Is This a Slipping Tranmission? - Ranger-Forums - The Ultimate Ford Ranger Resource


Drivetrain Tech General discussion of drivetrain for the Ford Ranger.

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Old 01-28-2007
this_is_nascar's Avatar
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Is This a Slipping Tranmission?

Today, I noticed something that may or not be a problem. I noticed that it sounded like the engine really "winds-up" from a dead stop, going from 1st to 2nd gear. It goes into gear just fine, but it seems like the engine is revving much higher as it's coming up to speed from a stop. Going thru all the gears, it's nice and smooth, with no jerks, bucking, etc. When I check the dip-stick, it's showing just a tick below the cross-hatched "safe range" for the fluid level.

Do I have a problem?
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Old 01-28-2007
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well atleast you know that its not "excess" fluid! Are the rpms going up?
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Old 01-28-2007
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Pull your battery off for 20 minutes, put it back on and try again.

The transmission controller is continually adaptive. If you've done anything to get on the throttle a lot lately, it will accomodate you by shifting later and later until it hits some predetermined limit.

If you are easy on it, it will shift earlier in general and adjust overal shift quality to that driving style.

It's possible you're just way into the programming and resetting it and letting it adapt in it's "fast learn" mode might get you back to where you were.

The 2-3 "flare" (sudden jump in RPMS as it shifts from 2 to 3) is very common. Many reasons for this but at the root of it is the "found" gear between the old 1 and 2 in the 4 speed transmission. Our second gear is just 1 with the overdrive kicked in.

To go from 2 to 3 requires disengaging overdrive while simultaneously applying another band to get to the next gear. Bit of a critical time/speed issue here hence the common problem.
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Old 01-28-2007
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Thanks John. I had forgotten about the adaptive learning after the battery has been dissconnected. I'll try that first. It's definately not over-filled Scott and after me busting on you yesterday, I wasn't about to add any fluid to it. It's definately shifting smoothly once it shifts. It just seem that it really takes a long time and you can hear the engine wind before that first shift occurs.
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Old 01-29-2007
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John, that seems to have helped. It's shifting much better from 1st to 2nd and is not winding-up as much before shifting.
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Old 01-29-2007
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Give it some time and see how it does I guess. If the problem repeats, you might even have something going on with your TPS (throttle position sensor) as that has a huge influence on shift point and quality.

Also, if it comes back, PM rwenzing (Bob) and see what he says. I believe he has a better handle on the controls than I do (though I'm ashamed to admit it, lol...)
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Old 01-29-2007
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I will add what little I know about the transmission adaptive strategy.

In the 5-speed Ranger automatics with an Intermediate Shaft Speed sensor, the adaptive strategy is used to adjust the line pressure for consistent shifting thoughout the life of the vehicle. There is no adaptive learning aimed at adjusting the shift points or shift feel based on driver habits.

On the basis of various inputs, the strategy calculates an actual shift time and compares it with a table of ideal shift times. The adaptive provides a kind of feedback loop that continually makes incremental pressure changes, pushing the real shift times toward the ideal.

Over time, as the different combinations of VSS, gear and TP are "experienced", the adaptive learning process will fully update Keep Alive Memory (KAM). It shouldn't matter if the vehicle has 100 miles or 100,000 miles or if the driver is aggressive or conservative. The end of adaptation should take the transmission shift times very close to the ideal.

Resetting the PCM erases the learned values in KAM and the transmission defaults to a base table in non-volatile memory. Then the Shift Adaptive/Pressure Control Strategy starts over again, learning the correct pressure for every combination. During the relearn, it is likely that shifting will feel different with shift events that may be harsher than normal or shift timing that may be early or delayed.

~~~~~~~~~~~~~~~~

The 1-2 shift shouldn't be hard to calibrate since it simply engages the overdrive while staying in 1st gear in the Simpson gearset. The bad one is the 2~3 shift that must coordinate the shifting of both the Simpson gearset and the overdrive gearset simultaneously. This is called a "swap shift" and it is anything but easy to calibrate well. To avoid unnecessary driveability problems, the transmission skips the 2nd gear issue entirely by doing a 1-3 at light throttle when 2nd is not needed.

~~~~~~~~~~~~~~~~

OK, having said all that, I must also say that I have owned only manual transmission Rangers. That makes my real world experience level with Ranger automatic transmission behavior very close to zero. The perception, or perhaps the reality, may be different from what I have described above. But that is how it is designed and calibrated to work.
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