best way to find a vacuum leak?

[burnin240sx]

What is the best way to find a vacuum leak?

[NISTECH]

hook up a volt meter to you O2 sensor and watch the voltage as you lightly spray different areas of the intake, The reading should stay low near 0V till you hit the leak with brake clean or carb clean, once you hit it your voltage will spike up to around .8 to 1v

[mick]

Is starter fluid less damaging to rubber and useful for leak testing?

[W O T]

Use carb cleaner

[vancouverbc]

Im not so sure the voltage thing will work because the voltage at idle is already very high. ie it is already .8 . It is supposed to be high at idle . that is why they have the aiv for the s13's. the aiv is downstream of the o2 sensor so the o2 sensor will always be rich at idle.

im going to give it a try because spraying carb and watching rpm's did not work for me.

[W O T]

I dont "watch" rpms when spraying it, you can hear an audible difference

[mick]

Is it ok to spray carb cleaner and just leave it......or should I spray soap & water on the hoses afterward?

[W O T]

Carb cleaner / most engine cleaners are perfectly fine to spray and leave (altough spray and wipe gives a better appearance)

Its brake cleaner and you want to wipe off or avoid getting on your hoses etc, that s*** can EAT

[vancouverbc]

not sure about carb cleaner. hopefully, it evaporates fast. i think it is pretty similar to mineral spirits that is used to clean up paint. not rec'd for cleaning engines.

fsm says to race engine at 2000 rpm for 30 seconds to see if rpm drop indicating air leak. vacuum pumps are only 30 bucks . ill try and test to see if it picks up a open vacuum hose.

[terrible01]

how about just using air pressure and soapy water... pcv end cap with a valve stem in it, using that to introduce air at the maf. got to cap off the lines to the valve cover though...