Surging/Erratic Adaptive Cruise Control (Copilot Assist/Active)

[Nommpop]

So I was having an issue with my cruise control and after a week of research I found the problem and wanted to share it with everyone as it was pretty difficult for me to find any info about it.

My truck is a XLT 302A that has Copilot Assist and I enjoy using my lane keep and cruse control assistance that it offers. Everything was working great until I did a level kit and 35" tires, which is when my adaptive cruse would surge too much then too little throttle whenever I got behind someone and it needed to adjust my speed. When I was alone, everything worked fine, but as soon as someone was there it would act up.

Well, one step that I did not perform after the modification, was the tire size adjustment after the larger tires. The speedometer would show about 5% lower than my GPS speed and I didn't think much of it. Apparently I was wrong because after finding a hidden page for the 15-20 F150s, it says when calibrating its safety systems, one step is to verify the wheel diameter matches what is in the computer otherwise surging may result. I got out my Forscan and corrected the speedometer, and over the last two days my cruse has not acted up since.

I hope this post is helpful to someone else and it avoids a trip to the dealer for a simple 10 minute adjustment using Forscan.

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[Tall Tail]

You may want to check out this thread
https://www.f150gen14.com/forum/thr...ecalibrate-speedometer-for-bigger-tires.1503/

 

[Nommpop]

You may want to check out this thread
https://www.f150gen14.com/forum/thr...ecalibrate-speedometer-for-bigger-tires.1503/

That is a good source, but what I was trying to explain was if you do not recalibrate your speedo, then you may have cruise control problems. Thank you though

 

[AdamLeon]

Sorry for the late reply, but thank you for this!

I did the same setup last week (2.5" level and 35's), and noticed the surging. I will adjust in Forscan when I get home.

The co-pilot lane keeping also seems to be serving back and forth. Did you also notice this until Forscan?

 

[Nommpop]

Sorry for the late reply, but thank you for this!

I did the same setup last week (2.5" level and 35's), and noticed the surging. I will adjust in Forscan when I get home.

The co-pilot lane keeping also seems to be serving back and forth. Did you also notice this until Forscan?

I did not have any issues with my lane keep.

 

[Reeltime]

Occasionally, I have the swerving back and forth. Usually on the same road, same spot. Haven’t found the issue, road lines seem to be fine. I guess we just have to remember this is not Blue Cruise and still have to pay attention.

 

[SmokinOkie]

This fixed my issue, thank you for posting this!! I was going down the path of the level messed with the radar but after reading your post I used Forscan to change my tire size and then did a relearn on the transmission... Poof, problem gone!

So I was having an issue with my cruise control and after a week of research I found the problem and wanted to share it with everyone as it was pretty difficult for me to find any info about it.

My truck is a XLT 302A that has Copilot Assist and I enjoy using my lane keep and cruse control assistance that it offers. Everything was working great until I did a level kit and 35" tires, which is when my adaptive cruse would surge too much then too little throttle whenever I got behind someone and it needed to adjust my speed. When I was alone, everything worked fine, but as soon as someone was there it would act up.

Well, one step that I did not perform after the modification, was the tire size adjustment after the larger tires. The speedometer would show about 5% lower than my GPS speed and I didn't think much of it. Apparently I was wrong because after finding a hidden page for the 15-20 F150s, it says when calibrating its safety systems, one step is to verify the wheel diameter matches what is in the computer otherwise surging may result. I got out my Forscan and corrected the speedometer, and over the last two days my cruse has not acted up since.

I hope this post is helpful to someone else and it avoids a trip to the dealer for a simple 10 minute adjustment using Forscan.

 

[Nommpop]

This fixed my issue, thank you for posting this!! I was going down the path of the level messed with the radar but after reading your post I used Forscan to change my tire size and then did a relearn on the transmission... Poof, problem gone!

I’m happy to hear that I was able to help somebody else out too!

