Hard acceleration noise

When i step heavy on the gas of my 00 3.4L 5 speed, under load, it sounds like someone is shaking a plastic cup full of bb's on the other side of my firewall. When my foot gets all the way to full throttle, it stops. If you let up any, it comes back. Not a consistent noise like a knock, it's like a random clatter. Not rhythmic. Any ideas?

 

detonation?

 

X2

Try a tank of premium gas and see if it stops. If it does, maybe you have a bad knock sensor?

 

I figured if it was detonation, it would be more rhythmic, this sounds totally random and uneven. However i never noticed it until today, and I filled up with 87 from a station out of my neighborhood this morning. What else can cause detonation? I just bought the truck, havent checked the plugs yet.

 

Piston slap, bad fuel, or maybe a bad cat? Cats can sound like bb's when broken.

 

Sounds like it's right on the other side of the firewall from me, not below. I am tired of finding things on this truck I just bought, already have bad input bearing and a torn cv boot!

 

Blocked EGR passages or bad EGR valve can cause detonation, also lean fuel mixture, timing too far advanced. Don't know how smart the 3.4's computer is, but I would think that timing is non adjustable, and I am pretty sure there is a knock sensor on that engine. Bottom line is that the sensor should detect the detonation almost as fast as you can hear it. The computer should be reacting to the knock sensor and pulling timing out to stop it. Maybe someone on here knows the specifics on that engine.

I have personally had a blocked egr passage on a Toyota 22r engine. The egr valve would cause the engine to run rough when manually activated at idle, but the actual passage was blocked except for a hole the size of a pencil lead. Took awhile to track down, but completely fixed the constant pinging I was having.

 

Would the ping stop at full throttle though? MY knocking always stops at full throttle, then comes back when you let up some.

 

I've had two different trucks that had a ping issue. A Dodge Dakota with 3.9 V6 and a Toyota 4x4 with 22R four banger. They both would ping at 3/4 throttle, but not at full throttle.

 

Well that's probably my issue, have not heard it before today, had it almost a week. Wonder if I got some crummy gas?