ok so first of all i heard this noise before but only once on my truck however its now consistent. The "noise" sounds like a firecracker going off every 2 sec or less. it comes from somewhere around the catalytic converter all the way by the end of the exhaust. I am a noobie with cars but not to the point i really dont know what im doing so i took on the task doing the spark plugs and wires myself. I did them 1 by 1, i did the gap at around .040 (felt pretty loose tho on the gap ring thingy) even tho on my truck it says it should be at .035. I also Did the wires correctly for sure.

Oh another thing i did was i got an used sensor that controls the air flow i guess from a junk yard (the one right behind the two vents underneath the air-filter) and i also cleaned it and put it in.

the truck seems to run better, starts better and doesn't idle so high anymore like it did before.


Im sorry if im all over the place with trying to explain whats going on with my truck but im tired so please excuse me if you have to read this twice

OH another thing, i let it run a little longer to actually determine where the noise is coming from and after i turned of the truck a little misty smoke came from behind the engine inside of the engine bay

 

a sharp snapping sound is likely a spark wire jumping to ground.

check that your plug wires are on the plugs.
not burned on the exhaust manifold.
boots pushed on the plugs all the way.
distributor cap seated properly and not cracked.

check it at night when its good and dark.
spark jumping from a wire or plug should be a pretty blue show.

 

just checked everything, everything is nice and tight and snapped in, no blue sparks. it seems to come somewhere in the area of the trans and catalytic converter and its kinda louder than a fire cracker (doesn't sound like a snap sound more like a bang sound kinda like taking a hammer and banging it against solid metal) im bad at explaining sounds >.<

 

What is the brand and part number of plug you are running?

 

autolite 3924 and xact spark plug wires

 

Your CAT is probably toast.

 

was actually thinking that, but why now? right after i changed the plugs and wires.....

 

Get under your ride and bang on the cat and see if it rattles, if it does then its shot.

 

i went and checked the wires once again (for the 5th time) and finally i pin pointed the pop corn sound that was coming from my truck. the reason behind it was that i somehow switched two wire plug wires around. all is well now.

 

good deal.