| 07-01-2020, 02:54 PM | #46 |
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Reviving this thread to say I have catless downpipes and DME stage 2 tune. Stalling on every cold start now. Havent found a solution and both DME and my local shop have explained that its just something to live with on this car. VERY MUCH looking for anyone that happened to solve it as I am not keen on going to stock downpipes...
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| 07-02-2020, 05:29 AM | #47 | |
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| 07-03-2020, 04:51 AM | #48 | |
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| 05-12-2021, 05:41 AM | #49 |
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Did anyone ever find a solution? O2? What did the dealership say? My wife’s car (no mods) just started doing the same thing a few weeks back.
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| 05-25-2021, 06:46 AM | #51 | |
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| 05-25-2021, 12:42 PM | #52 | ||
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Even when i just changed to high flow dps i left the cold start off for a bit. Very smooth start like a avalon lol. Too smooth and quiet. I was afraid of damaging the high flow dp if i had cold start off so I turned it back on recently.. hope mine don't start stalling too. If it ever does first thing i will test is cold start off on the high flow dp. |
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| 06-02-2021, 09:06 AM | #53 | ||
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I bought a new aftermarket exhaust systems from Valvetronic and the issue went away. I didn't code out cold start or any software changes. I have Active Autowerke.
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| 06-02-2021, 07:46 PM | #54 |
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Looks like no one has solution yet.. mine deff getting worse next step is to change coils o2 sensors and mass air flow sensors.. going to bring to dealer for one more try to see if they'll find something before I change everything
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| 06-02-2021, 11:58 PM | #55 |
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To add my experience. I had cracked intake boots. Where the intake boot bolts onto the turbos. There was evidence that they had been cracked for awhile, as there was oil residue around the outside turbo intake housing.
On occasion I had very rough cold start idle ranging from 400-1500 rpms. Since installing catless dp and rk intakes which led to finding the cracked intake boots. Replacing the intake boots. Flashing bm3 st2 no cold start. It starts like dream for 2 months straight. Hopefully this isn't the case for others but worth a check. |
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| 06-03-2021, 09:17 PM | #56 |
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my car constantly throws vent valve hose errors on both sides and has lumpy idle. Replaced hoses. still remains. Found cracked turbo inlet hoses and sealed up. still remains. About to replace MAFs (cleaned them, no change). Car still pulls strong. Stage 1 ECU tune, stock DP. Also changed plugs to colder step. No change. 36k miles
My M6 with the same tune has been flawless for years. This X5M engine is finicky
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| 08-21-2021, 02:38 AM | #58 |
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Is it like this? Trying to solve it for more than a year…
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| 10-02-2021, 05:45 AM | #60 |
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Occams Razor…even if vehicle in question is modded, the simplest solution attempt to remedy problem is Chevron Techron Complete Fuel System Cleaner. One 20 oz can to a fill up and then another back to back treatment. Air /spark/ fuel equals combustion…when I get stupid and use non top tier fuel, the problem usually reads its ugly head…Techron seems to cure it
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| 10-02-2021, 01:29 PM | #61 |
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Tunes are usually the main problem.. if u don't have time or any upgrades u know it's prob mass air sensor or injector.. even with a bad plug it wouldn't give that kind of problem.. my problem was my bm3 tune wasn't set right.. o2 sensors were shut off and cold start was turned off n now running beautiful even tho first start usually has few few seconds of rough idle which I thinks perfectly fine considering there no cats and it's tuned so
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| 10-05-2021, 05:19 AM | #62 | |
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Has anyone discovered what this could be? I'll be digging through the car to see if I spot anything noticeable and report back, but if you've found something I'd love to know |
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| 10-05-2021, 08:30 AM | #63 |
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It's fueling related. I described this in detail in this post:
https://f15.bimmerpost.com/forums/sh....php?t=1858262 |
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| 10-09-2021, 07:04 PM | #64 |
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Update.
I just picked up my car from dealer. They had contacted bmw M division North America for consultation about this problem and they were instructed to replace all MAF sensors, all spark plugs and all injectors. So my dealer did that, and reset all adaptations. I can finally tell you that it fixed the problem. Update.. It still does this… currently talking with bmw of na about this issue. As well as scored cylinder walls which I believe is the main cause I think everyone needs to call and report this issue to bmw na, who knows, maybe they'll take some action  |
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| 10-09-2021, 07:12 PM | #65 |
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As my post says, it's 100% injector related. What the injectors are actually spraying vs what the ecu thinks are the correct offset no longer match. This is particularly trouble at idle on di motors. Cleaning them helps, lower rail pressure helps, but replacing after 50k miles is the best option
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| 02-13-2023, 11:57 AM | #66 |
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I am posting this here for anyone that finds it. I solved my cold start stumble very easily.
2014 XDrive 35i I unplugged the MAF on a cold engine and gave it one complete warm-up and drive cycle with the MAF unplugged (it ran fine and no check engine light came on). Then I plugged the MAF back in and allowed the motor to go back to completely cold before turning it on again. The issue has not returned for 1 month of daily starts. Previously, it was stumbling and running rough on every single cold start for 5 months. I was dreading the injector replacement or taking it back to the dealer for coding. Neither was necessary. I can't explain it, but I saw it posted a couple of other places and it also worked for me. I'm assuming it resets some adaptions. Anyway, hope this helps someone! |
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