 

[ChapSm]

Good morning. I have a 2024 Ford F-150 and I just did the Ready Lift 3.5” lift and new wheels. Tire size is now 295/60/R20. My adaptive cruise control keeps surging (speeding up then slowing down) and isn’t running smoothly. Is this the same issue you were having after bigger tires? Thanks!

I’m happy to hear that I was able to help somebody else out too!

So I was having an issue with my cruise control and after a week of research I found the problem and wanted to share it with everyone as it was pretty difficult for me to find any info about it.

My truck is a XLT 302A that has Copilot Assist and I enjoy using my lane keep and cruse control assistance that it offers. Everything was working great until I did a level kit and 35" tires, which is when my adaptive cruse would surge too much then too little throttle whenever I got behind someone and it needed to adjust my speed. When I was alone, everything worked fine, but as soon as someone was there it would act up.

Well, one step that I did not perform after the modification, was the tire size adjustment after the larger tires. The speedometer would show about 5% lower than my GPS speed and I didn't think much of it. Apparently I was wrong because after finding a hidden page for the 15-20 F150s, it says when calibrating its safety systems, one step is to verify the wheel diameter matches what is in the computer otherwise surging may result. I got out my Forscan and corrected the speedometer, and over the last two days my cruse has not acted up since.

I hope this post is helpful to someone else and it avoids a trip to the dealer for a simple 10 minute adjustment using Forscan.

So I was having an issue with my cruise control and after a week of research I found the problem and wanted to share it with everyone as it was pretty difficult for me to find any info about it.

My truck is a XLT 302A that has Copilot Assist and I enjoy using my lane keep and cruse control assistance that it offers. Everything was working great until I did a level kit and 35" tires, which is when my adaptive cruse would surge too much then too little throttle whenever I got behind someone and it needed to adjust my speed. When I was alone, everything worked fine, but as soon as someone was there it would act up.

Well, one step that I did not perform after the modification, was the tire size adjustment after the larger tires. The speedometer would show about 5% lower than my GPS speed and I didn't think much of it. Apparently I was wrong because after finding a hidden page for the 15-20 F150s, it says when calibrating its safety systems, one step is to verify the wheel diameter matches what is in the computer otherwise surging may result. I got out my Forscan and corrected the speedometer, and over the last two days my cruse has not acted up since.

I hope this post is helpful to someone else and it avoids a trip to the dealer for a simple 10 minute adjustment using Forscan.

 

[Nommpop]

Sounds like the same issue to me. Get forscan and update your tire size, I bet it'll smooth out

 

[ChapSm]

Thanks! When adaptive cruise is turned off, the truck acts normal. It’s only when adaptive cruise is enabled that it fluctuates and speeds up/slows down consistently. I have never used forscan, is it easy to use? Is it worth letting the dealership correct? Don’t want to mess anything up lol

Sounds like the same issue to me. Get forscan and update your tire size, I bet it'll smooth out

 

[rugedraw]

Thanks! When adaptive cruise is turned off, the truck acts normal. It’s only when adaptive cruise is enabled that it fluctuates and speeds up/slows down consistently. I have never used forscan, is it easy to use? Is it worth letting the dealership correct? Don’t want to mess anything up lol

You will get mixed answer here, but yes, I think it is easy to use. When I leveled my truck, I had to adjust for the new wheel/tire size, recalibrate the IPMA and CCM to get it work right. However, some people don't have to do anything at all after modifying their truck and everything works fine. I have no good explanation for this, but it is what it is. All 3 procedures (if needed) can be done with FORScan.

 

[ChapSm]

Thanks for the information!! I have never used forscan before and am a little nervous to jump into it. What all do I need to buy to complete this process? Is it somewhat user friendly as well?

You will get mixed answer here, but yes, I think it is easy to use. When I leveled my truck, I had to adjust for the new wheel/tire size, recalibrate the IPMA and CCM to get it work right. However, some people don't have to do anything at all after modifying their truck and everything works fine. I have no good explanation for this, but it is what it is. All 3 procedures (if needed) can be done with FORScan.

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