Cruise control going downhill

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I was on the north end of the Taconic Parkway today which is hilly. I had my Ford set to 60 mph for the cruise control. Works fine until I start to pick up some speed going down hills and then it downshifts from 6 to 5 and maybe to 4 in an attempt to keep the speed at 60. If I was driving with my foot on the gas pedal (it's diesel) I would just let it coast in 6.

I understand the logic, but I would prefer it not do that.
 
Originally Posted By: dishdude
Does it have a manual mode? Can you lock it in 6?


I can also turn off cruise control when going down a hill. Then turn it back on.

If I lock it in 6 I might need to again unlock it going up a steep hill to allow it to downshift.

I guess I feel that cruise control should do the proper thing without me getting involved.
 
Yeah, the logic on cruise isn't perfect. Some vendors implement it better than others.

The. Eat ice driven a reasonable amount (>10k miles) was our 94 Toyota previa. I haven't put 10k on the Prius my parents have, but the cruise doesn't seem as good when I've used it. Could be the hybrid part.

Our Hondas are good, but are still aggressive on the uphill, the old analog cruise on my mb diesel worked well except that sometimes it would "pulse" the fuel rack based upon the motion in the speedo needle (digitized from a spinning cable).
 
Hill decent control

Both of my 4-wheelers have it and the quick and easy mode is to deactivate it. I do it differently on the Ford vs. Honda. I wait on the Honda until the revs rise after a ~5mph increase from the set speed. The Ford gets cancelled at the top of the hill.

The Honda has a cancel button but the Ford requires a tap on the brake to deactivate. Make sure you have tow/haul off in your Ford or it will downshift anyway.
 
I often have to set cruise control on my Focus, that's the only way it will hold speed without riding brakes on the hill. It's a manual, so obviously it's not going to be downshifting on its own.

My parents' escape will act like you describe if it's in sport mode - which, as far as I can tell, functions similar to a tow/haul mode.
 
My CX5 and several other vehicles I've own with AT do the same thing. It is considered a safety feature so the vehicle doesn't "run away" on long steep hills. Ed
 
Originally Posted By: Donald
I was on the north end of the Taconic Parkway today which is hilly. I had my Ford set to 60 mph for the cruise control. Works fine until I start to pick up some speed going down hills and then it downshifts from 6 to 5 and maybe to 4 in an attempt to keep the speed at 60. If I was driving with my foot on the gas pedal (it's diesel) I would just let it coast in 6.

I understand the logic, but I would prefer it not do that.


That's how the modern Fords do it. I agree, it's annoying. I just hit the "Coast" button on a decent downhill run, moderate speed with the brakes if need be, and then hit "Resume" once the road levels out again.
 
My Prius does the same thing, in its way, and so did a friend's 2002(?) Chrysler that I drove. Yes, it's a very annoying and wasteful behavior, and does nothing for safety unless the driver is incredibly inattentive.
 
Doesn't the truck have an exhaust brake? My exhaust brake kicks on when I go too quick while cruising. But only if I turn it on. That's on my cummins though.
 
Originally Posted By: Donald
I was on the north end of the Taconic Parkway today which is hilly. I had my Ford set to 60 mph for the cruise control. Works fine until I start to pick up some speed going down hills and then it downshifts from 6 to 5 and maybe to 4 in an attempt to keep the speed at 60(a). If I was driving with my foot on the gas pedal (it's diesel) I would just let it coast in 6(b).

I understand the logic, but I would prefer it not do that.

Originally Posted By: dishdude
Does it have a manual mode? Can you lock it in 6?

Originally Posted By: Donald
I can also turn off cruise control when going down a hill. Then turn it back on.

If I lock it in 6 I might need to again unlock it going up a steep hill to allow it to downshift.

I guess I feel that cruise control should do the proper thing without me getting involved(c).

(a) It works as designed, you set the speed CC keeps the car at that speed for all street surface/conditions: flat, uphill and downhill.

(b) What will the speed be at the bottom of the hill if you have the transmission at 6th and your foot off the gas pedal ?

(c) How do you like your cruise control to work ? Don't stay with set speed ?
 
