strange vibration

[GruvyTune]

I have a turbocharged integra. Engine is stock.
When I have rev my engine and let go of the throttle, I get a shuddering and vibration. I can feel it transmitted into my turbo housing. Its not the turbo since it is not spooling up with just reving the car at rest and the car drives and accelerates just fine.

Any ideas of how to narrow down what is causing it? Anyone have something like this with their car?

thanks

[nov0798]

the turbo will spool some, to solve the problem quit revving the engine when there is no load

[GruvyTune]

but should it vibrate like that when coming off the throttle?
It happens when driving too when coming off then throttle and shifting into neutral.

[SlapSmak]

i have seen that with a stretched timing belt. engine vibrates, you can feel it in the back of your head. dont know if that is what is causing your problem, but on my wifes old GST same issue.

[GruvyTune]

funny how you mention that!!
I was looking at my timing belt thinking it looks a bit slack!

I just put it in a year ago (not even 7000miles.
Is that possibly the problem?

I will go and tighten it up today.

[ChillOutWayne]

did this happen before the turbo install? cause i dont have a turbo and i get a rattle around 3-4k rpms' adn it comes from underneath, right around my cat, but i removed all the heat shields, gutted the cat and replaced the header, no luck there

[GruvyTune]

It was the friggin manifold bolts!! Those damn locknuts came loose in only 1 day!!! I had to cut one off the other day because it was so tight and stripped.

Well I tightened them down real good this time. no more vibration