SharkSkin

Idle speed should change. Were you using one of those tiny hand torches or something more along the lines of the pic below(with or without the hose)? You have to hold the tip right up against the seam that you are checking...

RichS 1986928

Dave,
Yes, I used the same size propane bottle, it has a regular plumbing type tip on it.
It definitely is releasing as much propane as your set up.

I held it right to the MAF with No change... what do you hear when you do it? Idle fluctuation?

Thanks,
Rich

SharkSkin

I'd expect the idle to increase 50-100 RPM when you get to the leak, or if it were running rough it would smooth out. It occurred to me that all of the cars I've tried this on were purely mechanical systems; different carb variations, and CIS injection. It could be that the reason you're not seeing the change is the system is adapting to different mixture changes, or the leak is just too big to notice a difference. If it's a really big leak you might be able to find it with a 3-4 foot section of fuel line or vac hose -- put one end to your ear and the other end near any/all seals/hose ends, listen for a sucking sound...

You might try pinching or plugging the lines close to the manifold(only pinch if they are in great shape and very pliable). Brake booster line is one possible suspect, but you would have a very hard brake pedal if the brake booster was leaking. It could also be a cracked vacuum tee, etc.

Mike Frye

Dave,

One other possibility: More than one leak.

In JHowell's case, I don't think he's very confident about the prior maintenance, I don't know about Rich but for me, I'm sure there's a laundry list of leakage. Would the propane affect the idle if there were multiple leaks and you were only putting the gas to one of them?

SharkSkin

Yes, multiple leaks would reduce the effectiveness of this test, or any other except maybe the innertube or smoke tests.

JHowell37

I like the way you put that. I'm in the middle of changing the timing belt right and the mess from all the oil that's baked on the engine and accessories made me first wonder if some overzealous person didn't spray undercoating on the engine as well.

I took off the timing belt tensioner and the rubber boot just crumbled. But the timing belt looked very good. So I'll give all of the PO's that much credit.

RichS 1986928

I'm going to try unplugging a vacum line and letting it suck in the propane.
That will hopefully show me if the test does anything to idle.

Mike Frye

JHowell,

Thank heaven for small favors. Are you going to do the TB anyway?

I gotta say, you're tearing into that thing like a madman. Every time I go online you've got another project going, brakes, TB, body work, vacuum lines (and some nice looking work on the intake manifold). So far I've got the ODO gear replaced, replaced all fluids and a tune-up. I'm stuck on getting mine through inspection and you've got yourself halfway to a new engine.

BTW- I got mine to idle properly by adjusting the idle screw . I'd rather be lucky than good.

Any luck on the fast/fluctuating idle yet? Maybe someone else has another suggestion?

JHowell37

There's a huge difference between my car and yours. Your car doesn't look like it's fresh off the set of a Mad Max movie. Mine is the only 928 I've even sat in. The fastet I've driven it is about 35-40MPH. So you can imagine how frustrating it can be at times. It's like being in a celibate marriage with a Victoria's Secret supermodel.