I like the feature. Obviously my SRT doesn't have it, but most vehicles with automatics I've owned since the early 90s have that feature. It only kicks in if your speed exceeds about 5 mph over the setpoint. Perfect for avoiding a ticket on a gentle downhill. I remember that a particular software re-flash added that trick to my wife's 93 Vision TSi, and I was blown away at how effective it was. My limited experience with cruise control prior to that car was 80s GM junk that would lag 15 mph below the setpoint on an uphill and then downshift 2 gears and scream... followed by floating 15+ mph over the setpoint on a downhill and making me brake, then have to re-engage the cruise. Naturally the 93 Vision was the first car I had where I actually started USING cruise control.

A diesel is another matter- diesels have virtually no engine braking by reducing throttle to idle- that's the whole reason "Jake Brakes" and other retarders exist- to give a diesel better engine braking comparable to (or in the case of jake brakes, better than) a spark-ignition engine. Downshifting at idle without a retarder on a diesle will only spin the dang thing faster, not actually increase drag like a gasoline engine will when the throttle butterfly is shut.
 
I live in the Mountains and am glad when my CR-V drops a gear going down hill in cruise. If I hit "coast" I would easy pick up 10-20 MPH over the speed limit.

How many guys say, "don't down shift going down hill, bad for tranny, use brakes". But the car does it on its own, how bad can it be? Now that cars "auto brake", I wonder how they control excess downhill speed?
 
If it coasted in 6th, you'd have to hit the brake to slow down and disable cruise control.

The downshifting is the preference of the majority unfortunately. Especially for towing.

Marginal transmission wear outweighs brake related runaways. (Extreme case, but think of the volume Ford sells these trucks at.)
 
Originally Posted By: 440Magnum
I like the feature. Obviously my SRT doesn't have it, but most vehicles with automatics I've owned since the early 90s have that feature. It only kicks in if your speed exceeds about 5 mph over the setpoint. Perfect for avoiding a ticket on a gentle downhill. I remember that a particular software re-flash added that trick to my wife's 93 Vision TSi, and I was blown away at how effective it was. My limited experience with cruise control prior to that car was 80s GM junk that would lag 15 mph below the setpoint on an uphill and then downshift 2 gears and scream... followed by floating 15+ mph over the setpoint on a downhill and making me brake, then have to re-engage the cruise. Naturally the 93 Vision was the first car I had where I actually started USING cruise control.

A diesel is another matter- diesels have virtually no engine braking by reducing throttle to idle- that's the whole reason "Jake Brakes" and other retarders exist- to give a diesel better engine braking comparable to (or in the case of jake brakes, better than) a spark-ignition engine. Downshifting at idle without a retarder on a diesle will only spin the dang thing faster, not actually increase drag like a gasoline engine will when the throttle butterfly is shut.

Diesels engine brake. They engine brake much more than gas-engines. Engine braking is a factor of compression not manifold vacuum.

Jake brakes just engine brake better:

Quote:
A compression release brake, or jake brake, this is the type of brake most commonly confused with real engine braking; it is used mainly in large diesel trucks and works by opening the exhaust valves at the top of the compression stroke, resulting in adiabatic expansion of the compressed air, so the large amount of energy stored in that compressed air is not returned to the crankshaft, but is released into the atmosphere.
Normally during the compression stroke, energy is used as the upward-traveling piston compresses air in the cylinder; the compressed air then acts as a compressed spring and pushes the piston back down. However, with the jake brake in operation, the compressed air is suddenly released just before the piston begins its downward travel. (This sudden release of compressed air creates audible sound waves similar to the expanding gases escaping from the muzzle of a firearm.) Having lost the energy stored within the compressed air, there is no 'spring back' from it so the engine must expend yet more energy pulling the piston back down again.
 
So we don't like that the cruise control is doing the job its designed for - maintaining a set speed? First world problems...

Honestly don't mind the logic - I've driven for decades using engine breaking to help control speed and not burn up the brakes (you know, like a stick shift...). When I lived in Colorado (and return multiple times a year), it was just a standard part of mountain driving - stick or auto. Nice to have the auto think and take care of it...

And if it eliminates the morons who then ride their brakes for miles down mountain grades...
 
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