I know of a guy on another car platform that had a very similar problem - supercharged setup, in the upper revs power just dropped off for no obvious reason. Turned out a plastic section of his intake was bending shut from the pressure at the upper RPMs, closing off the intake somewhat. I doubt that's your problem, but it's another thing to look for. Sounds like it has to be some sort of mechanical problem because anything tune-related that would cause that seems like it'd be fairly obvious to the tuner.

This would help us understand.

Coop

Will work on getting a chart Sorry didn't see your post earlier!

Hmm, that is very interesting, only reason I think it is software related is that it always happen 7100 rpm..Like the train is NEVER Late lol.

Sounds a lot like the SC belt is slipping to me. However, if it's at an exact RPM every time, I suppose that's less likely.

do you have a 7at or 6mt ??

if you have the 7At , you might have the same exact problem that I had for a complete year , no one was able to figure out what was the problem and it got worst by the time went

I had the luck of blowing my 7 AT at the drag strip and when they did the replacement they saw the flywheel which was badly cracked !!!

in the beginning when I noticied the problem it was at the beginning of winter , at that time we supposed it was some bad batch of winter gas.
but the problem never went away during the summer so we tried soo many thing.

by replacing the flywheel and tranny , I do not have that big extreme loss of power

mine was always like a clock at 6800-7000 and losing 40-50whp
then I started to have another other dip in power at around 4500rpm

Im only NA power with the 7AT ,

Ive seen a few other guys having a cracked flywheel .

I have a 7at, did you start to build up hp towards redline? mine dips then starts to build up right before redline.

look at it ,,,
2 line shown when I had the problem and fully tuned the best we could
and the better one is after I got the car back from the dealership (flywheel and tranny replacement)
Nissan 370Z Forum - Megan370z's Album: Dyno Day 28 Nov 2011 (Dynojet vs Dynapack 3000) - Picture

Looks somewhat similar but mines way more dramatic, BUt I don't suffer any loss till 7100 rpm, i actually gained 40 whp throughout the power band and about 30 peak tq and 40 midrange.

remember you are FI and im only NA ! so yeah the number seem more dramatic on yours but its about the same.

remember that dyno sheet show the last time I was fully tuned with the cracked flywheel that has been cracked for almost a year...
It didnt show much of any problem in the mid range at the beginning ,, only at 6800+

Hmm Ill keep an eye on it, hopefully thats not the case..

I hope so too. That's gonna be a fat repair bill

Ya.......... Funny thing is if that happened then Ill be wondering if it was from day to day driving or my SC... loL!

isnt 7100 about the time the factory rev limiter kicks in? that could be a clue to your problem.

I think it's 7500? 7600? Mines set to 7700 I believe