Initially I was thinking the same thing. But after the thread I just linked I m not so sure anymore cuz ecm reflash helped only couple weeks.

But it since it helped couple weeks, I do think it is something with ecm causing it.

However it is way out of warranty, an inspection cost 150 and may not detect anything.

 

Do you feel any mechanical action when the rpms bounce up and down? If not, it could be just a computer/ecu related problem.

 

No mechanical action, i do not feel jerk and surge, just plainly Engine speed goes down as i am shutting it off for a quick sec

 

And does this happen in manual mode too or just Drive?

 

it it is in both modes

 

My 2012 does this here and there, no consistency but it's generally around that speed and letting off the gas fully. Bogs down a bit until it coasts down a little slower or I give it a quick blip of the throttle then it settles in nicely. Confused transmissions. Maybe a Canadian thing?

 

Well, if you cleaned your maf and throttle bodies and it is still doing that, it could be a pvc/vacuum related problem. If those issues aren't it, there may be a problem with the torque converter. It's the torque converter's job to match the speed difference and keep the rpms constant. Since you said this happens with your foot off the gas there is no load going to the wheels so they're spinning freely when this problem occurs. That means your driveshaft is moving faster than your engine flywheel.

 

It could be fuel related, such as a pump or filter. Or something getting stuck. I would check fuel pressure just to make sure. Also get your tranny and fluid checked. I wouldnt worry about it too much unless it compromised drivability/safety. Just keep an eye out in case it gets worse.

 

maybe, it bugs me to see it doing and hear the exhaust sounding it is shutting fown

 

Yea Rs maybe I will just keep driving it until some problems come up. The only thing I can think of is the fuel damper as occasionally I do hear the noise caused by it described by other people.

 

Might want to also check the 370 z forums. Same engine so someone there might have experienced and fixed he same thing.

 

did you ever figure out what this was? My car does the same exact thing.

 

It's a dirty MAF or throttle body...I'd clean the throttle body and just replace the MAF instead of screwing around with that

 

Have you fixed the issue?
TB cleaned. MAF cleaned. Nothing shows on scanner.

 

I have the same exact problem in my VQ37 Q50 and I posted a thread on the Q50 forum about this that is nearly 55 replies long with almost 4 times more words, description and discussion than your thread here has. My video that I use to demonstrate what you and I are experiencing is also long, high definition, steadily filmed and accompanied by timestamp descriptions of the dips occurring in the footage.

I need you to reply to me and tell me if you ever sprung further investigation into this issue or ever found a solution besides the temporary yet unsuccessful ECU reflashing at the dealership. I have attempted every suggestion on this forum with the exception of one or two things; and ruled out even more suggestions that were made on my Q50 forum thread.

Please, I ask that you give my thread a read and get back to me with perhaps some useful information.

https://www.infinitiq50.org/threads/.../#post-1456586