The reason for MIVEC not engaging at low rpm is to enhance bottom end, which it does. Also, if it engages at 4500 rpm then that allows more fuel efficient highway cruising since you're likely below the engagement point now.

If the noise doesn't occur when you are easing it, then it means you are not hammering into the rpm that coincides with the mechanical vibration, so the sympathetic resonance of the part making the noise doesn't get excited as severely and you don't really hear it vibrating. It does make sense its something like a heat shield or other loose bit being excited to resonate at a certain rpm. Look closer at the sheet metal shields near the exhaust.

 

What metal sheet are you guys talking about? It sounds like its coming from the intake area. I'm just hoping that its not something in the engine. Will be checking everything out tomorrow to make sure. Its going on the lift will check the crossmember too for those who mentioned it. hopefully itll be good news.

 

Just remembered he has an OBX header, no heat shield on his car.

Possible cracks in the header's welding?

 

So...

Any updates on this? I'd like to know if you found anything out. I'm quite curious about this issue lol.

Thanks!

 

Sorry for the late reply. The rattle is gone as far as I can tell. I did dump a can of RESTORE in the car and then got an oil change. I usually use synthetic but I think the guy at the garage put regular oil in it. Don't know if that could have made the differance. Im curious on what type of oil you guys are running.

 

amsoil signature 10w30

 

castrol syntec 5W20 (the gold coloured container)

 

Using AMS oil now going back to Castrol Syntec.