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Old 09-23-2020, 09:30 AM   #1
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THOR #17298
Angry Mountain Driving Issue

Driving from St. Louis to San Diego had no problemS until I was going down the mountain from Flagstaff to Phoenix. 8% slope. I had it in drive with tow-haul button engaged. I was trying to keep a steady speed Downhill when transmission seemed to disengage and accelerator was making engine rev a lot. Pulled over and tried to change gears and it just bucked and continued to rev. Ended up having it towed to a Ford/RV dealer in Dewey AZ. They say there is nothing wrong with it. What did I do wrong? Afraid to try to drive it down to a Phoenix.
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Old 09-23-2020, 10:11 AM   #2
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Tow Haul switch will shift to a lower gear increasing engine RPM

At the same time feather or pump brakes as needed to control your speed keeping the RPM in houtarget range

It didn't disengage or your RPM wouldn't have went up

Test it on flat land, sounds like it is working
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Old 09-23-2020, 10:17 AM   #3
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Mountain Driving

Thanks. It got very hot and something smelled like it was burning. I had not been driving downhill that long and had not rode my breaks for them to be hot. Every time I hit the breaks after it started bucking it would rev up.
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Old 09-23-2020, 10:24 AM   #4
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Use the brakes harder and slow down until the engine RPM is in your target range

Smell is probably brake pads

Start the decent at a slower speed

I start down a pass at the same speed and gear I came up it in
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Old 09-23-2020, 10:26 AM   #5
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Originally Posted by eenie34@hotmail.com View Post
Thanks. It got very hot and something smelled like it was burning. I had not been driving downhill that long and had not rode my breaks for them to be hot. Every time I hit the breaks after it started bucking it would rev up.
When you hit your breaks going down hill, that is a signal you are trying to slow down and / or maintain speed. As a result the transmission will downshift. When it does, engine RPM's go up. The ECM (the onboard computer) should prevent it from over-revving and hitting a redline condition on the tachometer.
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Old 09-23-2020, 12:08 PM   #6
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Judge is right: Tap the brakes to downshift.
But...
You can sometimes find yourself feeling as if the engine is revving too high.
The computers won't let it commit 'Overrev Suicide".
But I could never resist dropping out ot Tow/Haul mode every once in a while, and letting the transmission regain it's composure.
And I'd start the process all over again.
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Old 09-23-2020, 12:28 PM   #7
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The computer will use the full RPM range of the engine when in tow mode to hold the vehicle and that is normal.
My previous rig was a V8 F150 with 10 spd towing a 9000lbs camper and when going downhill the transmission would downshift and if you let it it would go all the way to 6000rpm.
I didn't like that so I would use the breaks to keep the revs. at 4500rpm.
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Old 09-25-2020, 11:18 PM   #8
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I want to thank everyone who gave me advice about driving in the mountains with my Fourwinds Class C 23U it was very helpful and it backed up what the dealer told me. He actually took me for a drive to help me understand how to use the transmission on my trip. I actually ended up just leaving it in drive and topping each ascent at the speed I wanted to go down the mountain and that worked well. We are continuing the trip to San Diego with a lot less stress. You all are the best!
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Old 09-28-2020, 08:00 PM   #9
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Personally I would have maintained the same speed downhill as I could maintain uphill on the same hill. At 8% that would be about 35-40 mph in 2nd Gear. JMO.
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Old 10-03-2020, 07:11 PM   #10
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Originally Posted by eenie34@hotmail.com View Post
I want to thank everyone who gave me advice about driving in the mountains...... We are continuing the trip to San Diego with a lot less stress. You all are the best!
If that is a scary drive for you.we have made that trip....
then you don't want to do I-70 west into Denver...that will get your attention quickly...and you must trust your transmission to do the job for you..if you ride your brakes too much you will burn them up ! As Bob and Judge said...if you must scrub off speed...tap the brakes

have fun ..

