how to find vacuam leaks

[shocker998md]

So ive replaced all of the vacuam lines on the car with new ones, and zip tied all of them as well. Some times the car will idle VERY high, like 1800rpms and this is after its warmed up and all of that good stuff. My tps and iac are good, so im thinking vacuam leak. Now i go out today to poke around at this and what do you know, its not doing it. Ive got a TT chip and the car normaly idles fine, but sometimes its idling high. Any body have some ideas? And what is a good way to check vacuam leaks? I want to say you can spray throttle body clean around gasket areas and the motor will stumble a bit, but i may be wrong. Any input would be great.
Kenny

 

[Lobsterbak]

spraying starter fluid around a bad gasket should cause the engine to rev a little bit higher...showing you a vac. leak :smile:

 

[DailyDrifter]

Pull your IAC out and see if there is any cabon buildup in there. The plunger may be sticking.

 

[regan j]

Good way to find a leak

Find someone who smokes and have them blow smoke into the suspected line and ALAKAZAM or ABACADABRA. Your choice. Good Luck.

 

[datant69]

old school way

i've heard of using a hose small enough to insert into your ear ( not all the way but so you can hear it ) and running it along your vaccum lines. I haven't ever done this but saw a buddy do this and a few mechanics buddies back in the day swear to using this method. Just what i've heard, it may work it may be BS.

 

[pajo]

hose

the hose in ear trick usualy works with finding small exhaust leak but to find a vacoom leak I use just plain water in a spray bottle so that way you dont have to worry anything catching on fire while you are spraying..2 cents worth of smarts..:biggrin:

 

[bison]

Nothing beats the smoke for vacuum leaks. If your near CT and want the smoke PM me.

 

[GSTOY]

X2 IAC could be sticking.

Things I would also check...

vacume block gasket
cracked vacume block
doghouse gasket
throttle plate seals...doubtful
IAC block on the bottom of the throttle body, not the o-ring seal that that's on the end of the IAC motor that screws in
steel vac lines rusted?

I do remember that if you disconnect the computer or install a new TT chip, Eric states the the idle will go high because the computer doesn't know the position of the IAC, but you state that IAC # is correct

Might connect a vac guage and see what your readings are when you are and are not having this problem

Don't give up...:smile:
Steve

 

[Turbo1dr]

If the engine is revving up to 1800 then you should be able to hear....WITHOUT DOUBT... a very large vacuum leak...IF it's a vacuum leak.

i've heard of using a hose small enough to insert into your ear ( not all the way but so you can hear it ) and running it along your vaccum lines. I haven't ever done this but saw a buddy do this and a few mechanics buddies back in the day swear to using this method. Just what i've heard, it may work it may be BS.

I still use this method to find vacuum leaks. It works just fine! A 5/8" heater hose works good. You can also pinpoint exhaust leaks like this too!

 

[turbo nasty]

I had 3 ports on teh intake gaskets seeping, all the fittings on teh alun vac block leaking, and egr itselfleaking. Itried , brake clean,propane, ether, h2o and teh motor never changed at idle or high wnhen sprayed.
I had to pluu therocker shafts so all valves were closed and then psi the intake to the turbo and found all teh above plus my uppipe was leaking at 18 psi and and resealing at 16.
I used a soup can with duct tape wrapped around it and then poped a valve stem in the bottom will rtv arount it. It was a rig but work. Buickgn.com has a real nice on though