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| 08-07-2015, 12:25 PM | #1 |
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Cruise control jerky on downhills?
Has anyone experienced a 'jerkiness' to the cruise control on downhill runs? it's like the algorithm is too abrupt in throttle inputs (coming off the throttle, in this case).
I noticed it on some long downhills on the 15 between Vegas and Provo, Utah on my way to/from Park City last month. Finally remembered to post something about it as my warranty expires in 8 days... Thanks!
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 '19 X3 M40 Carbon Black/Oyster, '23 Jeep Grand Cherokee L Summit, Past BMWs: '18 M550i, '18 330 GT, '16 X5 40e, '11 E90M3, '06 X5 4.4, '03 330i ZHP, '02 M3, '97 Z3 2.8, '95 M3 (2x), '94 530i (manual), '92 525i (manual), '88 M3, '87 325iS |
| 08-07-2015, 12:33 PM | #2 |
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It's like that with any cruise controlled car I've owned and driven in. I figure it's normal? :shrug:
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| 08-07-2015, 03:35 PM | #3 | |
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'19 X3 M40 Carbon Black/Oyster, '23 Jeep Grand Cherokee L Summit, Past BMWs: '18 M550i, '18 330 GT, '16 X5 40e, '11 E90M3, '06 X5 4.4, '03 330i ZHP, '02 M3, '97 Z3 2.8, '95 M3 (2x), '94 530i (manual), '92 525i (manual), '88 M3, '87 325iS |
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| 08-07-2015, 03:50 PM | #4 | |
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2011 e90 M3 Space Grey DCT ZCP- eAs, BMW Performance, Agency Power, Macht Schnell, iND, Milltek, Volk, Challenge, Stoptech, Ohlins
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| 08-08-2015, 12:13 PM | #5 |
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I'd agree that its a bit jerky. It's not horrible, but very noticeable compared to my 08 VW which is extremely smooth.
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| 08-09-2015, 01:21 PM | #6 |
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Drives: 2008 Jet Black M3 Coupe
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Location: Yucca Valley, CA - Kelowna, BC
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It doesn't want to cruise.
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| 08-10-2015, 09:03 PM | #9 | |
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'19 X3 M40 Carbon Black/Oyster, '23 Jeep Grand Cherokee L Summit, Past BMWs: '18 M550i, '18 330 GT, '16 X5 40e, '11 E90M3, '06 X5 4.4, '03 330i ZHP, '02 M3, '97 Z3 2.8, '95 M3 (2x), '94 530i (manual), '92 525i (manual), '88 M3, '87 325iS |
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| 08-12-2015, 12:23 PM | #10 |
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Just drove my new (well, new to me
 ) e90 m3 from Seattle to Socal and I can confirm this happens. My best guess is that our engines are very torquey and there is no real "gentle" throttle response. Have you tried staying at exactly the same MPH manually while going downhill? It's next to impossible to do so while holding your foot on the accelerator - you will back off constantly. This is what cruise control is doing. It has to back off and because of the amount of torque the engine delivers at all rpm ranges, it's not a smooth transition like in a less beastly vehicle.  Not science, just my humble opinion. Edit: I also imagine if you are in a lower gear where the engine is at a higher rpm, you will see less jerkiness. Thinking this only happens where the throttle has to choose between full idle or just a little gas.
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Last edited by TechNerd; 08-12-2015 at 02:45 PM.. |
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