07-11-2016, 12:39 AM | #1 |
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1.5 years old, 20k km M235i: my first glitch
Before I turn to my BMW Stealer, I'd like to seek your advise guys on this:
- when I fire up my M235i after a day (or couple of days) in the garage and immediately engage Reverse to rear back from it, I can feel something that never happened before: the rpm (quite high - as usual with totally cold engine) go crazy fluctuating, and the car's movement is jerky and uneven. But once I put it to Drive and pull away, everything is normal again - so it only happens on the very short distance of some 15 meters, but still feels not normal... I'm not even sure whether it's the uneven rpm of the cold engine, or something is going south with my 8AT torque converter (also when the entire tranny is cold right after firing the car up after a longer time in the garage)... I didn't check if the same would happen in the movement forward, as I hate to leave my car outside the garage so that my first several meters in the morning would be in D and not R - but I'm positive that it's only durign this very first backwards movement: when I stop the car after just several meters of driving it forward and engage R again - even though the engine and tranny are still pretty cold - all is normal. Have anyone had a similar experience? What the reason could be for this behavior? Opinions welcome! TIA Piotr
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07-11-2016, 03:20 AM | #2 |
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Can you reverse into the garage so when you're traveling down the driveway in the morning you're already in D?
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07-11-2016, 03:40 AM | #3 |
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Yep - will do that next time
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07-11-2016, 07:07 AM | #4 |
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Yes, I've had the same thing. On cold starts, putting the car in R immediately, the revs jump around and sometimes the engine stalls. BMW did some updates and it didn't stall again, but revs still not perfect.
I've noticed it not happening recently since always using 98RON fuel instead of 95RON though.
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07-11-2016, 08:08 AM | #5 |
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Do you guys move the car during the cold start ? I always wait for the drop of the rpm at 600-700 rpm before putting the car on D or R. I've done that with all my cars Mazdaspeed3, 335i N54, ...
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07-11-2016, 08:55 AM | #6 |
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I always wait a few seconds to let it even out. Only takes 5-10 sec.
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07-11-2016, 06:38 PM | #7 |
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My car will do the same thing unless I wait for it to warm up a bit. It is doing it even in 60 degree weather.
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07-11-2016, 06:59 PM | #8 |
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MT here, and I noticed sometimes upon start up when I take my foot off of the clutch pedal that the RPMs start to jump a bit, almost as if the car was struggling to get fuel.
Only happens on cold starts though. And only happens as I release the clutch pedal immediately after starting.
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07-12-2016, 10:20 AM | #9 |
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Thanks for all the answers. Nothing explains my problem as it wasn't there until recently. And yes - the engine pulls as usual afterwards... I'm going to do all the suggested tests tomorrow, and will report here.
Piotr
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07-15-2016, 04:51 PM | #10 |
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Why not let your car warm up at least 20 secs or so after starting until the RPM automatically lower before putting in gear? Seems like a nice thing to do to your engine no matter what kind of car you drive.
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07-15-2016, 06:22 PM | #11 |
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Let the engine gather itself. You're not practicing ideal warm up procedure doing what you're doing. Let the revs drop after the cold-cold start and you should be able to drive away without a hitch.
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07-15-2016, 07:58 PM | #12 | |
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Absolutely no issues with 10 to 12 seconds after start, drop off of high idle and down to 800 rpm, everything is predictable. In colder weather (40 and below) I will let it drop down to a normal idle before rolling off. |
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07-16-2016, 12:45 AM | #13 |
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I promised to keep you updated on this, so here is the current status:
The jerkiness while backing off my garage immediately after cold starting the engine has disappeared as quickly and suddenly as it had appeared a couple of weeks ago. I went do my BMW dealer to diagnose the car for any hidden errors and they found nothing! Nevertheless, since my car was already on the bench, they updated the software to the latest version available - here is what I have now, according to the print-out they handed me over (someone please tell me what the three entries mean): 1. iLevel.iLevelBackuP: F020-15-03-502 (I guess it's the previous version?) 2. I-Level HO: F020-16-07-502 (I take it for the current version after programming) 3. I-Level Factory: F020-15-03-502 (as the numbers 15-03, which I take for March 2015, are the here and in item 1 above - I guess it's the software level/version my car had left the Factory with; indeed it's a March 2015 build) 4. New I-Level available: No So I guess my current software is as per item 2 (F020-16-07-502), and there is no newer version available. I guess I need to download a newer version of Psdzdata for E-sys coding I have on my PC, as I can see the "15_03_502" suffix in the main series names (which corresponds to my Factory software version which has been over-written with "16-07-502" now... Anyway - I must use the car for some more time to recognize the changes in engine behavior (if any) the new software introduce; my first impression is the slight and sporadic throttle response delays I've had before are now gone - but it's definitely too early to be positive about it. As to my original problem this thread is about, I think - given there have been no error codes found, and it never happened again - the reasons could be one of the 2 following facts, or a combination of them: - while normally using RON 98 fuel, there had been a single fill-up of RON 95 just before the jerkiness started (and my SA at BMW dealership said something about the controllers needing some time to adjust to RON changes) - while normally I re-fill when the fuel gauge shows no less than 1/4th of the scale, for some reasons I re-filled with RON 98 only when my RON 95 fuel was almost gone (just a few liters remaining, and iDrive showing only some 50 km of range remaining. All in all, the problem is gone - hopefully for good :-) Piotr PS. In spite of all the advise on allowing some 10 seconds or so for the rpm to stabilize right after the cold start, I keep engaging the gear and moving my car immediately (of course in an adequate way - i.e. not revving the engine before the rpm stabilizes). All is good again - no more jerkiness at all. BTW, all of you guys probably noticed that when still cold, the AT8 tranny will do its first upshift (1st to 2nd) at higher rpm than with the engine and gearbox at operating temperatures; therefore - in order to avoid high rpm with totally cold engine - my very first upshift I always do myself using the paddle...
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07-16-2016, 01:09 PM | #14 | |
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07-16-2016, 07:04 PM | #15 |
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07-16-2016, 07:19 PM | #16 | |
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Most manufacturers attempt to do like the above in an effort to warm up the engine faster, with the expense of added engine wear. |
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07-16-2016, 07:41 PM | #17 |
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Engines rev on start to overcome the higher internal friction of various components when the car is cold. The engine needs to build oil pressure as fast as possible. Not much wear unless under load, that is why they stall sometimes when you start and go asap. It's probably one of the worst things you could do to your engine. Emissions are horrible until cars are warmed up and the cats can do there job, engine can run leaner. If you want to go asap, go electric.
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07-16-2016, 09:32 PM | #18 | |
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07-17-2016, 12:42 AM | #19 | ||
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Piotr
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07-17-2016, 08:17 AM | #21 | |
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Why are you preaching engine warm-up when you made this thread specifically stating that you start the engine and immediately throw it into gear and expect it to be cherry? Practice what you preach |
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07-17-2016, 09:00 AM | #22 | |
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Basically a engine wants to get to operating temp as fast as possible to be as efficient as possible, until then not so efficient. Exhaust scrubbing is accomplished via the catlictic converter do not happen until 400-500 degrees, peak scrubbing is around 1200 degrees. Here is a link to an article that may help you. Internal combustion engine cold-start efficiency: A review of the problem, causes and potential solutions Andrew Roberts ,Richard BrooksPhilip Shipway Division of Materials, Mechanics and Structures, University of Nottingham, University Park, United Kingdom Received 29 October 2013. Accepted 1 March 2014. Available online 3 April 2014. http://www.sciencedirect.com/science...96890414001939 Last edited by Pparana; 07-17-2016 at 09:17 AM.. |
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