Well, this is kinda difficult to explain but I'll try my best.

For a long time I've had the feeling that something is wrong with my 2004 Z.
Sometimes it just plain out lacks in performance! And it doesnt have anything to do with humidity or temp. since it can vary greatly within the same day without any weather changes.

It's really getting on my nerves since I dont have a clue on what it can be?
Sometimes when i get on the gas, it accelerates very good, other times it's just like pulling a weak rubberband and the car feels like it lost 80 HP or something..!
I really have no idea what it can be, but I would like to have it figured out soon since my warranty is about to expire!
The car is totally stock with about 20K miles on it. When I bought the car it had 10K on it and it didnt act like this at all.. I have been on it pretty hard, pushing it through out the gears pretty often!

Does anyone have any suggestion on what can be wrong with my baby?
cracked piston/ring?
clutch?
electronics error?

Let me know what you think guys.
Thank you.

 

man i think its bc u got used to the speed...thats what happens. The speed feels normal to you bc u drive it everyday...I would suggest bringing it to nissan and get a tune up....Hope that helps somewhat

 

I agree with the getting used to the speed factor.


try a simple ECU reset and see if that helps.

Any oil consumption? could be a power loss from the pistons then....

 

^^^thats what i was gonna recommend. go to the dealer and let them do the hesitation TSB on it. they pretty much reload the ecu program. it helps alot of the 3.5 altima guys out

 

its not bc I got used to the speed, Im very awear of that factor since I always fall victim to that when I get a new car.
But the power lack can occure within the same day!
So this TSB, what is that? Is it basicly a reflash of the ECU?
Im from Denmark, so I'll have to know what it is so I can explain to the dealer what it is I want him to do. This might seem odd to you guys, but there is less than 35 Z's in the whole country here so the dealers doesnt really know anything about the car, sad to say

 

This could also be due to which fuel timing map you're on. There are 3 timing maps: one for normal driving, one more aggressive, and the last one the most aggressive. If you've been driving slowly for a while and then punch it suddenly, the pull won't be as strong. But after you've been driving leadfooted for a bit, the timing map will switch to the aggressive one and the pull will be stronger.

 

You know your car so I am not going to debate your summary. Time for a diagnostic test including compression check.

 

go to a track. your trap speed will tell us all whats wrong.

 

Are you turning off VDC/TRAC before you punch it all of a sudden (assuming you don't have a Base model Z)?

 

+1

 

It actually works the other way around mostly.. It usually happens when I've been on it pretty hard through out the gears.

It's a problem that comes and goes, so I'm affraid it wont show anything through a diagnostic test? It hasn't showed any sign of error codes.

Well, actually something has been wrong before! When I was drifting it around, beaten it pretty bad, then all of the sudden I couldn't turn the ESP back on! And the windows wouldn't work eighter!? The ESP sign which usually flashes on and off when you pound on it, was on all the time.. Even though I deactivated it before I started. This ESP thing actually happend 2 or 3 times more, when I just drifting through a curve and then spun all the way around.
Everytime this ESP thing happened, I had to turn the ignition key all the way to off position and back on before everything returned to normal. Strange?

 

It seems in Europe the VDC is called ESP.
What you are describing (light staying on) is normal.
There are many posts about that:
Basically the ESP is never totally off when you use the factory switch. If you drift it so hard (e.g. spin it) the electronics get confused by the extreme readings of the yaw sensor and go into a mode where slip light and vdc/esp light is constant on meaning that the system now really does not use the stability program any longer until you turn off the car and restart.
After you have reached the constant on SLIP light condition, you can really have fun with the car even when braking into a turn, no more interference, only ABS should be left working.
There are also many people that hardwired a switch into the power connection to the yaw sensor, to deliberately create this "mode" without having to spin the car before it goes into this mode.

 

Good to know pedroosan, thanks.

 

I've had it on the dyno and it does lack a little performance, but obviously not as much as I thought.. I'm not sure if it's because it doesn't act like on the road or what's going on, but I think it performs very weak on the street.
The dyno shows crank hp and torque, since thats the only way we dyno cars here in Denmark. The temp. and humidity has been corrected so it shouldn't be a factor.

 

I finally figured out what was going on!
It seems I have a bad Ignition coil (spark coil?). periodically cylinder No. 2 will misfire resulting in the car only running on 5 cylinders. It comes and goes. Yesterday the MI indicator came on and hte error code showed a bad ignition coil. A new one is on the way so everything is good!

 

nice congrats man! OH and when u do a donut or something. Anytime your break fluid gets tossed around in that holder, ur esp light will stay on bc it thinks it needs break fluid...happend to me plenty of times...Sometimes my break light even goes on for a few mins...

 

Problems with no associated check engine light are always a pain in the *** to diagnose. Lucky for you the light came on, glad you got your problem resolved.

 

How about this one: Is it normal if I gun it in 1st from a slow 5mph roll and it feels like accelerating in 2nd/3rd? TCS is off, and there's no wheelspin, chirp of the tires, but it sort of lunges forward once I get high up in the revs.

 

what do you want it to do in first at 5 MPH, spin violently? Mine doesnt really go crazy either if im cruising at 5 MPH then punch it but its spinning by them time i change into second.