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Are There Any Cruise Control Adjustments

 
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  • 2 Post By ProBass
  • 3 Post By _PTGT03
  • 2 Post By GotToGo

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Old 10 Apr 2019, 12:24 pm
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Join Date: Mar 2018
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Default Are There Any Cruise Control Adjustments

Hello all,

I have a 2003 Limited. I use cruise control much more than the average driver. While mine does work, I feel it could be a little more aggressive when going up an incline or hill on the highway.

What I see and feel happening is when I'm approaching a hill or even a slight incline, I can see the speed dropping but yet the cruise is waiting to give more throttle. One the speed drops even lower, the cruise control finally realizes it needs to accelerate but by that time it's too late to gradually do it and it has to accelerate so much that it makes the transmission downshift.

I may be wishing for something that doesn't exist but I am almost positive that if there were an adjustment for this, the cruise would not need to accelerate so hard and the trans downshift unless the car was climbing a steep incline.

Thank You,

Scott D
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Old 10 Apr 2019, 02:38 pm
Handy_Cruiser's Avatar
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Join Date: Oct 2013
Location: Arkansas
Posts: 10,369
Default Re: Are There Any Cruise Control Adjustments

I don't believe there are many mechanical adjustment you can make. The system just pulls on or releases the throttle until the desired speed is reached (plus or minus in a range). No mechanical calibration is needed. It's done with programming. That kind of simple but very effective system is call "elegant" in engineering terms. But it can be crude as well.

To make sure I'm right about this, you can check the service manual. You can download a free copy from my Google Drive at this link:

https://drive.google.com/file/d/0B9C...ew?usp=sharing
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Last edited by Handy_Cruiser; 10 Apr 2019 at 02:41 pm.
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Old 10 Apr 2019, 04:23 pm
Fk5 Fk5 is offline
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Default Re: Are There Any Cruise Control Adjustments

I have never adjusted mine, but the last time that I pulled the upper intake, when I put the throttle cables back on, the one for the cruise control ended up with some slack in it. I do not know if there is any adjustment, if the cable is just slack or something else is messed up. I don't use cruise much, so I haven't worried about it. Check the cable is taut, and maybe lube it.
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Old 11 Apr 2019, 02:46 am
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Default Re: Are There Any Cruise Control Adjustments

Probass; my 2006 non turbo does the same thing. At 65 mph [2500 rpm] and starting to climb a hill, the car drops down to ~62 mph, the throttle increases and the torque converter unlocks, revs go to ~2900, stays there until the top of the hill, throttle backs off, torque converter locks up again. If the electronics were more sensitive [i.e. more throttle at 64 mph], it would act smoother and not have the unlocking occur on medium hills.

At the bottom of certain hills, I give the accelerator pedal a little 'help' to prevent the unlocking.

The 6 speed in the 200's with the 2.4 is worse. It doesn't only unlock the converter, it downshifts into 5th gear for a second. Annoying!
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Old 17 May 2019, 08:26 pm
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Default Re: Are There Any Cruise Control Adjustments

Hello, Thank you for all the responses! I apologize for not returning sooner. Shortly after I posted this I found out my subcontracting job was ending in a week and I forgot about this post. Thank you for the manual Handy_Cruiser! I just searched it and I cannot find anything about cruise control adjustments. The manual I'm sure will come in handy for any future issues I might have.
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Old 19 May 2019, 03:23 am
_PTGT03's Avatar
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Default Re: Are There Any Cruise Control Adjustments

Quote:
Originally Posted by ProBass View Post
Hello all,

I have a 2003 Limited. I use cruise control much more than the average driver. While mine does work, I feel it could be a little more aggressive when going up an incline or hill on the highway.

What I see and feel happening is when I'm approaching a hill or even a slight incline, I can see the speed dropping but yet the cruise is waiting to give more throttle. One the speed drops even lower, the cruise control finally realizes it needs to accelerate but by that time it's too late to gradually do it and it has to accelerate so much that it makes the transmission downshift.

I may be wishing for something that doesn't exist but I am almost positive that if there were an adjustment for this, the cruise would not need to accelerate so hard and the trans downshift unless the car was climbing a steep incline.

Thank You,

Scott D

Hi, I can answer this. So the cruise control is a P+I control device which means proportional plus integral. The engineers programmed a one-sized fits all controller that is 'safe' and would work on all chrysler products of that era. Ideally the control software for cruise control would be precisely programmed for the engine's power, the weight of the vehicle, and how aggressive it could be while satisfying the engineer's Noise Vibration and Harshness specifications for the vehicle. However, fat chance on that one !

The software parameters is loaded into the PCM from the factory, it's not change able. What you're wanting to adjust would be called the proportional gain. That's the rate at which the control system drives the accelerator adjustments to get to the speed (set point). The reason why it's set so slow is because the control system doesn't want to overshoot the set point when accelerating. When the car is on cruise and sees a load, that's an error and the control system wants to correct it.

A more advanced control system which is used on modern cars is the PID controller which stands for proportional+integral+derivative mode. If you're a process engineer and an electrical engineer, you could buy yourself a PID controller and program it to work within the car's system, and integrate the canbus signals through an interpretive bus through something like an arduino set to read canbus. Then you would have to do something called 'process loop tuning' using the Ziegler–Nichols method, in conjunction which can be done on a chasis dyno to get a very responsive and accurate control system. If you ever drive a newer Mercedes or Audi, you can tell how smooth and accurate their cruise control systems are... they're all using PID.
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Old 19 May 2019, 08:50 pm
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Default Re: Are There Any Cruise Control Adjustments

That's what I was going to say.
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Old 23 May 2019, 03:35 pm
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Default Re: Are There Any Cruise Control Adjustments

I was into first generation (1996 to 2000) Chrysler Sebring convertibles before I owned a PT Cruiser. I had 5 of them over the years. The cruise control on every single Sebring I owned was dead on accurate. I wonder if that was a P+I device too.

Quote:
Originally Posted by _PTGT03 View Post
Hi, I can answer this. So the cruise control is a P+I control device which means proportional plus integral. The engineers programmed a one-sized fits all controller that is 'safe' and would work on all chrysler products of that era. Ideally the control software for cruise control would be precisely programmed for the engine's power, the weight of the vehicle, and how aggressive it could be while satisfying the engineer's Noise Vibration and Harshness specifications for the vehicle. However, fat chance on that one !

The software parameters is loaded into the PCM from the factory, it's not change able. What you're wanting to adjust would be called the proportional gain. That's the rate at which the control system drives the accelerator adjustments to get to the speed (set point). The reason why it's set so slow is because the control system doesn't want to overshoot the set point when accelerating. When the car is on cruise and sees a load, that's an error and the control system wants to correct it.

A more advanced control system which is used on modern cars is the PID controller which stands for proportional+integral+derivative mode. If you're a process engineer and an electrical engineer, you could buy yourself a PID controller and program it to work within the car's system, and integrate the canbus signals through an interpretive bus through something like an arduino set to read canbus. Then you would have to do something called 'process loop tuning' using the Ziegler–Nichols method, in conjunction which can be done on a chasis dyno to get a very responsive and accurate control system. If you ever drive a newer Mercedes or Audi, you can tell how smooth and accurate their cruise control systems are... they're all using PID.
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