"normal" transmission slip?!?

[VQboy]

Is there such a thing as normal transmission slip?

Background: 1999 I30. No previous transmission/engine work or mods (except factory recommended maintenance). 80k km on odo.

Condition: the apparent "transmission slip" seems to occur only when engine is not fully warmed up. Would occur when the transmission shifts from 2nd to 1st gear. An example would be slowing down to about 20km/h in 2nd gear, then stepping on the accelerator enough to cause an apparent gear change to 1st. While performing this sequence, the rpm gauge would read an increase to about 2500rpm as the accelerator pedal is being depressed in 2nd gear, jump to 3000rpm (apparent gear change to 1st?), then settle back to 2500rpm. When the engine is warmed up, this "transmission slip" does not seem to be reproducible. The car shifts "normally" otherwise.

Questions: Is this a transmission slip? If so, is it "normal"? Is it something that needs to be corrected soon? Any and all input is greatly appreciated! =) Thanks!

VQBoy

[Q45tech]

The AT has a thermistor to measure the ATF temperature to compensate for changes in viscosity vs. temperature. The modifies the ATF pressure at some clutches.

Assumming the transmission has been flushed and fluid exchanged frequently and the ATF meets Nissamatic D specifications.

Just like the engine not a good idea to crank and drive away until warm as you place undue stress on warming up from cold components........especially flooring things cold [wait 10 minutes after cranking].

[Jeff Williams]

I had the similar thing with my 1995 Maxima. It seemed to slip, between 2-1 shifts, if I was barely moving, or if I was slowing down for a red light, and it turned green, while I was creeeping to the light. The dealership said the same thing Dennis said. It is normal slippage. Try not to put yourself in that position again.

Also, when cold, the car wouldn't shift into overdrive.

[szh]

Hi, Dennis.

Just like the engine not a good idea to crank and drive away until warm as you place undue stress on warming up from cold components........especially flooring things cold [wait 10 minutes after cranking].

Out of curiosity, how long do you and others wait after starting the engine before you "drive away"? Not flooring, of course, but just to start driving relatively gently down the road!

Z

[PalmerWMD]

VQ boy:

You did not list your location or temps involved but from your description of milage in km i surmise you are in Canada and are exeriencing cold mornings?

At your milage (50K miles) and maintenance histroy transmission failures ( and that includes slippage) are almost unheard of.

It is possible to expereince weird TCU/ECU actions on cold mornings ( like Dennis said), that may appear to act funny but arent slippage in the stricter sense.

Strictly from your description ,I surmise, you simply have slow shifting on cold mornings.

Real slippage (which also begins show up first on cold mornings) , tends to show much more severe symptoms, most notably when you try to take off ,your throttle input will be translated into rpm before discernable thrust occurs and no real correlation seems to exist for a moment ( not just during the time the transmission shifts) with your rpm and speed.

I have also experienced temprary (real) slippage in another vehicle with a healthy transmission on extremely cold mornings.This was caused by the ATF "shrinking" under temp and causing a temprary underfill condition on very cold mornings ( MN winter).

With dealer advice I cured this by adding some ATF (this may not be applicable in youre case just mentioned it for completness).

Fred..

[Q451990]

Out of curiosity, how long do you and others wait after starting the engine before you "drive away"?

Unless I'm in a huge hurry, I try to let it warm up to at least the temp. gauge coming up a little in the normal range. I keep the transmission locked into "3" until it's up to 3 o'clock (full warm).

Heath

[VQboy]

Fred,

Yes, I do live in Canada, and recently the temperatures have been close to 0 degrees Celsius. This transmission slippage seems to only occur when I first drive off before full engine warm up (e.g., as I'm driving down the street from my house and rounding a corner about 20km/h, then accelerating gently, but enough to cause a down shift to 1st). Once the engine hits normal operating temperatures, it's difficult to duplicate this situation.

I'd like to THANK EVERYONE who replied to my posting. You've all given me greater insight into my car, and put my mind at ease! This forum has the most awesome members! =)

VQBoy

[nuQ]

VQBOY, i had the EXACT same problem with my Q last winter! always happened the same way. when pulling out of my driveway on a cold day without a warm up (in reverse), then putting in drive, and going about 20 mph until hitting a stop sign, then hitting the gas again, a very noticible slip could be felt (rpm's increasing then the drivetrain engaging). after spending time and searches on NICO, discovered that a complete trans flush in manditory, and also a warm-up of the engine (at least 5 minutes---which i always do now). have NEVER experienced the slip again.hope this helps. jeff