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Discussion Starter #1
Strange question, I know, but bear with me. I've noticed a strange shift activity when climbing a couple relatively steep streets near my neighborhood:

  1. Start to climb hill at ~30mph, manually shift down to 3rd, RPMs hit ~2000
  2. Hill steepens, Jeep automatically shifts down to "2nd", RPMs hit ~2500
  3. Slow down for corner (raise foot a bit), Jeep automatically upshifts to 3rd, RPMs hit ~2000 again, starts to bog
  4. Manually shift down from [3], dash reads [2], RPMs hit ~3300
So what gear was I in in step 2?? There's a VERY notable difference between what's below 3rd gear when the Jeep downshifts vs when I do it manually. And it's not 1st gear; I've shifted to [1] manually to check and it's absolutely another kick down.

* all MPH/RPMs are estimated, will get hard RPM/MPH numbers if needed
 

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From my understanding, those manual shifters are the max gear it will be in, not what it actually is in. Thats why it shifted down. Just like turning overdrive off still uses all your gears, except overdrive.
 

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Overdrive

I apologize, I miss read or miss understood, probably more likely I misunderstood. Please delete my answer, and I apologize for adding to the confusion.
 

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Discussion Starter #4
I understand why it shifted down. My question is why it shifted down to what appears to be a whole new gear below 3rd.

fernin, you're saying that there's OD gearing between 2 and 3? That the Jeep shift to a 2.5th gear in step 2? That makes sense, and kinda what I was thinking, but I assumed OD was a top-end gear only.
 

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Discussion Starter #6
How does that happen? Is it "bad"? I can repro this 100% on one particular hill, and can climb the hill in this pseudo-2nd gear if I don't let up on the throttle.
 

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How does that happen? Is it "bad"? I can repro this 100% on one particular hill, and can climb the hill in this pseudo-2nd gear if I don't let up on the throttle.
it's not bad at all; completely normal. the lockup means the wheels are directly driven by the engine just like a manual trans with your foot off the clutch. it's more efficient and it's how most automatics work. when it's not locked up, there is loss in the drivetrain and the RPMs are higher. this is similar to slipping the clutch in a manual.

for instance, when you're at a stop light in an auto, the torque converter is not locked up, otherwise the engine would stall because the wheels aren't moving. when you're on the highway, it will lockup to get you the best fuel efficiency.

i've seen other threads where people have noticed two distinct ratios in 2nd gear for the 5AT. the assumption is that the torque converter is programmed to lock up in certain conditions, which is more noticeable in 2nd.
 

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Discussion Starter #9
So it sounds like maybe the AT is slipping the converter a bit, allowing the revs to rise and gain a little more short-term torque, yet staying "technically" in 3rd gear. When I manually shift to 2nd, however, the gear physically changes and the converter locks in?

This makes a lot of sense as well, since the pseudo-downshift in step 2 is very smooth and subtle.

So far we have mystery OD gearing between 2 and 3, and self-induced converter slippage on the table. I'm leaning toward the latter. :)
 
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