Ron
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Old 10-03-2020, 08:55 PM   #11
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Two other things you can try:

1. Manually downshift to 4. Tow/haul and brake jabbing work in 4, but not in 2.

2. Set cruise at a relatively low speed (40ish). With tow/haul in D it sometimes works fine.

The V10 will go up to about 4,200. It is happy there.

The trans control is adaptive. It will improve after a few downgrades.

Works fine for me on many mountain passes I need to traverse to go anywhere...pulling Cherokee behind Georgetown 30x3 I load to full 18K.

From manual:
“ Automatic Transmission AdaptiveLearningThis feature may increase durability andprovide consistent shift feel over the lifeof your vehicle. A new vehicle ortransmission may have firm shifts, softshifts or both. This operation is considerednormal and will not affect function ordurability of the transmission. Over time,the adaptive learning process will fullyupdate transmission operation.Forced Downshifts•Allowed in drive (D) with the tow/haulfeature on or off.•Press the accelerator pedal to the floor.•Allows transmission to select anappropriate gear.” (PS: I don’t find pressing accelerator causes downshift. But jabbing brake does.)
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Old 10-03-2020, 08:59 PM   #12
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Originally Posted by Judge View Post
When you hit your breaks going down hill, that is a signal you are trying to slow down and / or maintain speed. As a result the transmission will downshift. When it does, engine RPM's go up. The ECM (the onboard computer) should prevent it from over-revving and hitting a redline condition on the tachometer.
Tach on F53 doesnít have a redline.
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Old 10-04-2020, 12:13 AM   #13
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...But the engine does.
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Old 10-04-2020, 12:21 AM   #14
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Tach on F53 doesnít have a redline.

Bob is correct..... the tach may not have a visible redline but there is a rev limiter in the ECM to protect the motor.
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Old 10-04-2020, 12:38 AM   #15
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The V-10 won't blow up... but sometimes it's easy to forget that fact!
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Old 10-04-2020, 01:32 AM   #16
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Quote:
Originally Posted by IDguy View Post
Two other things you can try:

1. Manually downshift to 4. Tow/haul and brake jabbing work in 4, but not in 2.

2. Set cruise at a relatively low speed (40ish). With tow/haul in D it sometimes works fine.

The V10 will go up to about 4,200. It is happy there.

The trans control is adaptive. It will improve after a few downgrades.

cut...
I've actually noticed this; particularly crossing the state of TX. I used my foot almost all the way from San Antoine to Ft Stockton. Somewhere along the way, I put the cruise back on. There were still grades but the transmission didn't downshift. I thought to myself, 'Holy crap, this thing is learning'.

After 4mths in AZ will the battery disconnected, that learning was lost for good.
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Old 10-04-2020, 01:41 AM   #17
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It will re-learn, give it a chance.
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Old 10-04-2020, 02:12 AM   #18
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It is working like it should. When you tap your brakes, it downshifts to a lower gear like it should. Start down the hill much slower in a gear that will keep you near that speed using your brakes very little.
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Old 10-04-2020, 04:49 AM   #19
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Originally Posted by Bob Denman View Post
...But the engine does.
No idea what you are posting about. Please use ď quote replyĒ.

But if it was about the fact the tach does not have a redline it is for two reasons: the engine is designed for high rpm and the engine computer wonít let it overspeed.
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Old 10-04-2020, 11:50 AM   #20
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Quote:
Originally Posted by Bob Denman View Post
Judge is right: Tap the brakes to downshift.
But...
You can sometimes find yourself feeling as if the engine is revving too high.
The computers won't let it commit 'Overrev Suicide".
But I could never resist dropping out ot Tow/Haul mode every once in a while, and letting the transmission regain it's composure.
And I'd start the process all over again.
I do this same thing as we have done most of our travels through the mountains of western NC , Va, and WV. Just disengage the tow/button and start over again. Iím only pulling 3500 itís so on flat hiways I donít even engage the tow/ haul button.
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