oxblood!z28

i got an issue with my z theres a knocking sound coming from the engine and its evident up hills, but you dont hear anything when you give it gas in neutral. the dealership has worked on it and said it was carbon build up. I brought in to get fixed and they still haven't figured it out after 2 tries. Now there saying it could be carbon build up within the rings, but if that was case wouldn't you here it when you give it gas in neutral. and its also throwing a P0300 code. But it goes away from time to time then reappears again. if you guys could help out with some advice i'd appreciate it.

brianfromhawaii

iTrader: (3)

could be a rod bearing about to take a crap.

jimmyblue

iTrader: (11)

Is the knock "heavy" or "light"? Feel it in the body
sheet metal, or just hear it?

An exhaust leak is one load-dependent noise. See if
it shows up in drive on the foot-brake with a little
gas.

Exhaust banging is another thing that can show up
under load.

Pinging would usually be more of a "gurgle" but a
fuel starvation or injector imbalance problem might
make it more cylinder-specific and distinct. Some
other misfire problem could as well, intermittent
spark under load might jerk the motor enough to
make bucking and banging.

oxblood!z28

i hear it in the body..i dont feel it....it sounds like its coming from the right side of the engine. i tried your advice jimmyblue with the foot on the brake and gave it gas while in drive all i did was roast the tires....and I didn't hear anything.... sound just underloads....could it be the the speed adjuster located near the battery because thats were i hear the knocking....anymore advice?