4T60 Problem?

[robmaxfli]

Hi - first timer here.

1991 Buick Riviera with 120K miles
Problem: With the engine cold and driving off in the mornings, the car simply won't accelerate worth a darn when I give it gas. It doesn't stumble or jerk or rev high (miss a gear or slip), it will just barely go. It also makes a distinctive whine noise while the issue is happening.
Once the car reaches full operating temperature the car accelerates and cruises just fine. No check engine light, trans filter/fluid changed 20k miles ago, fuel filter changed - spark plugs look good. Trans fluid color looks good and is full.
I am thinking that this a transmission issue vs. an engine issue...but of course I am no pro. Just looking for some advice

thanks Rob

[bob442]

Wow this could be a whole lot of things, does the whine noise happen when idle or in park? Do you have first gear when you have these issues? It could be in limp mode, I had a exact problem with a friends car, it lost its power to the trans because a pin was bent down at the connector to the trans. You will need a mirror to see this, and if it is bent, you need to be extremely, And I mean extremely carefully when bending the pin back if it's the issue, cause if you break that pin your SOL



Sent from my iPhone using my iPhone at work cuz I have nothing to do

[robmaxfli]

Wow this could be a whole lot of things, does the whine noise happen when idle or in park? Do you have first gear when you have these issues? It could be in limp mode, I had a exact problem with a friends car, it lost its power to the trans because a pin was bent down at the connector to the trans. You will need a mirror to see this, and if it is bent, you need to be extremely, And I mean extremely carefully when bending the pin back if it's the issue, cause if you break that pin your SOL



Sent from my iPhone using my iPhone at work cuz I have nothing to do

Yes- whine happens in at idle and in Park...Are you asking me if I can shift all the way down to first gear? not real sure about that question
Do you know where that connector is located?

thanks!

[bob442]

Simply do you have first gear, as in does it start in first gear when you shift into drive and you have this problem. If you or someone hasn't touched or messed with the trans lately the the issue I discribed most likely isn't the problem. Does this problem go away when the trans is warm?



Sent from my iPhone using my iPhone at work cuz I have nothing to do

[robmaxfli]

Yes it will go in first gear but it won't move quickly at all. Problem does go away when its warmed up.

[bob442]

how do you know the "trans" is in first gear, lets clear this up and go onto the next step i dont think you should be able to go over 40kph in first

[robmaxfli]

Yes- pretty sure it is in first gear when I start off...It revs a good bit and then "slowly" changes gears to second..

[bob442]

it could be having 2nd gear starts or 3rd

[robmaxfli]

any other suggestions?

[bob442]

RPM vs Speed to confirm its in first gear thats all i can shoot at ya

[TGP37]

Yes it will go in first gear but it won't move quickly at all. Problem does go away when its warmed up.

Is it possible you are having trans fluid problems? Did you check/fill the trans fluid when running and well warmed up? If you check and fill the ATF when cold and the car is off, you will not get the right amount. Having the right amount, not too much or too little, is important with automatics.

Also check and make sure the ATF isn't brown and/or smells burnt.

What about the belt? That sometimes will squeak in goofy ways when cool and damp.

EDIT: "Yes- pretty sure it is in first gear when I start off...It revs a good bit and then "slowly" changes gears to second.."

Slow shifts could happen when fluid is getting low. The ATF will start to foam/bubble and that allows air into the fluid. Air compresses and ATF does not. The piston travel time is relevant to shift speed. If the ATF must first compress the air then the piston, the shifts are going to be slow.

Best you could do is properly check the ATF level by driving the car around for 15 minutes. Park and keep idling, now check ATF fluid. I bet it is low.



Do you have ATF in your coolant? Sometimes the line breaks in the radiator and you could loose a lot of needed pressure....until it warms up some.....just a guess.