Extreme loss of power at 7100 rpm. Help needed!

kosstick · 01-28-2012, 10:01 PM

Quote:

Originally Posted by Zat_Zuma

Is your transmission or torque convertor shot?
I assume you have a automatic transmission.

+ or - 0.5 volts on your MAF air flow is a huge difference. Expecially with the 3" intake piping. Plus if your boost is low, I would automatically be looking for a boost/vacumn leak in your couplings/connections or the boost relief valve could be sticking.

I doubt my trannys shot it shifts fine and no matter what hp or gear pull its always 7100 rpm. No matter if it's 350 who or 410 or 390 or 450

Anyway I'm confident in gtm uprev and my tuner. Im just hoping I can make this problem go away quicker

Mkai0 · 01-29-2012, 07:08 AM

I'd have to agree with with what Zat Zuma is saying about checking for boost leaks. I've already had to retighten some of my couplers on my GTM Stage 1 kit. What kind of AFR's #'s are you getting?

awkwardturtle · 01-29-2012, 07:21 AM

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.

kosstick · 01-30-2012, 09:28 AM

Quote:

Originally Posted by awkwardturtle

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.

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.

Nixlimited · 01-30-2012, 10:47 AM

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.

Megan370z · 01-30-2012, 11:02 AM

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 .

kosstick · 01-30-2012, 11:15 AM

Quote:

Originally Posted by Megan370z

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.

Megan370z · 01-30-2012, 11:18 AM

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

kosstick · 01-30-2012, 11:32 AM

Quote:

Originally Posted by Megan370z

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.

Megan370z · 01-30-2012, 11:40 AM

Quote:

Originally Posted by kosstick

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+

kosstick · 01-30-2012, 11:44 AM

Quote:

Originally Posted by Megan370z

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..

weiboy718 · 01-30-2012, 12:56 PM

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

kosstick · 01-30-2012, 03:52 PM

Quote:

Originally Posted by weiboy718

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!

Dark Sarcasm · 01-30-2012, 06:59 PM

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

kosstick · 01-30-2012, 07:08 PM

Quote:

Originally Posted by Dark Sarcasm

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

01-29-2012, 07:08 AM	#2 (permalink)
Mkai0 Base Member Join Date: Dec 2010 Location: Somewhere in Texas Posts: 209 Drives: 2008 G35 Sedan Rep Power: 16	I'd have to agree with with what Zat Zuma is saying about checking for boost leaks. I've already had to retighten some of my couplers on my GTM Stage 1 kit. What kind of AFR's #'s are you getting? __________________ Eibach, Tanabe, Blitz, Vertini, GTM stage 1.5 SC, Aquamist, Invidia, Alto built 5AT, Edge Racing, Racelogic, GTM driveshaft, 440 whp in 101F TX heat..

01-30-2012, 10:47 AM	#5 (permalink)
Nixlimited A True Z Fanatic Join Date: Aug 2009 Location: San Diego Posts: 1,235 Drives: 15 GT-R / 11 Prius Rep Power: 27	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. __________________ Car Sold! Pleasure being a part of the Z community. New ride: 2015 GT-R - 647 WHP / 641 WTQ (e85) & 543 WHP / 519 WTQ (91)

01-30-2012, 11:02 AM	#6 (permalink)
Megan370z A True Z Fanatic Join Date: Oct 2009 Location: Canada Posts: 1,156 Drives: 370z Rep Power: 25	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 . __________________ Megan Journal Click Me ....................One Man Team Motorsport Click Me

01-30-2012, 11:18 AM	#8 (permalink)
Megan370z A True Z Fanatic Join Date: Oct 2009 Location: Canada Posts: 1,156 Drives: 370z Rep Power: 25	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 __________________ Megan Journal Click Me ....................One Man Team Motorsport Click Me

01-30-2012, 06:59 PM	#14 (permalink)
Dark Sarcasm Track Member Join Date: Dec 2010 Location: Katy Texas Posts: 552 Drives: 11 CTS-V Coupe Rep Power: 17	isnt 7100 about the time the factory rev limiter kicks in? that could be a clue to your problem. __________________ wax

01-29-2012, 07:21 AM	#3 (permalink)
awkwardturtle Base Member Join Date: Nov 2011 Location: minnesota Posts: 98 Drives: 07 Civic SI Rep Power: 15	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.

01-30-2012, 12:56 PM	#12 (permalink)
weiboy718 Track Member Join Date: May 2010 Location: Bay Area Posts: 923 Drives: Infiniti G37 Rep Power: 17	I hope so too. That's gonna be a fat repair bill

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