Normal transmission behavior?

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Apr 13, 2013
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FL, USA
I noticed something seemingly odd when driving the Taurus at speed. You can see when the torque converter locks up around 40-45 mph (when driving conservatively) but anytime you let off the gas while at speed the torque converter unlocks. Once you step back on the gas it locks back up fine and will stay locked.

I changed the transmission fluid today and it behaves just as it did before the fluid change. Neither of our other cars exhibit this behavior.

Wondering if this is normal Ford programming?
 
GMs used to unlock if you tapped the brake, which I thought was odd.
 
I noticed something seemingly odd when driving the Taurus at speed. You can see when the torque converter locks up around 40-45 mph (when driving conservatively) but anytime you let off the gas while at speed the torque converter unlocks. Once you step back on the gas it locks back up fine and will stay locked.

I changed the transmission fluid today and it behaves just as it did before the fluid change. Neither of our other cars exhibit this behavior.

Wondering if this is normal Ford programming?
That is the normal mode of operation for a huge number of transmissions across all different manufacturers. I've always suspected it's to soften the "lunge" of lifting off the throttle and pressing again. If you've driven a manual transmission car you'll understand. On vehicles with drive by wire I don't even understand why it's necessary -- just smoothing out the accelerator input seems easier.

I hate it personally. Some cars are so lazy to lock the converter and you get that RPM flare just before it locks. It just bothers me, I don't know why.
 
That is the normal mode of operation for a huge number of transmissions across all different manufacturers. I've always suspected it's to soften the "lunge" of lifting off the throttle and pressing again. If you've driven a manual transmission car you'll understand. On vehicles with drive by wire I don't even understand why it's necessary -- just smoothing out the accelerator input seems easier.

I hate it personally. Some cars are so lazy to lock the converter and you get that RPM flare just before it locks. It just bothers me, I don't know why.
I don’t care for it either. I understand what you mean by manual transmission feel. That is how our Honda and VW feel, more of a direct connection vs. the slipping feel this has.
 
That's reassuring, thank you for your input.
When you need to worry is when you are keeping a steady pace and the torque converter locks and unlocks without any decrease in speed. The torque converter will usually lock up in the 45 to 50 mph range. If you are running steady above that point and it starts searching, time for the transmission shop.
 
Yep, exactly right ^^^^^^^^^^^^

The 99 Ford Expedition my mom had was jacked up exactly like you stated here.

That darn thing went through 2 trans in less than 130k miles.

Motor was awesome though. Actually... The rest of the vehicle held up extremely well.

Just garbage transmission.
 
Every older Ford I've driven has done that. Even my old Jeep does it too. I think it's good that my father was adamantly opposed to automatic transmissions during that era; my mother is an on-off-on-off-on-off the throttle driver. I'm sure the trans wouldn't like that.

Also on a really cold day, the trans may not lockup at all. I think the fluid has to get to 140f before the computer will lockup the torque converter.
 
I never liked it either. I drove like 10 years before having an automatic, and a lot of miles at that. I was very used to how it felt coasting. Very annoying.

I don’t notice it too badly on my ancient Camry but my now departed Tundra was quite noticeable, probably because it practically idled going down the road—so when the TC unlocked, rpm would climb quite a bit (as it was around stall speed). One thing I learned was to very gently ease into the throttle. If I goosed it too fast it’d unlock. But the programming on that vehicle seemed to reward Uber gentle throttle changes with TC staying locked. YMMV.

I think neither will do lock up if the trans temp is below 100C. Luckily the smaller Camry warmed up real quick.
 
This is my only gripe with my older Ranger. The revving up just to lock back up a second later everytime I have to ease off the throttle drives me bonkers.
 
As everyone else said, this was my experience with older autos. They would unlock if you touched the brake pedal (I thought it was so it wouldn't stall if you locked up the brakes?), and they would also unlock if you let off the gas. Now they keep them locked for fuel economy at the expense of low-speed smoothness. I can appreciate the pros and cons of both approaches.
 
As everyone else said, this was my experience with older autos. They would unlock if you touched the brake pedal (I thought it was so it wouldn't stall if you locked up the brakes?), and they would also unlock if you let off the gas. Now they keep them locked for fuel economy at the expense of low-speed smoothness. I can appreciate the pros and cons of both approaches.

Ahhh that makes sense about the brake integration.

Odd thing, old Chryslers with the 3 and 4 speeds wouldn't unlock until you dropped to about 35 even with your foot on the brake.
 
I think you meant 100F. If it took till 100C to lock up it probably never would under most conditions.
You're right, 100F.

I know mine would unlock for almost any amount of torque through it, and would not lock up below 4th gear (direct drive), not sure what Aisin had against lockup convertors... Was a bit of a rude surprise, after years of hearing how ATF needs to be kept as cool as possible, my Tundra would sit at 180F with the convertor locked, on the highway, once everything stabilized. TC outlet would spike to 230F if I didn't force a downshift on hills! I don't think the thermostat on that trans would allow cooling until 100C or better (it did have an engine coolant - ATF heat exchanger which is why it would sit at 180F on the highway).
 
Ahhh that makes sense about the brake integration.

Odd thing, old Chryslers with the 3 and 4 speeds wouldn't unlock until you dropped to about 35 even with your foot on the brake.
Back when the first Ford automatic overdrive came out for the 1980 model year (called the FIOD then AOD), I remember reading a magazine test where an LTD would stall every time they did a panic stop from highway speeds. Locking the rear tires in overdrive during a panic stop would apparently not unlock the torque converter which killed the engine. If that was a problem inherent to the initial design of that transmission (and not an issue only with the test car) I assume they fixed that problem soon afterwards as that is an obvious safety issue.
 
Transmissions are a funny thing. You can test drive two identical new cars at the dealership with 5 miles on the odometer and it’s possible they will both have slightly different shift characteristics. This was very common with 3 speed automatic and 4 speed automatic transmissions with O/D and TCC. When I buy a new car I always test drive at least two vehicles to get a feel for the vehicles. The transmissions almost always feel different. However, I have noticed that with 6+ transmissions, two identical cars pretty much shift the same now. The complexity of 6+ speed, CVT’s and DCT transmissions require very precise machining and computer software for them to work properly.

With 3 and 4 speed autos you could get one built with slightly loose tolerances and it would still last a good while.

Needless to say, your tranny is probably shifting fine.
 
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