Hissing and popping from the motor?

On my 2001 Jeep Wrangler 4.0 when I'm in neutral I hear a missing and a popping from the motor what do you think it might be

 

When was the last time the plugs/coils were changed?
Maybe a clogged fuel injector?
Though I would imagine you would get a Check Engine light with those....

 

Not sure what you mean by hissing. This to me usually means a vacuum leak. Not sure about the popping noise. Fuel injectors can make a ticking sound. If as Prerunner1982 is saying could be wires if you are hearing an arcing sound. Could you narrow the location down a little more. You can use electronic headphones or the standard heater hose a couple of feet long. Put to your ear and move around the engine to locate the noise or the general area of the sound. Does this happen ( hissing) when your foot is on the brake pedal? As you can see there is a lot to look at so any extra info would help me to help you look at the correct area. Do a visual inspection of the engine to see if you notice anything out of the ordinary. Or if you just had recently done any work.

 

I'm thinking I'm going to change my coil pack an plugs first think its the original pack . check engine lo ight is on , said one cylinder miss fireing

 

Sounds like you might have a bad fuel injector. Did it tell you which cylinder it is? If so try switching 2 injectors and see if the problem moves to a new cylinder. A while back we had a similar write up in the forums and it was a bad injector.

 

Thanks will do