when i have the gas peddal pushed in about 2/3 to the floor, i get a rattling noise in the engine compartment. i made sure everything's tight, but it's still there. i first thought it was something in the intake or cylinders, but it only makes the noise when the peddal is in that certain position. it doesn't matter what gear it's in, rpm's, or the speed. maybe a loose throttle cable?

 

do you have engine ping? does it rattle under load?

 

I actually have that same EXACT problem as was planning on asking this forum. Same scenario, only when the gas pedal is in that position, although I notice mine does it more often when I'm going up a hill when it's in third gear? Maybe not the same problem but its a loud rattling from under the hood for sure. Sorry I was no help but glad to hear someone else is experiencing this.

 

it's coming from under the hood. sounds like it is close to the firewall too.

 

I put my head by my cat, and my buddy rev'd the engine up. sounds like the cat might be bad. any opinions on new cat's? which is the better brand? i have headers to single cat, to muffler, split out of muffler to rear.

 

kick the crap out of the cat and see if it rattles.

 

i did that too. it rattles a little bit, but it gets worse when there's exhaust flowing through.

 

There are actually a lot of different situations in which you will hear that engine ping. For me, its mainly when the truck is in overdrive, and when not in O/D, going up hills. It is very annoying, to the point where I am wanting to get rid of the truck. Its going to die anyways, might as well look around now while it still moves. But back to your point, I thought it was the cat at first too, so I had it replaces, turns out that wasn't it. Try running some plus or premium gas and see if the sound decreases, if it does, you know its pinging. I'm not sure what the middle one is called, plus is coming to mind, but with that, it was reduced, and i would hear it only now and then. With premium, I did not hear it at all. It was glorious driving the truck around in premium; still had no power, but no noise either.

 

I just replaced my cracked tb with an oem ported to 50mm. i can hear the rattling noise in the tranny. i had it idling, then i went underneath and i could hear something in there. i need to rebuild it anyways, it's got 121k on it. any other ideas? thanks!

 

Doesn't the Plenum Gasket cause a ping.