i have an 03 evo 8 with gsc cams, fp white turbo, gsc stroker kit and all hks intercooler/piping/bov tuned by cft. whenever i let off the accelerator pedal, the engine makes a noise and jumps a little, kind of rocks back and forth then stabilizes. at idle its fine and also during acceleration. the noise is hard to explain, its not a tick or a knock its almost like a low brrrrrrr noise with a deep rattling. i have no idea as to what it could be or where to begin to fix it. any help is deeply appreciated!

 

does it feel like its in your gear boxes? like diffs or possibly a boogered up drive line? or does it kick like its coming from the engine?

 

See if it does it in low rpm's vs high. Like 2nd @ 6k and 4th @ 2k.
It could be a mount starting to go. The motor is moving back and forth and you can start to feel it through the car.

 

try to find out when the noise is coming from. It could be coming from the gearbox/trans.

Does it happen in every gear?

Mine is an 03 and I sometimes get a purring noise just as I get off the throttle. But I don't get get that jerking back and forth you feel.

 

Its worse in the lower gears like 1st or 2nd but it does them in all gears. Its sounds like it might be coming from the gearbox, I think my synchros are going bad also, idk if that would affect it in that way also

 

I have this noise too. It drives perfectly fine.

It's only when decelerating in gear. As soon as I step on the throttle (even just a little) while the noise is there it goes away.

I'm guessing it just has to do with the load on the gears changing direction when on and off the throttle. Possible also input/output shaft play.

My best guess. I've had it. Had no issues with it. (it's that tight metallic vibration type noise, but you don't really feel any vibration)

 

Yea it drives fine I just didn't kno whether or not its something I should worry about, thanks