No overdrive/4th gear?

[dikk]

Hello

Tried a search but with no luck, and i don't know if the subject is correct but my problem is as follows.

 

Lately my car has failed to jump into that "last gear" or whatever it is, that usually occurs above 70kmh (45mph maybe?). So when i drive in OD at speeds around 70kmh, the car is doing approximately 2000 rpms instead of the usual ~1500. Sometimes it goes into the "last gear" and the rpms drop after driving 20-30 minutes but it almost never occurs when the car is cold, as it used to do.

 

Does anyone have an idea about what's going on? Is my transmission going to hell, or is this usually something that can be fixed without having to risk bankruptcy? I hope i explained it right so that you understand my problem... Any help or suggestions are appreciated.

[FastSE2DR]

my car does this too...i was told to check grounds(never have lol) and have it flushed(nope havent yet)....but assuming yours is the regular 4T60(or is it in 90?) its prolly not a ground. I would give a flush a chance or atleast look at your fluid etc...

[dikk]

I don't know what transmission it has, but it is a 1990 3.1L so maybe someone else can tell us that.

I'm glad that you answered, and you should know how irritating this is...but check grounds, do you know where? And have it flushed, do you mean change the transmission fluid? :oops:

[FastSE2DR]

yup change the tranny fluid...also this was just brought up in another thread about the car not going into closed loop(o2 sensor being bad) and the tranny not locking the TCC up...but again im not sure it applies to your vacuum controlled tranny...

[3pt1lumina]

okay... here's what happens with my 90 3.1 Lumina with the 4T60 (4spd w/ o/d)

 

If it's cold out and the transmission is cold, the car will shift at 15, 25, NOT at 35 but then at 47mph. Once the car gets warmed up to operating temperature, it will shift at 35.

 

If it's warm out, it will shift at 15, 25, 35, 47 but at about 55-60 it's constantly up and downshifting... from 60+ its fine. BTW this is all on gentle acceleration.

 

I did do a transmission flush and put in MaxLife Valvoline Fluid with this stuff called "Lubeguard" (was recommended by a transmission shop)... car shifts 10x better when warm, but when it's cold its only so so...

 

If I had to guess, our transmissions are probably tired and are going to need to be rebuilt soon. I take it easy on mine and drive the car relatively gentle unless provoked by a Honda or something. Mine has 132k, never been touched so yeah...

 

youre not alone

[dikk]

Ok....

Vacuum controlled...I have noticed that some of the hoses from the TB have started to wear because of heat, is there any chance that this could have something to do with my problem?

[dikk]

3pt1Lumina>

It sounds like your car acts the exact same way as mine. But it also has trouble to stay in the highest gear, once it has kicked in.

Thanks for the tips on the fluid, i will look into that.

[TeeJay3800]

If it's cold out and the transmission is cold, the car will shift at 15, 25, NOT at 35 but then at 47mph. Once the car gets warmed up to operating temperature, it will shift at 35.

 

If it's warm out, it will shift at 15, 25, 35, 47 but at about 55-60 it's constantly up and downshifting... from 60+ its fine. BTW this is all on gentle acceleration.

What you're describing is the TCC not locking up on a cold engine. The converter clutch will not lock-up until the coolant temp is at 150°F. If my car is cold and I drive at 45 in "D" it will be in 3rd without lock-up RIGHT until my DIS says the coolant reaches 150; then I feel and hear the TCC engage.

[3pt1lumina]

On the 4T60E in my dad's 97, it shifts 10, 25, 35, 45 no matter what the operating temperature is? why is this??

[TeeJay3800]

It will shift four times all the way up to 4th gear no matter what the temp is.

 

I was saying the TCC won't engage until 150.

[1990lumina]

I was saying the TCC won't engage until 150.

 

Same thing with mine...it's normal operation.

 

Just for reference, the vacuum controlled tranny is the "4T60", and the electronically controlled tranny is the "4T60-E"

 

However you would have the 4T60

 

Anyway, when my car is cold it doesn't lock the TCC either, normal operation.

 

If it mechanically isn't shifting into Overdrive, then someelse is wrong...try and filter and fluid change first and see what ahppens.

[3pt1lumina]

sweet! I always thought something major was wrong with that. Now if it didn't slip on the 1/2 shift when I floor it from roll (my 90 that is)

[ns87]

I posted that somewhere else too. WHAT IS THAT 1-2 SLIP???!?!? My Supreme does that

[Nick1234]

if the torque converter is not locking up it could also be your brake switch. It could get out of place. Try driving down the road when the car is warm above 45 and put your foot behind the brake and pull it towards you, and if that doesn't work still get down there and make sure it is in the proper place.

 

 

Nick

[pwmin]

there was overlap from 91-92 for the vacuum controlled and the electronically controlled 4T60(E), so its obviously a 60 for various reasons (90 and vac.).

 

dont flush your tranny, especially if something's already wrong or if its got 100K. you might get lucky and fix it with change if something's wrong. if the bands or cluthes are going, flushing it will completely ruin them.

[Grand Moff Joseph]

okay... here's what happens with my 90 3.1 Lumina with the 4T60 (4spd w/ o/d)

 

If it's cold out and the transmission is cold, the car will shift at 15, 25, NOT at 35 but then at 47mph. Once the car gets warmed up to operating temperature, it will shift at 35.

 

If it's warm out, it will shift at 15, 25, 35, 47 but at about 55-60 it's constantly up and downshifting... from 60+ its fine. BTW this is all on gentle acceleration.

 

I did do a transmission flush and put in MaxLife Valvoline Fluid with this stuff called "Lubeguard" (was recommended by a transmission shop)... car shifts 10x better when warm, but when it's cold its only so so...

 

If I had to guess, our transmissions are probably tired and are going to need to be rebuilt soon. I take it easy on mine and drive the car relatively gentle unless provoked by a Honda or something. Mine has 132k, never been touched so yeah...

 

youre not alone

 

Wow, you just described my Lumina's tranny perfectly! It has had that exact same pattern forever, and I always assumed it was just a crappy tranny that was on its way out!