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11-08-2012, 05:38 PM | #1 |
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Limp Mode
Over the weekend my father and I took out his Z4 35is for some "Weekend Driving." The Z is completely stock and freshly out of a once over at the dealer.
After a few minutes of heavy spirited driving, the car would go into "Limp Mode." First time we stopped and let the car cool off for two heat cycles, and the switched the car off. Once we started it up, the car was completely fine. So off we went, switching the car back into Sport+ and continuing in our weekend driving fashion. After another few minutes the car switched itself back into limp mode. This time we stopped and switched the car off and back on, and everything was fine again. We decided to tone it down and go on about our way. We made it back home without any issues and no more limp mode. So on to my question, is there a way to find out what made the car switch itself into limp mode? There weren’t any warnings or check engine light. We would just like to know if there is something wrong with the car. It always felt strong up to when it would go into Limp Mode, and it always felt strong after we would restart it. Jim |
11-08-2012, 06:18 PM | #2 |
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There are a lot of threads on this (non of which I can find right now), especially on performance oriented forums like 1 series and 3 series.
My understanding is that oil temperature (indicated by the dial under the tach) and water temperature are the causes of limp mode. For the oil temp, ~290F is the start of limp mode and there is power reduction before that. The cooling systems on the 35i models and Z4 35is can be overwhelmed even with street driving so I don't think anything is "wrong" other insufficient cooling from the factory relative to the 1M and 335is. This was a disappointing finding for me as well. |
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11-08-2012, 07:55 PM | #3 |
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Thanks for the reply Nick. We were pretty disappointed in the reaction of the car. We have put the car through much harder paces for much long on much warmer days and the car never skipped a beat which is why we were so confused when this happened. I was aware of the overheating issues of the Z but I thought BMW had changed/fixed the problem with the 35is but adding a oil cooler? I was keeping an eye on the oil temp while I was driving and to be honest the temp never real rose over 250ish which I wouldn’t think was too hot, but who know.
It really is amazing how much the computer is evolved in the Z. Jim |
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11-08-2012, 09:41 PM | #4 |
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http://www.e90post.com/forums/showthread.php?t=412156
Check out that post, especially the theory about volatility in coolant temps, and how some people in the table got limp mode even with oil temps hovering around an indicated 250F Turns out neither the Z4 35i or 35is have the auxiliary radiator in the driver side wheel well or larger 850W cooling fan that the 1M and 335is get and enthusiastic drivers end up stuck with limp mode and power reduction even on the street. Frankly, the 5% that I am driving really hard I have a small regret for not getting a true all out performance car like a Porsche or vette Z06. Z is my daily though, so 95% of the time it is a lot of fun to cruise around in. |
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11-08-2012, 11:44 PM | #5 |
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Mine did this on a 2000 mile road trip. First time it was when I floored the accelerator and the engine light came on and then when I turn the engine off it went out again. It went to the dealer and they couldn't replicates the issue again. I had to physically drive the car and really floor the accelerator hard for the problem to come up again. It turns out it was a sticking valve on one of the turbochargers. This was replaced under warranty. Last month I went on another road trip and it happened again momentarily but hasn't happened again since.
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11-14-2012, 01:56 PM | #6 | |
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The 35i and 35is do have an oil cooler these days but it doesn't fully resolve the issue. My car got up to 280F over the weekend in 50F ambient temperatures and there was some noticeable power reduction (as expected per the post I quoted earlier) |
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11-19-2012, 12:29 AM | #7 |
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2012 35is and >1,200 miles driving on our ED. A good 120 minutes in the 125-160ish range (mph) at the end if it. Never limped it. Then ESS tuned and two days of very spirited driving with the in-law's driving their M roadster and no limp for us.
I did track my N55 auto an limped it 3 laps into manually shifting, but no limp for the first 4 runs in AT sport mode. I'm very surprised you could limp you 35is on public streets without wrecking it, causing a wreck, or getting arrested.
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'15 3500 HD Dually '13 C4S Last edited by wdlfbio; 11-19-2012 at 10:05 AM.. |
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11-19-2012, 09:10 AM | #8 |
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11-20-2012, 12:47 PM | #9 | |
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Some public roads in the middle of nowhere have great sight lines, run off and no one around for miles so it also wouldn't be a huge surprise that a sporty car owner drives those roads similar to how they would drive at a track |
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11-21-2012, 02:44 PM | #10 | ||
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Your last point is valid and I agree, I'd be looking at some cause other than overheating the oil cooling system.
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11-21-2012, 04:06 PM | #11 |
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35i doesn't require illegal driving to get into power reduction temperatures....
I've gotten it to 280F accelerating full throttle from corner exit to speed limit repeatedly. I think temperatures should be rock solid at operating temperature regardless of the usage and this is definitely NOT the case in the Z4 |
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11-21-2012, 08:27 PM | #12 | |
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Well to be honest, we were not out on public roads, we were out at the local road course tracking the 35is. We have done this a few times and never had any issues. The 35is actually does really well on a track. We usually run 5 (2 drivers, each with 5 15 minute session back to back) 40 minutes rounds, and it is normally much warmer outside then it was the day we ended up in limp mode. I am going to put the limp mode problem being caused by the super dirty track and us over working the traction control. My father was able to make it through his 15 minute session and I was never able to make it past 5 minutes in on either of my sessions. The HPFP was changed out already due to a load noise, and have had any other issues since. Jim Last edited by jimi900; 11-21-2012 at 08:33 PM.. |
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11-26-2012, 11:27 AM | #13 |
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Jim, are you using sport + dsc off mode and DCT in manual mode?
I found that the electronics intervene in comfort and even sport without flashing the warning light (noticeable from less rotation / power on exit) and the gearshifts are much better What tires are you using? I enjoy weekend driving in my 35i a great deal as well other than the cooling. Great to see others really enjoying weekends in the car. |
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11-27-2012, 07:38 AM | #14 |
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Is it possible to combine sport mode and dsc off with the 2012/2013 models? Did they change something here? With mine there is no way to combine dsc completely off with "sports" or "sports +" steering/suspension/throttle response/DCT automatic mode.
Last edited by Asbjorn; 11-27-2012 at 07:49 AM.. |
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11-27-2012, 11:13 AM | #15 | |
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I should just refer to it as sports+ in the future to avoid confusion. |
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11-27-2012, 09:04 PM | #16 | |
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And yes I believe you are right. Probably sport+ gives you the best car for fast laptimes as it not only doesn't cut power too aggressively, but also helps to brake individual wheels to kill excessive under/oversteer. At least I do not think you can review the Z4 on the track only by driving it with DSC off (as most do). DSC off is only helpful if you want to balance the car on oversteer for fun. Here I had it in sport+, and because I knew DSC was on, I felt like just flooring it from a rolling start into a 90 degree turn: http://v.youku.com/v_show/id_XNDgxMDEyNzMy.html password: "4". I was very surprised of how much oversteer was allowed before individual brakes were applied by the "sport+" DSC. It is an example of how much slip sport+ actually allows on a dry surface. On the video you can hear how the power is cut slighty while the dsc is applying the brakes. This, until eventually the (slow and very surprised) driver chickened out and applied the brakes himself. Ok, sorry, back to topic... |
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