engine harshness at high revs

m4a1mustang · 06-30-2009, 03:09 PM

Quote:

Originally Posted by VTalumni

So, the problem must be related to the engine since it is noticeable in both the 6MT and 7AM (I know more in the 6MT but that doesnt matter).

Was this problem noticed in the 350z? Someone mentioned the VQ35DE was smooth. I am not familiar with engine names, but is that the 350z engine?

To me, the problem seems like its related to the VVEL. Do the vibrations increase gradually as you rev higher or is it an instant thing? Has anyone driven a Honda with VTEC? VTEC kicks in full force at a certain rpm. Its like a whole nother engine. The intake seems 17 times louder than before VTEC kicks in and the whole car becomes harsher. Does it seem something like that? If so and the vibrations really kick in all at once at a certain rpm, then we can confirm that it is something related to the VVEL. If not, maybe it is an imbalance in the crankshaft or camshaft, something rotating.

It's really a gradual thing. It gets worse as you go up in revs. It's nothing like the VTEC transition where at a given RPM *bam* you have a new engine.

VVEL may or may not have something to do with it, but I'd venture to guess that it probably isn't the root cause. It's probably just how the engine naturally behaves and we just have to deal with it. It's definitely wierd, though, because it doesn't feel right when you drive the car hard... but it probably is right. Just have to get used to it I guess.

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