JonGS3

I've spent a lot of time searching and have read the various posts about the little hiccups our transmission can have. I don't have any warning lights or a CEL on for shift solenoids so I think everything is healthy otherwise.

I've had my car for a little over a year now. I bought it right before last winter (did a trans fluid drain and refill right after getting it) and noticed these issues when it got cold out. They went away during the summer when it warmed up and now have come back again. The car is fully warmed up when it does this so it's not a matter of it shifting differently when the car is cold; just when it's cold outside (like 45 and below)

If I'm accelerating up to anywhere between about 40 and 55mph, it will hold 4th gear for maybe about 30 seconds before shifting into 5th regardless of whether or not I keep accelerating or back off the gas and it happens more frequently when driving downhill. When it's warmer out it will shift into 5th normally without holding 4th. It doesn't make a difference if it's in normal or ETC mode. Sometimes when it's holding 4th, I can put it into snow mode and it will shift into 5th right away. It doesn't do this, regardless of outside temps, when getting onto the highway where I'm getting up to 65mph+.

It also seems to hesitate when shifting from 2nd to 3rd. It's like the RPMs will hang up right after 2k while the trans thinks about what it has to do and then shifts. It mostly does this in slow traffic or driving through neighborhoods, especially when accelerating from a stop sign if I don't completely stop and let it downshift into 1st. Sometimes it does the same when downshifting into 2nd.

Occasionally if I'm braking downhill to almost come to a stop, like if I'm slowing down while driving down a parking garage ramp, the downshift into 1st is a bit abrupt and jerky.

It drives perfect if I get on it hard in which case it runs through all of the gears just fine. I do plan on changing the trans and motor mounts as there is a faint jerkiness when getting on and off the gas sometimes regardless of the weather. I've had enough old cars to be able to feel when the motor mounts start to wear. My one thought is that maybe the rubber in the trans mount is contracting enough when it's cold that the trans is moving a little when it shifts and maybe that's the cause for the 2-3 sluggishness.

I've reset the trans ECU before to erase the learning mode history and sometimes that makes these issues go away briefly but they still come back within a drive or two. I'm doing another drain and refill of the trans fluid this weekend but I can't really think of what would cause this otherwise.

Aroble34

Hi I have an 02 gs300 Sport Design I have been looking everywhere to diagnose this exact problem you have brought up. I am starting to think it is normal for the car.

I have tried...
Trans Fluid change
Gaskets replaced
ECU reset

With improvement to the car, but no full fix...

Have you had any luck figuring out a fix?

sbagdon

Sounds like that whatever it is, it's outside the trans body. Besides the trans ECU, what other parts contribute to shift behavior... relays, sensors, controls, etc?

JonGS3

I changed the transmission mount and did another drain and refill. The old mount was definitely shot. After getting it out, I had to jack up the trans probably about a good inch to get the new one in. That pretty much cured everything described in this below paragraph. I don't think changing the fluid again made any real difference. The stuff that came out was nice and red...not much darker than the new fluid.

It also seems to hesitate when shifting from 2nd to 3rd. It's like the RPMs will hang up right after 2k while the trans thinks about what it has to do and then shifts. It mostly does this in slow traffic or driving through neighborhoods, especially when accelerating from a stop sign if I don't completely stop and let it downshift into 1st. Sometimes it does the same when downshifting into 2nd.


Now that it's warm out again it pretty much completely stopped the delay shifting into 5th gear. I feel crazy attributing that to ambient temps but it's the only variable I've noticed that consistently causes it.

TrueGS300

The only thing that makes sense to me would be an ambient air temp or Intake air temp sensor reading that is giving the ecu/tcm a reason to perform a certain way. More likely the intake air temp (IAT) sensor which in turn would effect certain engine performance variables. My thoughts are that with how important throttle function is to both the engine and transmission, you may be suffering from a filthy throttle. Don't ask me the science behind it, but consider if the outside temp is what seems to be determining the cars behavior, and the air coming into the engine is being both metered and temperature monitored, then air passing through a throttle that should be opened a given amount, but isn't flowing quite good enough do to carbon build up may be effecting it slightly. Same goes for if the MAF (with integrated IAT) is dirty. I think you should clean both your MAF which contains the intake air temp sensor and throttle body and see if this helps.

Tank

iTrader: (19)

Trans shift will hang in cold weather because trains fluid hasn't reached normal operating temp. Normal.