Along the same lines. I have found Propane works good too. I point the unlit torch around the area in question. Also no mess!
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It can fail to find some leaks but is otherwise OK if used with caution (ventilated space is wise!).

I suspect it wouldn't find a small leak in the hose buried under the intake in a 2000MY 3.0, yet you'd see there was a leak via OBD live data.

 

I use Throttle Body cleaner it is a lot safer.

Link http://www.jagrepair.com/images/Auto...otos/P0171.pdf