Checking for vacuum leaks... Propane didn't work!
 

I tried the propane method today and it didn't work. I pulled out the PCV line from the intake and opened the propane torch valve all the way, put it right up against the PCV port on the intake where it was sucking in quite a bit of air, and nothing. Engine didn't change speed, sounded exactly the same. Am I doing this wrong? Yes propane was coming out, lots of it.

What else will work?

smoke generator is best:


http://www.fiero.nl/forum/Forum1/HTML/081547.html

A really cheap smoke generator is otherwise known as a cigar!

Any other ideas? I don't have a smoke generator, but I suppose I could take up smoking.

Why didn't propane work? I thought it was supposed to be a good way to do it. What about brake cleaner or starter fluid?

Use starting fluid. Just spray in a certain area and listen if it revs up. I had a 89 coupe 5.0 and got used to this once a week.

X2 with starting fluid, or u can use carb cleaner/ electrical contact cleaner/ flammable brake parts cleaner. My personal favorite is brake parts cleaner that's flammable. Also drops bees in a hot second. The little red nozzle straw comes in handy for isolating the spray. One other perk is it will clean ur heads nicely too.

Could brake/carb cleaner damage the intake seals?

nope, maybe if they were totally immersed in it for multiple days at a time but out of a spray can it will evaporate too quickly.

Ok, I'll try that.

And can someone tell me why propane didn't work?

You need to defeat the IAC, if you're chasing a lean problem
but the idle speed is right. Otherwise IAC will act faster than
you can hear the motor drop RPM.

If the motor is overfueled with an air leak then more fuel
may not make much difference. Stoich or lean, big diff.

I have no idea if it's lean, rich, or stoich. Idle speed is right on, but the idle hangs if start moving. Could it be the throttle cracker? And there is some ticking noise. It could be my tune, but I want to rule out what I can.

I'm not going to comment on the possible vacuum leak as there appears to be some backstory that I'm unaware of.

I WILL HOWEVER comment on the use of brake cleaner of any type for locating vacuum leaks. DO NOT COMBUST BRAKE CLEANER!!!!!!!!!!

Chlorine is found in ALL brake cleaners (even the ones that are "chlorine free"). Combine that with carbon monoxide (a combustion byproduct) and then put both through a catalyst and you get PHOSGENE gas.

USE CARB CLEANER

I always just used WD40 and watched for the exaust smoke.

smoke/cheap fog machine.

I think that's actually a pretty safe option. Way back in the days of distributors, I actually caught a 3.0L For Taurus engine on fire because the brakeleen trick caught on fire. Nothing happened and I had an extinguisher close by, but still. Never trusted that diagnosis idea since.

Tried propane again at hot idle with the IAC unplugged, and same result, no noticeable change in RPM.

you're supposed to use the propane the same way you would use a spray. you move it around gasket areas or anywhere else air could sneak in. if you unplug the IAC, the computer wont be able to adjust idle speed, so you'll get a truer reading. just move the probe around different things until the RPM increases. do you have like a bank 1/bank 2 lean code or something?