manually downshifting - is this normal?

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Feb 27, 2017 | 10:23 PM

meborder

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From: Sioux Falls Area

manually downshifting - is this normal?

2006 expedition - 4r75e

When I manually downshift, there is a weird delay going from 2nd to 1st. Going from 3rd to 2nd is normal.

I shot this video tonight to illustrate what I'm talking about. When going from 2nd to 1st, it lets the engine come all the way down to idle before it begins to engage and hold back. It does this at any speed I've tried, though the speeds in this video are about as high as I've manually pulled it down into first.

Is it supposed to do this? Just doesn't seem right...

I've never posted anything to YouTube before, so hopefully the video comes through ok.

Feb 28, 2017 | 04:55 AM

Skauber

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I think mine does the same, but I haven't really paid attention to it.

Mar 1, 2017 | 10:18 AM

alloro

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From: 0,0,1

You can't downshift into 1st if you're going too fast. I think you have to be below 30 MPH for it to happen.

Mar 1, 2017 | 10:51 AM

Mark Kovalsky

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From: SE Florida

That's normal operation for a 4R75E.

Mar 1, 2017 | 10:53 AM

meborder

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From: Sioux Falls Area

Quote:

Originally Posted by alloro

You can't downshift into 1st if you're going too fast. I think you have to be below 30 MPH for it to happen.

Thats what i thought was going on initially, as well.

But it delays downshifting at any speed I've tried. Even if you downshift it around 10-15 mph it still has that delay. I did manually downshift it around 40 mph once, but only once. Watching it go from idle to 4,000 rpm like that is very unnerving.

I've had 2 other vehicles with a 4r70w and neither of them did this. Most recently was my 2000 explorer (v8) and pulling it down into 1st gear it just went in without delay.

I suspect it is doing what it ws programmed to do and the only way to correct it is with a tuner.

Mar 1, 2017 | 10:55 AM

meborder

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From: Sioux Falls Area

Quote:

Originally Posted by Mark Kovalsky

That's normal operation for a 4R75E.

Thanks Mark!

Any idea why? Seems like an odd way to program a manual downshift (to me anyway).

Mar 1, 2017 | 11:33 AM

Mark Kovalsky

Frmr Ford Trans Engr

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From: SE Florida

The 4R75E has it's roots in the old AOD. The AOD made it's debut in the 1979 models. Modern transmission design has fixed most of these delays, but the old design of this trans is just slower to react. I don't think a tuner is going to be able to change it.