7at. Weird behaviour.
 

Hello, people. Good day.

When up shifting from 3rd to 4th in manual mode, shifts are too severe and fast... seems like it were a double clutch transmission with how fast it changes, yet everywhere else is shifts at normal speeds. It also sometiems makes a tiny clicking noise. And ocassionally will 'slip' when changing... or what I think others call "flare"... it will jump around 300 revs up before going down and setting on 4th (again... also bullet fast).

This also occurs only when the accelerator is at load... and knly at around 3-4k revs... If I drive barely touching the pedal or if I up shift higher than 4500, it shifts normally.

The car was also scanned just 3 months ago for an unrelated issue; nothing came up.

Weird part is that... it only has 30k miles.

So if that gear is starting to slip... at 30k? And if it needs transmission fluid change or... umm... flush... at 30k ?

Those abrupt shifts dont really clunk... sometimes in general... and on other gears... but I think that happens nornally at times given these transmissions can a few times be a bit dim-witted... its just a tiny click.

There are also sometimes HUGE delays in manual mode when downshifting going really slow... from 2nd to 1st...
But thats always happened... mentioning it just in case.

Other than that... it's always up and down shifted normally and without issues... responsive...normal quick...no noises... and it still does... save for 3-4


Thoughts?

Thanks for reading.

Forgot to mention... the car has this common issue where when at normal operating temperature (oil at 200-220), it loses noticeable power... perhaps around 10-15%. Mentioning also in case it points to something.

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From what folks have posted before it is time for a drain and fill. Even though they say fluid needs no service people have better results changing every 30k.

3-4 shift is known to have a harsh double feel. My '10 does the same even after a fresh change and with a trans cooler. There is an update to the TSM which helps, see if you have it. Tunes which manipulate the torque demand will also help, did with mine which has 93k on the clock. I also note similar behavior jumping rpm between shifts mostly when cold as torque converter lock up only begins at 2475-2775 RPM and only between fluid temps of 122*-176*.

REALLY wish ECutek would get off their butts and install the OE available trans fluid temp PID into their friggin' app and desktop program already for reference while driving. :mad:

Thanks, Spooler.

Though... as for choosing between drain and fill *and* flushing... you'd opt for the former then? As a discussed-to-death topic, many are against flushing... and many are for it. Kinda hard to make a proper decision with so much contradictory information out there.

I appreciate your time.



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That sounds about right. I still haven't got around to performing any sort of tune given that I'm still unser warranty period... and yeah, I've experienced the 3-4 erratics and harsh feel previously, it just happened to be more evident these past few days. Mine is an 18. I'd hope any update to the software would already be there... but I'll ask at the dealership tomorrow.

Im "glad" to hear it is a somewhat common issue... so at least I'm not crazy and I won't be the guinea pig. but its quite terrible that it is a thing. I do like the 7at... and love the z in general... but it has some head scratchers.

A tune is definitely a need, specially with torque as you mention; as is with throttle response... it is very slow off the gate as is..

Thanks, Tractionless, for the bother of having read.

Good races.

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First thing that I’d do is check the fluid level & confirm it’s full; but not overfilled.
On my older 11’ base/touring...it was nearly 1qt. low with about 10k miles on it.
Don’t be afraid to perform drain/fills at your mileage, as it is a hydraulic system & will only improve vs damage.
Also, should still be under warranty...most are 5/60 in the States, unless you bought extended coverage.

I have decided to go through with a drain and fill... unfortunately it isn't covered by warranty... figures. But I appreciate your input; to be honest, i was a little wary of it, but with you guys recommending, decided to go about it.

Thank you, jchammond.

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Yup, a drain and fill on the transmission is a service item and that is not covered under warranty.

No bother. Let us know how the update goes if the dealer loads it.

Additionally, after it's off warranty you may want to consider a VR AT swap as it seems to have better behavior. Hopefully we'll get confirmation soon it will fit in the Z unibody.

http://www.the370z.com/engine-drivet...sion-swap.html

In case anyone find this post looking for answers should they experience the same issues, the transmission oil change solved things. Was well worth it... but I was suggested I be checking it every 15K just in case.

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Curious as to where the 1 qt. went if you didn't have a leak? :eek:

I'm on my 2nd transmission with this car and had the same issue.

Strangely it's HIGHLY temp related.

So lets say I drive the car 4-8 minutes and it's warmed up; Go into store, come back out maybe 20 mins later.

The 3-4 up shift, about 20-40% of the time, will do this strange thing where the RPMS jump up, then it locks into 4th gear.

It's been doing this for the past 20-30k miles, only during the summer, and only after the car sits for a little while after being warmed up, and ONLY at partial 1/3rd -2/3rds throttle acceleration. If I have the hammer down completely, then it's fine, but still a bit harsher than I'd like.

Transmission was changed at 54k miles, I'm now at 82k miles, have not touched it at all.

Taking it to dealer for fluid change, GOD HELP ME they do not F it up!

:driving:

I will never ever ever buy a hydraulic based auto from Nissan after this experience. I'm down for the 400z with the 6 speed next round!

Funny there's a thread on the g37 forums about the same issue.

My worry is that by having such a harsh shift from 3-4, doesn't that cause potential damage to the flex plate?

Why does it only occur on a 3-4 upshift?

To me this has to be not just fluid related, but software related (TSM?) as well.

I sometimes have the harsh up shifts in 4th or 5th. I thought it was the line pressure being changed from the Uprev tune, or transmission being cold since I have a cooler on it. I just had Nissan do a fluid flush, and so far everything seems to be working a little better. I'm right at about 20k. So, I would recommend services at around 20k miles.

What do you consider warmed up? I ask as I recently installed a 7AT temp. gauge and you aren't even in the range for checking fluid level at 8 minutes of driving.