Adaptive Cruise Control (ACC) On or Off

[danleininger]

One of my frustrations with the Adaptive Cruise Control (ACC)/Collision Mitigation System (CMS) on my ‘19 MA, Spartan Chassis, is the constant speed changes and the unnecessary application of the Exhaust Brake that happens at the bottom of nearly every hill I encounter.

This system is pretty amazing, but it’s not perfect. It does a good job of maintaining a safe distance between the MH and other vehicles and coupled with the Collision Mitigation System (CMS) also preemptively brakes when necessary.

So here’s my concerns:
1) I will find myself suddenly driving slower than expected because of the speed of the vehicle in front of me. The the ACC slowly decelerated the MH, as designed, but it’s deceleration was so slow I simply didn’t notice change.
2) The ACC won’t allow me to change the “set” speed using the Cruise Control “Accelerate” Button if the CMS detects a vehicle within about 500 feet in front of me.

Here’s my Fix:
On my last trip I set the ACC distance to “Disabled” and discovered that the Cruise Control operated more to my liking. This stopped the subtle slowing that occurs when you approach a slower vehicle and I have uninterrupted control of the set speed of the Cruise Control. However the CMS still “Alerts” me when I get too close to the vehicle in front of me. So now I am able to approach a vehicle that I intend to pass much more closely as the ACC hasn’t slowed me down. It’s hard to start to pass someone when you 350 feet back. My CMS Alert still goes off at about 150 feet when driving highway speeds.

Another benefit seems to be the system no longer triggers the Exhaust Brake at the bottom of most hills. I’m assuming somehow the CMS sees the road surface and somehow this triggers the Exhaust Brake. This is annoying because it causes unnecessary braking and then acceleration at the bottom of most hills, plus it’s waste of fuel.

So my question is this: Anyone else driving with the ACC in the Disabled Mode?

[ewlee]

Originally Posted by danleininger

One of my frustrations with the Adaptive Cruise Control (ACC)/Collision Mitigation System (CMS) on my ‘19 MA, Spartan Chassis, is the constant speed changes and the unnecessary application of the Exhaust Brake that happens at the bottom of nearly every hill I encounter.

This system is pretty amazing, but it’s not perfect. It does a good job of maintaining a safe distance between the MH and other vehicles and coupled with the Collision Mitigation System (CMS) also preemptively brakes when necessary.

So here’s my concerns:
1) I will find myself suddenly driving slower than expected because of the speed of the vehicle in front of me. The the ACC slowly decelerated the MH, as designed, but it’s deceleration was so slow I simply didn’t notice change.
2) The ACC won’t allow me to change the “set” speed using the Cruise Control “Accelerate” Button if the CMS detects a vehicle within about 500 feet in front of me.

Here’s my Fix:
On my last trip I set the ACC distance to “Disabled” and discovered that the Cruise Control operated more to my liking. This stopped the subtle slowing that occurs when you approach a slower vehicle and I have uninterrupted control of the set speed of the Cruise Control. However the CMS still “Alerts” me when I get too close to the vehicle in front of me. So now I am able to approach a vehicle that I intend to pass much more closely as the ACC hasn’t slowed me down. It’s hard to start to pass someone when you 350 feet back. My CMS Alert still goes off at about 150 feet when driving highway speeds.

Another benefit seems to be the system no longer triggers the Exhaust Brake at the bottom of most hills. I’m assuming somehow the CMS sees the road surface and somehow this triggers the Exhaust Brake. This is annoying because it causes unnecessary braking and then acceleration at the bottom of most hills, plus it’s waste of fuel.

So my question is this: Anyone else driving with the ACC in the Disabled Mode?

Like you,I noticed the coach slowing down when approaching a car in front of me. All of a sudden I would look down at my speed and notice I was slower than I wanted to be. How did you disable ACC distance? I have Freightliner but the steps should be close to yours.

[Dutch Star Don]

The system is working as designed.....both my truck and car do the same thing. I find it annoying when it slows me down because there is a car in front of me, then some idiot dives in between us, causing my car or truck to brake. I guess it's just the nature of the beast, but it looks like you found a way around it.

When you say the coach slows at the base of a grade.....does that mean if the cruise is set a 60, it slows below that? If you're not aware, even the coaches without ACC or crash mitigation, will slow the coach when the speed exceeds 6-8 mph over the set cruise speed. That can be adjusted to 2-3 mph, the way I prefer it.

[ExRiveter]

On the Freightliner dash, you should be able to select standard cruise control. It was among the options in the menu for cruise control. One can select the distance the ACC will maintain or leave ACC and go to standard cruise control. I also found that the gradual slowing in ACC was hard to notice and never use it any more. The system still monitors the distance between the coach and the vehicle in front, though. It will set off an audible alarm if you get too close that can startle one when preparing to pass. Ask me how I know....
Bob

[danleininger]

Originally Posted by Dutch Star Don

When you say the coach slows at the base of a grade.....does that mean if the cruise is set a 60, it slows below that? If you're not aware, even the coaches without ACC or crash mitigation, will slow the coach when the speed exceeds 6-8 mph over the set cruise speed. That can be adjusted to 2-3 mph, the way I prefer it.

Don, The situation I’m speaking of are the gradual grades where the MH hasn’t increased speed not the larger grades (4%) where the MH accelerates to the point where the Exhaust Brake automatically engages.

On gradual grades as I approach the bottom of grade my Exhaust Brake will engage slowing me down several mph below the set point of the Cruise Control. Then the ACC kicks back in and the goes to 100% power to bring the MH back to speed. Very inefficient for MPG. Happens every time. I’ve learned to overcome this annoyance by applying a small amount of pressure to the gas peddle. This overrides the Exhaust Brake function.

You mentioned reducing the set point for the Exhaust Brake down to 2-3mph above the Cruise Control set point. How did you accomplish this? My set point is nearly 10 mph above the Cruise set point.

[danleininger]

Originally Posted by ewlee

Like you,I noticed the coach slowing down when approaching a car in front of me. All of a sudden I would look down at my speed and notice I was slower than I wanted to be. How did you disable ACC distance? I have Freightliner but the steps should be close to yours.

You should have the ability to change the Following Distance on your ACC. In that menu I have a “Disable” option. That turns off the “Adaptive” function of my Cruise Control.

[Dutch Star Don]

Dan....send an email to Cummins about your issue. Often there is a parameter that can be changed in the ECU. That's how I found out you can change the speed that the engine brake engages when you start down a grade. Have them detail the change if there is one, then you just need someone with an Incite computer to make the changes.

[ArtJoyce]

DW had a gas sipping Subaru. It has the Eyesite and adaptive cruse control. The adaptive cruse applying brakes going down hills and the Eyesite applying brakes when someone passes me and pulls over with little distance.

I could not drive a MH with this going on. But once I get to the hills I don't use cruse because I like to get a running start at the next hill.

[danleininger]

Originally Posted by Dutch Star Don

Dan....send an email to Cummins about your issue. Often there is a parameter that can be changed in the ECU. That's how I found out you can change the speed that the engine brake engages when you start down a grade. Have them detail the change if there is one, then you just need someone with an Incite computer to make the changes.

Don, Would that be a Cummins issue or a Spartan issue?