Quote:
Originally Posted by geoff270ssf
I want a smarter Cruise Control!! For the life of me I cannot see the difference Tow/Haul makes on our 2015 Georgetown Ford V10. With or without Tow/Haul it downshifts on uphills too soon and stays in the lower gear too long. <<SNIP>>
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Interesting concept. I like it.
Some of what you describe has to do with transmission shift mapping, not cruise control (see my comment on my RAM). Some of the new generation 9 and 10 speed transmissions are criticized for being reluctant to downshift, and some of that reluctance is dictated by a desire to improve fuel economy. Large throttle openings and lower RPM are more fuel-efficient than higher RPM and smaller throttle openings. That logic is applied to pickup truck transmissions. It's hard to know the logic behind a medium-duty truck's automatic, but some of that thinking may bleed over in design.
I also have a hunch that cruise control isn't as adaptable as you wish due to safety regulations. Why? Guessing, but I think varying speed by, say, a 10 MPH range might instigate a lot of unsafe behaviors by other drivers. It's one thing to overtake a motorhome or towable that slows on climbs and picks up speed again once over the top. Other drivers expect a bit of speed variation. But this behavior in a sedan would just piss off other drivers...especially if the once-slow-poke mindlessly speeds up on the downhill when others have an opportunity to pass. This kind of behavior frequently instigates road-rage incidents.
Take it out of a light-duty truck or medium-duty truck (TV or motorhome) and put it in a car or SUV, and these speed changes might be unwelcome and, perhaps, a bit unsafe. A "one-size-fits-all" approach to DOT regs may be the culprit here. So your motor vehicle "auto-pilot" is designed to meet the needs of the largest segment of the driving population.
I live in the mountains, and I drive regularly with "commuters" over terrain with 5% to 7% grades. They do not slow on the uphills. Some do "run free" on the downhills, but that's unwise since all are running 5 MPH or more over the posted limit already, and our roads are heavily "revenued." So maintaining a constant speed is the rule rather than the exception.
My RAV 4 is a 5-speed, so it's behavior is under my control somewhat. If I leave it in 5th, it will slow on climbs and run free (with no upper limit) on descents. In this terrain, I usually put it in 4th and leave it there so my speed DOESN'T vary all over the place.
My RAM 1500 is older (a 4-speed auto), and depending on my electronic OD choice - normal, tow/haul, OD off - the shift mapping will adjust the shift points on climbs and descents. It's sluggish to downshift in normal, so speeds on some climbs will drop by as much as 7 MPH before a downshift, but once it downshifts, it immediately seeks the cruise set speed. On the downhills, it will run free to any speed, but in tow/haul or OD off, it does a better job of holding speed--but it does NOT perform as you'd wish it to.
Between market forces and DOT regs, I suspect your wished-for cruise control might be a great after-market product to modify a light or medium duty truck cruise, but I doubt it would be a good investment for a daily-driver. It's certainly an achievable goal technically.
Perhaps, like Banks performance enhancement products for diesels, a manufacturer could be coaxed to make a plug-and-play add on to a standard cruise control to give it these adjustable parameters.
P.S. Given the number of drivers of import cars who can't figure out to turn off recirculated air when they need to defrost their windows, American cars dumbed-down the HVAC to refuse to engage recirc when defrost is selected. But Japanese cars enable this choice at all times....with the result being that many drivers are fogged up on the inside because they are clueless. Believe it or not, the skill level required to operate your more sophisticated cruise control may be well beyond the capacity of many drivers on the road today...as is an aftermarket electronic tuning device. That could be another reason DOT might limit the design parameters of a factory cruise control
But I love the idea.
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