i have a '03 manual and recently changed the trans fluid to redline mt. Whenever I accelerate, lets say to 4k, i let off the throttle and the rpms start to drop as soon as the needle hits around 2.2k rpm there is a loud sound which continues till 2k rpm then the sound disappears.

The sound is very brief or rather not very audible at all during acceleration only once i left off the throttle. This happens in every gear at that specified rpm range. The sound seems like its coming from where the glove compartment would be in a normal car. (in front of the passenger)

Can anyone advise or shed some insight

I checked the trans fill/drain plug everything is good still no leaks

 

Very likely a bushing in the suspension, and nothing to do with the fluid change.

 

It sounds almost metallic, although my mechanical knowledge is limited it doesn't sound like a suspension issue. If it is, why would it only make the noise between a certain rpm

 

A metallic sound could be one of the pulleys on the front of the engine. Belt idler or tensioner, alternator bearing, etc. Stick your head in there while someone revs the engine for you, but watch out for moving parts.

 

I have a similar noise (at least I have a metallic noise on deceleration between 2500 and 1200 rpm in all gears). It started after the clutch was replaced. The exhaust was dropped and after I got the car back it had a leak. Left it with the dealer to fix and when I got it back it had the noise. Wasn't that bad at first so I didn't take it back again, but it's got worse.


I believe it's a heat shield vibrating against the pipe. Haven't had an opportunity to put it up on stands to check.

 

very possible , when i had aftermarket cats it was close to the shield and would cause it to vibrate

 

i also recently reverted back to a oem exhaust but i removed the heat shield due to excessive vibration noise

 

maybe the cat honeycomb breaking apart... man its hard to say over the internet. bribe a buddy with beer or take it to nissan to get properly diagnosed

 

I've been meaning to get the cats checked cause if I gun it I get a foul smell in the cabin. So could it be a probable car? Just strange to me how it only happens in that very specific narrow rpm range

 

here is what i would do..... get all four corners up in the air, bribe said semi drunk buddy to get under the car by the cats and see if hears it... may or may not without the resistance on the drivetrain and motor being up in the air... or just knock on them with you hand to see if you hear any rattles