Trans. up & down shifting abruptly...

[gonzo50]

On the highway this weekend, I'm driving at a constant speed of 75-80 mph.
I go to the left lane to pass traffic and reach speeds of 100-110 mph, safely.

During this manuever, if I let off the gas pedal slightly, the car goes into OD immediately, if I give it gas slightly, the car down shifts immediately, it does not find that sweet spot to stay in. :mad:

It just jumps back and forth suddenly and jerky from OD to 3rd, so I either have to stay on the gas pedal the whole time or just coast to a speed below 100-110 mph......what gives ??? :confused:

It's done this before, but I don't drive 100-110 mph constantly, or always. Thanks.

[Meteorite]

On the highway this weekend, I'm driving at a constant speed of 75-80 mph.
I go to the left lane to pass traffic and reach speeds of 100-110 mph, safely.

During this manuever, if I let off the gas pedal slightly, the car goes into OD immediately, if I give it gas slightly, the car down shifts immediately, it does not find that sweet spot to stay in. :mad:

It just jumps back and forth suddenly and jerky from OD to 3rd, so I either have to stay on the gas pedal the whole time or just coast to a speed below 100-110 mph......what gives ??? :confused:

It's done this before, but I don't drive 100-110 mph constantly, or always. Thanks.

Are you sure it is a 4-3 downshift, and not a converter unlock event? How much does the engine RPM change when this occurs? What axle ratio is in your car?

[gonzo50]

Are you sure it is a 4-3 downshift, and not a converter unlock event? How much does the engine RPM change when this occurs? What axle ratio is in your car?

I'm not sure, it might be the converter locking & unlocking, it's close to a 600-800 rpm difference. I'm running 4.10s in the rear, it's in my SIG.. It shouldn't be doing that at those speeds. :confused: Anyone else.

I thought that the converter locks at a certain speed and not suppose to unlock til it gets below a certain speed, ie:45-55 mph.:mad:

[Meteorite]

I'm not sure, it might be the converter locking & unlocking, it's close to a 600-800 rpm difference. I'm running 4.10s in the rear, it's in my SIG.. It shouldn't be doing that at those speeds. :confused: Anyone else.

I thought that the converter locks at a certain speed and not suppose to unlock til it gets below a certain speed, ie:45-55 mph.:mad:
Wow, sorry. I guess I didn't feel like sifting through 27 lines of Signature file to find your axle ratio. My bad.

Since, for the 4R70W, the engine turns 70% as fast in 4th gear as in 3rd (for the same vehicle speed, that is), I would expect more like a 1200 RPM rise for a 4-3 downshift. Therefore, I think it is the converter locking and unlocking.

When you let up off the throttle, the converter is going to lock for efficiency. When you tip back in to the throttle, that is understood by the control system as demand for more tractive effort, and one quick way to get that is to unlock the converter.

[magindat]

I read the signature!

It's not a converter issue.

Carlos, you have a PM.

[magindat]

When you let up off the throttle, the converter is going to lock for efficiency. When you tip back in to the throttle, that is understood by the control system as demand for more tractive effort, and one quick way to get that is to unlock the converter.
While you are correct. That isn't his issue.

[Meteorite]

While you are correct. That isn't his issue.
Would you be willing to tell us what it is, then? I'm curious.:confused:

[dansenander]

Did you have this problem before adding the 4.10's.
Could be speed/Rev limiter?
I know that my speed limiter kicked in at a lower RPM after changing gears. Dennis reflashed the program and problem solved.

Just my .02 cents.

[magindat]

Would you be willing to tell us what it is, then? I'm curious.:confused:

'Bout 90% sure. Still thinkin/confirmin.

[gonzo50]

I read the signature!

It's not a converter issue.

Carlos, you have a PM.


'Bout 90% sure. Still thinkin/confirmin.

Just read your PM, Thanks.
Sorry folks, just trying to confirm the status, will probably take a few days to verify. Thanks for your patience and time.:beer: