Cruise Question

[Dxlnt1]

Had my first long distance ride this weekend. For those in Cali, I rode over the grapevine. Cruise control set for 80 mph. Held speed going uphill and flat land no problem. But when on the downhill side, the car downshifted all the way to 3rd gear. I assume to try slow car down to set speed. Is this normal? All my other cars just release throttle and car continues picking up speed but never downshifts as the SHO did. Wondering if there is a problem.

FYI, running LMS 4+, 91 octane, oem 19" tires, non ACC

 

[Josephm]

That's normal especially down steep declines, I usually just turn it off and hover over the gas and get the free mpg

 

[bykr]

I don't recall my car ever downshifting.Is it something that can be defeated?

 

[Dxlnt1]

That's normal especially down steep declines, I usually just turn it off and hover over the gas and get the free mpg

It just seemed strange the car would continue downshifting. Maybe just come out of overdrive but all the way to 3rd gear?

And yes, I just canceled it kept it pushing.

I jumped on it a couple times on open road. I think I had too much cargo to get better times and speed, but it was consistent.

 

[BiGMaC]

That is the behavior I have noticed... My service rep told me it's normal.  He said it's designed not only to slow you on downhill, but will downshift at certain speeds on the flat so that when you accelerate it doesn't have to shift in "normal" driving to accelerate.

 

[FoMoCoSHO]

That's normal especially down steep declines, I usually just turn it off and hover over the gas and get the free mpg

On the 2013's at least, that is unnecessary as the car will go into decel fuel cutoff and shut off the injectors. You can see this in Torque when measured AFR goes up to 29.4

 

[glock-coma]

That's normal especially down steep declines, I usually just turn it off and hover over the gas and get the free mpg

On the 2013's at least, that is unnecessary as the car will go into decel fuel cutoff and shut off the injectors. You can see this in Torque when measured AFR goes up to 29.4

I always wondered why the AFR would spike like that on deceleration.  I guess it does it with the 2010 also.

 

[Dxlnt1]

That's normal especially down steep declines, I usually just turn it off and hover over the gas and get the free mpg

On the 2013's at least, that is unnecessary as the car will go into decel fuel cutoff and shut off the injectors. You can see this in Torque when measured AFR goes up to 29.4

I always wondered why the AFR would spike like that on deceleration.  I guess it does it with the 2010 also.

Again, the continual downshift to slow the car can be dangerous and car over rev un necessarily. Seems it would lock out after dropping 2 gears but I dropped 3. Wouldn't let it go anymore as rpm was no at 5000.

Just my thoughts.

That is the behavior I have noticed... My service rep told me it's normal.  He said it's designed not only to slow you on downhill, but will downshift at certain speeds on the flat so that when you accelerate it doesn't have to shift in "normal" driving to accelerate.

Think I noticed that. It felt like the old GM style lockup converters.

 

[BiGMaC]

Again, the continual downshift to slow the car can be dangerous and car over rev un necessarily. Seems it would lock out after dropping 2 gears but I dropped 3. Wouldn't let it go anymore as rpm was no at 5000.

Possible and I feel your concerns, but it's a bit hard to conceive of Ford programming the ECU in a way to allow the car to damage itself.

 

[Brucelinc]

Guys, I don't think the cruise control behavior described here is normal at all.  The owners manual doesn't discuss it and my 2010 MKS most certainly doesn't downshift when going downhill with cruise control engaged.  If the hill is really steep and my speed picks up more than desired, I need to brake to slow it down.  On a long steep hill, rather than ride the brake, I will manually shift to 5th but the cruise control never does that automatically.

Could there have been a version of the LMS 4+ tune that might have enabled this?

From the owners manual:
Note:
• Vehicle speed may vary momentarily when driving up and down a
steep hill.
• If the vehicle speed increases above the set speed on a downhill, you
may want to apply the brakes to reduce the speed.
• If the vehicle speed decreases more than 10 mph (16 km/h) below
your set speed on an uphill, your speed control will disengage. 

 

[BiGMaC]

Guys, I don't think the cruise control behavior described here is normal at all.  The owners manual doesn't discuss it and my 2010 MKS most certainly doesn't downshift when going downhill with cruise control engaged.  If the hill is really steep and my speed picks up more than desired, I need to brake to slow it down.  On a long steep hill, rather than ride the brake, I will manually shift to 5th but the cruise control never does that automatically.

Could there have been a version of the LMS 4+ tune that might have enabled this?

From the owners manual:
Note:
• Vehicle speed may vary momentarily when driving up and down a
steep hill.
• If the vehicle speed increases above the set speed on a downhill, you
may want to apply the brakes to reduce the speed.
• If the vehicle speed decreases more than 10 mph (16 km/h) below
your set speed on an uphill, your speed control will disengage. 

Is your cruise an ACC?.. my '13 doesn't act as the 2010 manual describes, slows down a lot more (down to 25 from 80 for sure), and will even downshift on a flat road.  On a grade if I am following someone the collision avoidance will brake for me.  Do you have "grade assist" ?  I know that DJ had to have it restored by LMS after his tune.

 

[FoMoCoSHO]

Guys, I don't think the cruise control behavior described here is normal at all.  The owners manual doesn't discuss it and my 2010 MKS most certainly doesn't downshift when going downhill with cruise control engaged.  If the hill is really steep and my speed picks up more than desired, I need to brake to slow it down.  On a long steep hill, rather than ride the brake, I will manually shift to 5th but the cruise control never does that automatically.

