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Old 09-15-2007, 10:40 AM
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Default What's the safest way to look for vacuum leaks?

I'm still trying to chase down my low idle and lean condition issues in the 993. About the only things left to do are cleaning injectors or rebuilding them and doing a diligent search for vacuum leaks. Can I just spray starter fluid around the top of the engine with it running and look for a bump in idle speed? Or should I use a gas torch with no flame? This is driving me nuts.
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Old 09-15-2007, 10:59 AM
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The unlit propane torch method is safer and should help you localize the leak easier than starter fluid. This is the preferred method, for sure, since propane will disperse more quickly than starter fluid and if it does get lit a quick "whump" burns it all up with no damage other than some burned off body hair.

Having said that, if you have a pretty good idea where the leak is and just want to confirm, then starter fluid used in small quantities is OK.

Whichever you decide to use, be sure to wear eye protection!!!
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Old 09-15-2007, 12:03 PM
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If you are friendly with somebody in a shop, a smoke machine works great.
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Old 09-15-2007, 12:44 PM
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x2 on the smoke machine
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Old 09-15-2007, 02:02 PM
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Is a smoke machine something I can pick up cheaply somewhere and DIY this?
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Old 09-15-2007, 02:19 PM
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You can DIY but picking one up cheep isn't gonna happen. The one we have at work was $4k an dthat didn't include the tank for the nitrogen.
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Old 09-15-2007, 02:25 PM
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I guess blowing cigarette smoke into the intake ain't gonna cut it, eh? Ok, Ill go grab a nozzle for my torch that doesn't self-ignite.
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Old 09-16-2007, 07:25 PM
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I used a torch today with a 4' hose. No dice. I didn't get any bump in idle at all. What next? Starter fluid?
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Old 09-16-2007, 10:49 PM
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RL, my car idles *exactly* the same as yours. As do a lot of other v-ram 993's. I don't think you have a vacuum leak.
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Old 09-16-2007, 11:21 PM
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Is you idle a rock solid 500 rpms? I have a recurring CEL and the code is for a lean right bank. I think my temps are a tad high and fuel economy has been a little too good.
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