08-14-2018, 09:55 AM | #1 |
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Cold start rpm drop
Soon after I started my car, the rpms dropped more then usually. I thought it was gonna stall but they climbed back up quickly. Has this ever happened to anyone else ? Is it a problem?
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08-14-2018, 10:02 AM | #2 |
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Me and some other m2 drivers had this issue this summer driving in the dolomites in italy. I guess it was bad gas. Engine almost stalled.
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09-25-2019, 11:27 AM | #3 |
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Yea my car is having a similar issue that I haven't noticed before. On cold start, RPMs start at ~1000, drop down to 500-600 for a second and the engine sounds like it's almost going to stall, and then it shoots up to 2000 real quick. I presume the latter part is normal for the cold start mechanism but the 500-600 bit seems weird.
I just moved to Colorado where the highest rated gas I can find is 91, but that alone wouldn't be bad enough to cause this, right? Can anyone comment on what the cold start mechanism normally is and if mine is indeed abnormal? |
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09-25-2019, 08:41 PM | #4 | |
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09-26-2019, 04:03 PM | #5 |
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Same here only sometimes, I always run 93 and octane booster. so gas is not the issue for me, I do have a bm3 tune, intake, ic, catless dp. Again, it never stalls and only sometimes does the weird cold start. I have not really worried about it as it clears up within seconds and i assume it is just related to the tune .
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04-16-2023, 01:30 AM | #6 |
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Hey. I’ve got a 2018 F87 M2, and I’m getting the same issue. Idles low, stalls sometimes. But it runs fine when driving. I did the MAF trick where I unplugged it for 10m and it worked for a day, car had no issues the whole day. I’m thinking I need to replace the MAF sensor. Has anyone had this issue and had luck when replacing the MAF sensor?
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04-16-2023, 02:18 AM | #7 | |
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04-16-2023, 04:53 AM | #8 | |
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Sometimes intakes can be the cause of these issues, because it changes the way the maf sensor reads air flow. I think the root cause of this can be due to the maf sensor housing being poorly designed, so not only does it make the sensor read air flow inaccurately, but it could also not seal the maf sensor area correctly and allow air to leak by.
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04-16-2023, 02:34 PM | #10 |
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No this issue shouldn't be occuring with the cts intake. I'm not really sure why it's happening to you.
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04-16-2023, 03:01 PM | #12 |
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Yes I know, that's why I asked about your intake. Maybe you should try cleaning your maf sensor with crc maf cleaner.
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04-16-2023, 04:40 PM | #14 |
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you could always replace the sensor if you wanted, but I'm not sure the sensor could be damage by sitting in the intake.
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04-16-2023, 04:49 PM | #15 |
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But the how did the MAF sensor trick work? I disconnected and let it run for 10m and then plugged it back and all day it ran like a gem. So that shows me it was the sensor
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04-16-2023, 05:12 PM | #16 |
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I have a code P0133 which is slow response. I’m not getting any codes related to intake or MAF, however it is stalling / running bad on cold starts. So it has to be the MAF unless I’m mistaken
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04-16-2023, 05:36 PM | #17 | ||
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So let me ask you, does this only happen on cold starts? Or does it happen on warm starts too? Otherwise if you want you can just try a new maf sensor, it is your choice. Personally I would try to clean it first. Quote:
Wait, so does it only occur on cold starts?
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04-16-2023, 09:08 PM | #18 |
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So it’s sort of random. Most of the time it was bad on cold starts. RPMs would jump, then drop. Then sometimes it even stalled. Othertime times it ran fine then sometimes woukd drop RPMs, and stall in park.
This is the thing with the MAF. I agree it could be it. But then at the same time why didn’t it happen before, and only started occurring when the downpipe was installed. Hence brings me to my conclusion I think. I currently have a CEL from “Slow Response” from O2 sensor. I cleared it multiple times and it came back about two hours later each time. So I’m thinking the error was always there, even at first when it didn’t throw a CEL, but that was the reason my car would run bad. And now the issue is finally recognized after the car getting used to the downpipe. So now I think it’s caused from the slow response from O2 sensor because that can easily have symptoms of stalling car and weird idles etc. Make sense? |
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04-17-2023, 04:17 AM | #19 |
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How long has this issue been present? I chased down a similar one for a month, then went away and oddly came back the same time the next year. Then I realized it was pretty close to the switch in summer-grade gasoline, which is occurring around now in certain places. If this has only happened very recently, especially on one tank of gas, try a different gas station.
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04-28-2023, 11:10 AM | #20 |
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My first start up after storing the car over winter had this exact issue. RPM dropped to 400/500 and almost stalled. I use 91 octane with fuel stabilizer storing the car over winter.
I drove the car almost empty and filled it up with fresh 94. Haven't happened again. |
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04-28-2023, 01:56 PM | #21 |
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What 94 do you use? Petro Canada is notorious for having horrible winter gas that performs even worse than shell 91.
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04-28-2023, 03:16 PM | #22 |
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I use Esso. I only run 94 in the summer when I'm driving the car since I think most of them have ethanol. When I stored my car I used co-op 91 since I heard they don't have ethanol in the 91.
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