it get worse when you cleaned your throttle body?

I would check your TB and make sure it is closing correctly.
 
I had a lean code and did the cigar test myself. Saw the smoke coming from between the manifold and VC but couldnt pinpoint.
Went to a friend’s and used his fancyass smoke machine and had the same result just more smoke.

Still could not pinpoint so i just replaced the manifold gasket and injector seals and it seemed to fix mine.


Sent from my iPhone using Tapatalk
 
The propane method has always worked for me on the 4Runner. On my son's Mercedes c300 I had to graduate to a DIY smoke system. An empty paint can, a few nipples, some vinyl hose, and regulated air from my compressor--add a few charcoal briquets and cardboard, and voilá...smoke machine. The smoke revealed a leak in a place that would have been very hard to get to with the propane. That's the big advantage of the smoke. Wherever the leak is, you will see it. With the propane, you only see it if you get the torch close to the place where it is leaking. The 4Runner system is pretty accessible compared to more complex, crammed in cars like the Mercedes.
 
TheDurk said:
The propane method has always worked for me on the 4Runner.
Click to expand...

A lot of people use that method but I can't hear the engine change much when there is a really small vacuum leak of the kind that show just one lean code that is intermittent.

Smoke at least is pushed out at pressure.
I don't know the pressure where I'd guess it to be a psi or two.
That might find a hose leak.

Do the smoke machines work when the engine is off or only when it's on?
 
JamieG said:
A lot of people use that method but I can't hear the engine change much when there is a really small vacuum leak of the kind that show just one lean code that is intermittent.

Smoke at least is pushed out at pressure.
I don't know the pressure where I'd guess it to be a psi or two.
That might find a hose leak.

Do the smoke machines work when the engine is off or only when it's on?
Click to expand...

No, you want engine off. Otherwise the smoke gets sucked into the engine. For the smoke to escape, you need positive pressure in the manifold.
 
TheDurk said:
No, you want engine off. Otherwise the smoke gets sucked into the engine. For the smoke to escape, you need positive pressure in the manifold.
Click to expand...

Thanks. I bought a "poor boy smoke machine" during the post halloween sale, which is a gallon of the smoke liquid and the machine at Walmart.

I need to adapt it for the engine to find leaks but I don't have any leaks yet so I was mostly curious for when I do have leaks.

At this age of the car, seems to me we should replace all the rubber.
Is there a kit for that?
 
JamieG said:
Thanks. I bought a "poor boy smoke machine" during the post halloween sale, which is a gallon of the smoke liquid and the machine at Walmart.

I need to adapt it for the engine to find leaks but I don't have any leaks yet so I was mostly curious for when I do have leaks.

At this age of the car, seems to me we should replace all the rubber.
Is there a kit for that?
Click to expand...

That's a great idea!
 
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