Could there have been a version of the LMS 4+ tune that might have enabled this?

From the owners manual:
Note:
• Vehicle speed may vary momentarily when driving up and down a
steep hill.
• If the vehicle speed increases above the set speed on a downhill, you
may want to apply the brakes to reduce the speed.
• If the vehicle speed decreases more than 10 mph (16 km/h) below
your set speed on an uphill, your speed control will disengage.

There seems to be a bit of programming differences from gen 4.1 to 4.2

 

[Josephm]

Mine is completely stock and does this. We have some really steep hills, and it does it repetitively especially if i go over one of our passes that is 55MPH; On the way down the flex will not let it coast over 58MPH and downshift to prevent that

 

[Brucelinc]

I do not have ACC or grade assist.  The original poster indicated that he didn't have ACC, either.  There must have been some software differences depending upon build date if some of you without ACC have this cruise control behavior.  Mine is an early 2010 but the 2011 manual says the same thing.  I also recall a few posters who got a version of LMS 4+ that enabled "grade assist" and also changed the way the transmission behaved in manual mode.  This automatic downshifting when going down a steep hill with cruise control engaged is a new one on me.

Here is what the manual says about ACC and use in hilly conditions:
Hilly condition usage
It is recommended that the driver select a lower gear position when ACC
is active in situations such as prolonged downhill driving on steep grades
(i.e., driving in mountainous areas). In these situations, additional engine
braking is needed to reduce the load on the vehicle’s regular brake
system to prevent them from overheating. For more information,
reference Automatic transmission operation in the Driving chapter.
Note: If ACC is applying brakes for an extended period of time, an
audible alarm will sound, the head’s up display will flash and ACC will
shut down. This is to allow the brakes to cool down. When the brakes
have cooled down, the ACC will again function normally.

 

[Dxlnt1]

I do not have ACC or grade assist.  The original poster indicated that he didn't have ACC, either.  There must have been some software differences depending upon build date if some of you without ACC have this cruise control behavior.  Mine is an early 2010 but the 2011 manual says the same thing.  I also recall a few posters who got a version of LMS 4+ that enabled "grade assist" and also changed the way the transmission behaved in manual mode.  This automatic downshifting when going down a steep hill with cruise control engaged is a new one on me.

Here is what the manual says about ACC and use in hilly conditions:
Hilly condition usage
It is recommended that the driver select a lower gear position when ACC
is active in situations such as prolonged downhill driving on steep grades
(i.e., driving in mountainous areas). In these situations, additional engine
braking is needed to reduce the load on the vehicle’s regular brake
system to prevent them from overheating. For more information,
reference Automatic transmission operation in the Driving chapter.
Note: If ACC is applying brakes for an extended period of time, an
audible alarm will sound, the head’s up display will flash and ACC will
shut down. This is to allow the brakes to cool down. When the brakes
have cooled down, the ACC will again function normally.

So with all this, I need to have LMS check if the grade assist was enabled or disabled? Either directly or indirectly.

All my other cars will just allow the car to coast with driver manually downshifting or applying brakes. I do wonder had I not canceled the cruise, would the car have downshifted further? I believe I was at 70-80 mph, 3rd gear, engine at 5000+ rpm. If it would have downshifted again, I may have had to call a tow truck for rest of trip.

 

[Brucelinc]

So with all this, I need to have LMS check if the grade assist was enabled or disabled? Either directly or indirectly.

When in 6th gear, if you shift from Drive to Manual mode and it drops to 5th, the grade assist has been enabled.  If it stays in 6th and the "6" shows up on the display, it is not enabled.  My understanding is that the Flex was set up with "grade assist" from the factory - at least some years of Flex do that.  I do not believe a stock SHO or MKS ecoboost was set up that way.  IIRC, Larrylu had a one version of the tune that gave him the grade assist and another version that did not.  Maybe he will chime in on this.  I think maybe TSS had a change in manual mode functionality with his tune also.  I think it was done to help slow the car after a 1/4 mile pass without overheating the brakes.

 

[DJE624]

I think it was done to help slow the car after a 1/4 mile pass without overheating the brakes.

You are correct Bruce.  I have it too.  I haven't tested it fully yet but what I've seen so far, I like.  If you have an LMS tune, you can request that it be added.  (May take a while since it's not critical.)

 

[Brucelinc]

I remember Rick (when he was at LMS) and I discussed that and I could have gotten it either way.  I decided to keep that part stock knowing that I could always drop to "M" and downshift with the paddles.

 

[Larrylu]

Yes I have both versions. At first LMS wAS not aware of what they had changed. It was a rather benign miscue, and when they figured out how to eliminate THE Grade Assist from the 4+ tune they sent me a revised. I ran the revised for quite a while but I've recently gone back to my original file because I got some weird behavior going WOT in drive from a full stop. Rolling start was ok. My old version of 4+ seems to shift just fine from standing or rolling. Besides I kind of like the Grade Assist functionality.

 

[Dxlnt1]

Yes I have both versions. At first LMS wAS not aware of what they had changed. It was a rather benign miscue, and when they figured out how to eliminate THE Grade Assist from the 4+ tune they sent me a revised. I ran the revised for quite a while but I've recently gone back to my original file because I got some weird behavior going WOT in drive from a full stop. Rolling start was ok. My old version of 4+ seems to shift just fine from standing or rolling. Besides I kind of like the Grade Assist functionality.

Is there a way to limit how far the car downshifts? I would think grade assist only works while in full auto and NOT manual. Or am I wrong?