When I get on the throttle from about 1500-2800 rpms, while the motor is under a load, I get a ticking/hissing sound that is very similar to the way an old worn motor sounds when it has leaky head or exhaust gaskets or it is missing/down a cylinder or two. However, as soon as I lay off the throttle, it goes away. While parked or sitting still, I can rev motor and it sounds awesome, no noise or anything. Sounds like it should. While moving and under load, the motor feels strong, nice throttle response etc. I have checked all the wires, plugs, installed new O2 sensors etc....noise is still there. My mechanic is thinking it could be a CV joint. However it doesn't make the noise while turning, which is usually the tell tale sign of a CV joint going out. He may be right, but he was puzzled as well. Could it be the front Prop Shaft U joints?? Or is it known to be the CV joints???

I will add that there is no pronounced vibration associated with this. At least I haven't noticed it, but I wasn't looking for it though. I will need to go pick it up from mechanic and go see if there is a vibration.

Anyone have a similar experience?

 

Just a thought, what octane gas are you using? this kind of sounds like engine knock, or preignition. Check if you have any knock codes on either or both banks.

 

There are no codes.

When I first got it, I unknowingly filled it up with 87, however I went through that tank and I recently filled it up with 91 Non Ethanol, and have since burned about 1/4 tank. It sounds the same and hasn't changed at all.

 

Ok, update. New O2 sensors, 91 octane non ethanol fuel. Also found both SAI valves were not bolted down and were just flopping around. Fixed those. It sounded better initially, but the 2nd time I drove it it sounds just like it did before, except it isn't hissing anymore. Now it is more of a deeper rumble type sound. I made a video. The best audio is towards the end. You can hear me getting on and off the throttle.

 

I have a similar noise when underload. It's especially noticeable when getting on the highway. Mine's not as deep as yours, more of a clicking sounds.

I can rev in park all day with no noise.

 

Mine sounds awesome in Park/Neutral. No hint whatsoever of a motor issue. No noises or hisses, or tick, or knocks, just nice V8 revving sound. Which is why I think it has to be exhaust related. However, I'm no expert.

 

The one thing that throws me off about it being an exhaust issue, is why doesn't it do it while in Park/Neutral???

 

Try some 93 in it and see if it goes away then.

 

I will, it is almost time to go fill the bitch up.

 

Sounds like an exhaust leak to me, maybe at one of the muffler flanges. Are they tight?