Intake / Engine / Unmetered Air Leaks - Smoke testing?

Hello there,
Just wondering if anyone know of any "poor man's" techniques of detecting vacuum/engine/intake air leaks by forcing smoke or compressed
air into an engine. There is equipment on the market but its well over the $1000 mark.
Plumber's smoke candles only cost about $7, but they leave residue. There needs to be a way to pressure feed the engine and passageways with the smoke for it to find the openings.
I can't get my idle below 1200 using the throttle stop screw, following the instructions on the sticker under the hood. I have plugged all of the vacuum taps on the intake one-by-one and altogether (except fuel pressure regulator, holds vacuum) and no difference in idle.
I am thinking injector O-rings, intake gaskets or something between the vane meter and combustion chamber is allowing extra air into the cylinders. Maybe even the head gasket since I have telltail signs of oil leakage on the block, just under the head.
Thoughts? I would love to find the source of this unmetered air. Thanks, Matt
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did you try the water bath or propane test?
--
- Yes, I'm a crusty old geezer curmudgeon.. deal with it! -

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Not yet, but check out this link, claims using an old inner tube and a bicycle pump works on a porsche 928. Got me thinking.
http://www.nichols.nu/tip367.htm
How effective is the propane test, been meaning to do it, just haven't had the chance. Never heard of the water bath, how does that work? Thanks, Matt
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opined in

Spray fine mist water over intake area with engine up to temp, if a hairline leak, engine will slow.
Have you tried with the MAF disconnected?
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It has a vane air meter, no MAF.
If I did this and the engine slowed down, not sure where I would start looking.
Thanks, Matt
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Probably the idle control solenoid is just bad. I'll assume it's a 4 cylinder 2.3 or a 1.6 in shall we say a Escort or turbo bird or is it a Mazda based vehicle? You mentioned the vane air flow meter, not many ford vehicles had it. That type of info is kind important.

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I have a new idle control solenoid that is only a few months old, no difference in engine behavior between that and the old one.
I capped off all vacuum taps to the intake except for the fuel regulator, which checks out with a vacuum pump. No change in idle speed.
Following the throttle stop adjustment steps on the underhood sticker yielded no joy either. I can't get the idle below 1200, which is why I want to test for any air leaks from the throttle body to the cylinders (gaskets, injector o-rings, throttle body).
I got a remanufactured vane meter and that cleared I think three of the codes the computer was throwing, now I only have a lean condition with codes 41 and 47.
16 is also present but I keep the throttle stop set incorrectly because if I didn't the engine would be idling at 2000 rpms.
It's a 1990 Escort GT 1.9 EFI HO, last of the 1st gen US models.
I can't wait to find out where the *&^^&%&^ 'ing extra air is coming from!!!
Thanks, Matt
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