I have recently changed out my spark plugs, wires, and coil pack. I also had a clogged fuel injector so I replaced that as well. When the engine is on I can hear a hissing noise which I believe to be a vacuum leak and I can smell gas. There is black soot coming out of the muffler. I am getting code P0172. I am insure how to diagnose a vacuum leak. Any help would be appreciated. Thanks!

 

Why year is your vehicle? Because you may have a vacuum leak and or a injection wire harness problem.

 

It is a 2005 Dodge Caravan SXT 3.3L. I have been talking with a service tech on justanswer.com and he says there is a TSB for this issue and to put the OEM spark plugs and wires in and have the computer updated to fix it. I am going to try that and see where it gets me.

 

If you decide to check for vacuum leaks you can use carb cleaner or propane from one of those small handheld torches.I prefer the propane because it doesn't make a mess like carb cleaner does.Start the vehicle and let it idle,open the valve slightly on torch so propane comes out,run the torch tip around every gasket,vacuum hose,and vacuum operated component.If using carb cleaner,just spray around every gasket,etc.Do while the engine is cold if using carb cleaner.If the engine idles up,down,or stalls while runnin the propane near every gasket,etc you have found your vacuum leak.The leak causes the propane to be drawn into the engine creating an idle change