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M2 Technical Topics > N55 Engine / Drivetrain / Exhaust / Bolt-ons / Tuning > Rough idle in sports+

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      02-09-2017, 07:51 PM   #1
adisz
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After installing a vrsp downpipe I have noticed a rough idle when the car is in sport plus mode.
The revs stay put on the tach but there is a pulse in the idle.
I had a shop look at it and everything was installed correct, no leaks and o2 sensors are fine. Anyone else experiencing this? Only mod is the downpipe.
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      02-09-2017, 09:40 PM   #2
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      02-09-2017, 09:41 PM   #3
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Got a video ?
I'll post one tomorrow.
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      02-09-2017, 10:41 PM   #4
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Yup experiencing the same
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      02-10-2017, 07:42 AM   #5
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Comfort and sport are fine?
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      02-10-2017, 08:04 AM   #6
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Comfort is fine, sport I didn't check. I'll record a video soon.
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      02-10-2017, 03:38 PM   #7
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Yup experiencing the same
Does that not worry you?
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      02-10-2017, 08:33 PM   #8
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https://flic.kr/p/S23MoF

This is in sport plus. Also occurs in comfort it's just muffled.
I will install dinan sport tuner tomorrow and if it doesn't change going back to stock.
In the mean time if anyone can help out DM me or post here.
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      02-11-2017, 05:48 PM   #9
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I had this as well when I had my downpipe installed, I just didn't think much of it because I was untuned with the catless downpipe in, but I have no idea if it has done any damage that will present in the future
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      02-11-2017, 05:54 PM   #10
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Originally Posted by d0scas View Post
I had this as well when I had my downpipe installed, I just didn't think much of it because I was untuned with the catless downpipe in, but I have no idea if it has done any damage that will present in the future
I'm assuming you are now tuned
and it idles normal?
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      02-11-2017, 06:14 PM   #11
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Quote:
Originally Posted by adisz View Post
I'm assuming you are now tuned
and it idles normal?
I am tuned now but I just have a stage 1 flash on stock car I haven't put the downpipe back in after service
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      06-23-2017, 03:30 PM   #12
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I have the same thing with no performance mods. Just got it back from the dealer and they said it's normal for the N55. Funny thing it started around 10K Kms and my previous 335 (N55) didn't have that problem. When it was at the dealers they called and asked it I had a tune in the car???? Also it does it in all modes, just more pronounced in Sport +
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      06-24-2017, 02:59 AM   #13
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Quote:
Originally Posted by Deutsches Blut View Post
I have the same thing with no performance mods. Just got it back from the dealer and they said it's normal for the N55. Funny thing it started around 10K Kms and my previous 335 (N55) didn't have that problem. When it was at the dealers they called and asked it I had a tune in the car???? Also it does it in all modes, just more pronounced in Sport +
Now that I have my stock downpipe it idles normal for the most part. I slightly hear a lopey idle once in a blue. I had many people tell me the n55 doesn't idle the best so I guess it a normal thing on some engines. Otherwise car runs perfect.
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      06-24-2017, 04:43 AM   #14
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Quote:
Originally Posted by adisz View Post
Quote:
Originally Posted by Deutsches Blut View Post
I have the same thing with no performance mods. Just got it back from the dealer and they said it's normal for the N55. Funny thing it started around 10K Kms and my previous 335 (N55) didn't have that problem. When it was at the dealers they called and asked it I had a tune in the car???? Also it does it in all modes, just more pronounced in Sport +
Now that I have my stock downpipe it idles normal for the most part. I slightly hear a lopey idle once in a blue. I had many people tell me the n55 doesn't idle the best so I guess it a normal thing on some engines. Otherwise car runs perfect.
Thanks for the response. I will be adding a sport cat next summer so we shall see what that does to the sound. I presume it will amplify the inconsistency of the idle.
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      06-24-2017, 01:33 PM   #15
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I removed that downpipe as that was an issue and other slight drivability issues. Overall the car didn't feel right. FabSpeed catted DP now, I have no issues and no stink!
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      06-26-2017, 12:47 PM   #16
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I'm catless and tuned still have the rough idle, and the tach isn't moving. Is that bad?
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      08-30-2019, 03:51 PM   #17
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Hey guys, since it's been 2 years since this post was active. Has any of you experienced any fixes or further issues?

I just got myself a 08/2017 M2 and installed a catless downpipe, intercooler and chargepipe. Car is running standard ECU as of now but I'm facing exactly the same issue.

Tacho doesn't move, yet a very noticible change in sound on idle... Car runs smooth for 2 sec then gets louder for 1 sec and so on...

A lot of friends with similar setups on their M2's don't get this... Which is the worrying part for me and makes me think there's something wrong with mine...

I was planning on tuning and further modding the car but now I'm afraid as the car still has 1 year of warranty and don't want to permanently void this just as the engine starts acting weird...

I'd be really appreciative of any help or possible causes or ways to resolve this.
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      03-28-2020, 06:26 PM   #18
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Very curious as to whether anybody has identified a fix for this idle issue after catless DP install even when tuned. I suffer the same.
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      03-28-2020, 10:50 PM   #19
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It's not an issue. It's how the N55 idles. It's just more audibly prominent with an aftermarket downpipe since they're more free flowing and doesn't muffle the sounds as much
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      03-29-2020, 08:11 AM   #20
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Sounds normal to me.
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      07-31-2021, 07:51 AM   #21
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I’ve just changed my downpipe to Active Autowerkz Hiflow DP today and I also noticed this too. If I rev to say 2-3k and let go it’ll drop to normal rpm and gets what I can best described as a hiccup.

This is supposedly normal? I don’t recall it doing that before. I’m on BM3 and I’ve just recently up’d that to Stage 2-93 octane and that didn’t do a thing in this aspects.
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