Odd Powershift behavior....

[macdarren]

I am now learning about my new PowerShift and noticed something odd the
last few days. My drive to work has a couple long fairly steep grades. I usually use the cruise control and set it about 65MPH. What I notice is that the car shifts down to I assume 5th as we start up the hill, but here is the odd part I can feel and if I watch the tach the engine revving slightly up and down. RPM moved from about 3000 to about 3250 and back like you were taping the accelerator with the car in neutral. This seems complete contrary to my understanding of how the PowerShift works.

When it is in gear I assume it has basically 3 states not counting that microslip thing it does. One clutch or the other should be engaged or neither is as it moves from one gear to the other. I would not expect the engine to be able to rev 'freely' 250RPM while the thing is in gear. The clutch must be disengaging for the engine to rev....I don't really feel much in the way of the car speeding up or slowing. I tried hill mode but it does the same thing. It is almost like the PowerShift is wanting to shift up or down for a moment then changes it's mind then 2 seconds later starts over.

It is not bad since you can only really hear it or see it on the tach not feel it much. Has anyone else seen this....if what I think is happening is the car it can't be good for the clutches. I have tried several different speeds and using the accelerator to hold speed instead of the cruise but the little rev jumping is always present on these hills, and I think it even does it on lesser grades just that it is more like 100RPM and is even harder to see or feel.

[billnchristy]

I do believe it can let some slippage occur.

[dan-c]

Was it slightly accelerating and decelerating as the RPMs were moving?

[macdarren]

Originally Posted by dan-c

Was it slightly accelerating and decelerating as the RPMs were moving?

Not that I could feel or see on the speedo. The RPM up and and back happens fast like the engine is not connected to the drive train for a moment accelerates up a few hundred then reconnects and drops back. Up and back takes maybe 2 seconds at most then repeats a couple seconds later.

[wmussatto]

If you are climbing steep hills, hit the "hill mode" button on the side of the shifter. That's what its there for. Unless you are trying for a hypermileing goal, use it.

[Iceracer]

I've noticed something like that. I believe it is because both clutches are released so the revs go up. Sort of a hesitation between shifts. I happens so seldom that I don't worry about it. Going up a hill would make it more noticeable.

[PowerShift]

This transmission does all sorts of weird things early on because it's still literally figuring itself out. My experience and that of many others is that it smooths out over time, or maybe we all just get used to it.

That said I still have a hard time imagining how this unit will last the 150,000 miles Ford says it will with all the pressure daily driving puts on it.

[Reddog99]

I'm guessing that the transmission is shifting between 5 & 6 repeatedly, which would not be unusual in the right conditions. If one of the clutches really is slipping then something is wrong. As a test, do as wmussatto suggested and press the hill button. This will lock out 6th gear. If it still "slips", and you're sure that it's not just downshifting to 4th, then you should visit the dealer.

[macdarren]

I have tried the hill button but it makes no difference in this behavior.

I am pretty sure it is not a 5/6 shift and shift back, especially as the hill button is supposed to lock out 6th. Possible it is a 4/5 shift and back. Since the car has no indicator of the current gear it is hard to tell where it is....I will try the hill a different speed and see what happens, perhaps it is right on the edge of something at 65 so 60 or 75 might make it want to stay in one gear if that is what it is doing. If that is the case I am pretty sure it never completes the shift as I would expect the RPM difference from 4 to 5 is more than the 250RPM but I don't know that, I'd have to find a gear ratio table and calculate it.

[macdarren]

Okay I watched it on the way home and ran a few different speeds.

Here is what I saw: My PowerShift always has this behavior to some extent. No matter the speed or the grade. Even on a flat road any constant speed results in a slight fluctuation in the RPM. On a flat road it is maybe 100 up and down up and down. On a steep grade it is more like 200-300. The vehicle speed remains constant. It doesn't seem to matter if I hold the speed or let the cruise do it.

It doesn't overly concern me at this point. The car may still be learning with only 200 miles since the last battery disconnect and just 325 total. I am more curious than concerned since I don't understand how the transmission can even do this (unless a clutch is engaging on and off or slipping). I don't think it is actually set up to slip a clutch like a manual driver might but rather quickly modulates it to achieve its normal slipping effect. But I really doubt it would do this in a steady state. Does anyone else see this or maybe really know the technicals of the PowerShift and could offer an explanation.