[Unknown User]

when i let go of the accelerator pedal from around 3500 RPMs the engine makes a buzzing sort of sound at exactly 3100 RPMs it only occurs at deseleration.could that be the timing chain? thanks

 

[240Z Turbo]

That sounds kind of odd. There is alot of vibration on deceleration, maybe something in your engine compartment is a little loose and the vibrations caused by the engine under decel are the same vibrations as the loose parts resonant frequency. Simply put the part will only be in resonance by vibrations caused by 3100 rpm under decel. Don't answers like this make life much easier?

> when i let go of the accelerator pedal from
> around 3500 RPMs the engine makes a buzzing
> sort of sound at exactly 3100 RPMs it only
> occurs at deseleration.could that be the
> timing chain? thanks

 

[Ron]

yes I agree, something is loose but tight enough so that during a certain
stress point during decell, a vibration will occur.

 

[Unknown User]

I think you guys are right it also happens at around 1500 RPMs roughly the half of that 3100
it's probably my exaust manifold i crunched my exaust going over a wall of a speed bump(exuse my spelling it's 3am here)

 

[Yannick]

> I think you guys are right it also happens
> at around 1500 RPMs roughly the half of that
> 3100
> it's probably my exaust manifold i crunched
> my exaust going over a wall of a speed
> bump(exuse my spelling it's 3am here)

I have the same problem. but my exaust manifold is n't crunched. The only difference is that the weird vibrations are occuring from 3100 to 4500. Does anybody else has a solution...