Hey, during driving I have noticed recently that my Z isn't accelerating as fast or smooth as it should be, and it requires more effort on the pedal to make it accelerate. There are also spikes in acceleration, especially from idle. Its not a serious problem and the car is drivable at all speeds and rpms, but I feel like I am missing out on performance.

Anyone have any ideas as to what the issue could be? Ive noticed that after every oil change it accelerates smooth again (and less of a rough idle) but only for about 1k miles.

I have a 2005 touring automatic with 35k miles on it, no mods. I just switched this time to synthetic oil, but it was having this problem before this. Any ideas?

 

Does it feel like it's starving for air? Mine has recently started doing that as well. 05' auto 45K.

 

yeah it does somewhat, although I am not entirely sure of what staving for air would feel like. It kinda makes a vacuum noise when I go on the highway and try to accelerate. it is very slight and may not be the same issue but it is noticeable.

 

ticket, how long have you had the car? i notice this starts happening to me everytime the temps are over 95 degrees outside.. its like its revving and everything, but my butt dyno says its just not really going anywhere too fast anymore. I see yer in FL... really its very common to have this happen in the summer.. dunno exactly why down to the physics, but it is what it is.

clutch wasnt slipping, just felt lame. Spotty almost.

btw, this ECU back n forth fight was finally WON by doing a Cobb reflash... stock or not, id never own a VQ w out a flash tune again.

 

I got the car in April Used so its fairly new to me, but Ive driven enough that i can sense that it shouldnt be doing what it is, and it was still doign this in may(which is still warm here but not in the 90's), so I dont know if its a temp issue, especially when a minivan who isnt trying beats me out of a light.

The fact that it gets better with an oil change is what confuses me about it. The oil level seems fine. Is it maybe a filter issue? Ive also noticed that my coolant resivoir tank is completely empty, is this a cause for concern? Any ideas?

 

Could directly be related to heat soak, yes, this happens for me only if its really hot out and i've been driving it for some time. The power is back when the engine is still cool. I would fill that reservoir tank up man. Check under the radiator cap and see if u have visible coolant under it. Not when its hot of course.

 

ah ha! so i was partly/mostly right.. its a new car for you.
Welcome to the 350z... its really not that fast.

https://my350z.com/forum/intake-exha...ecu-reset.html

try this.. and use a stop watch, its extremely picky.. you cannot wing it close to 7 seconds etc...

if it suddenyl drives better, my reccomendation is to make sure all your fluids are correct of course.. and then get yourself an ECU flash tune.
Im serious.. im not a kid telling you to buy something shiny and cool, its just a known PITA thing about stock ECU'd VQ cars.
its fairly cheap and youll scratch your head and wonder why the car wasnt like that to begin with.

Its quite odd.. i started a million threads like this 2 years ago.. i hear ya man.

Believe me.. heat is the ENEMY w our cars on a stock ECU, period.

 

I think filling the overflow tank is a good idea so I will try that first.

I am a little bit confused though, why would resetting the computer affect the power issue? Also I didn't quite completely understand which operational procedure I am supposed to perform. Is performing an ecu reset easy or can troubles occur if not done properly?

 

sorry, you want to do them both.

Reason being is that our ECU learns over time.. it loves to kill performance too it seems.
ESPECIALLY when you start buying bolt on parts... they are almost fully pointless until one buys a tuned ECU flash to minimize this learning curve.. it fights back over the gains of mods...

alas your car is stock but you are experiencing a common Z issue, learning ECU makes the car less fun.. the best way to see if this is what you are experiencing is to learn and use the reset procedure every 90 days or so...

the fluids thing of course is fully separate, just make sure theyre good of course..

but the ECU thing.. its just a weird gremlin in our cars.. all of em have it, and youre not crazy for what your experiencing. its very common and very hard to explain to a mechanic.

 

So then you are saying that its most likely the ECU learning over time that is decreasing the power? How does that relate to the heat issue? And also, how does that explain the fact that the power increases when the oil is changed?

Is there any risks to resetting the ECU? will it decrease engine life at all or lead to computer malfunctions? Thanks for your help

 

my point is that its normal, can be thwarted by quarterly resets, and can be solved by reflashing the ECU, which leads to a very very fun car.

 

Ok i will fill up the coolant and reset the ecu.

So to clarify:

do i do the Accelerator Pedal Release Position Learning and then the Throttle Valve Closed Position Learning? is there a general ecu reset procedure?

And for example to do the Accelerator Pedal Release Position Learning:
1. i get in the car and while its in park, turn ignition ON and wait >2 seconds
2. turn it OFF and wait >10 seconds
3. Turn it on and wait > 2 seconds
4. Turn OFF and wait > 10 seconds and once i turn it on again it will reset the accelerator pedal release position?

I like being precise with this stuff mostly cause I am not exactly sure what I am doing. How do I know if it reset or not?
Once again thanks for your help

 

interesting

 

w out re reading it myself, it is succesful by the flashing of the lights that it states, i think its the cel light flashing etc.

Unless your cars throwing a code and REEEALY lagging, then youd have another problem.. just saying its a good diea to know this issue and to know how to reset the ecu. Just a part of ownership.. if it doesnt cure your slight issue, you shoul dahve it scanned for thrown codes after driving it a few weeks. Some can be stored w out showing a service engine light.