[Vania335i]

Hi guys... I'm sure there are tons of posts about rough idle issues... but i couldn't find one similar to my issue
Car is an 08 335i MT... FBO. running MHD 2+ tune on 98 RON... index 12 injectors installed and coded 3 weeks ago... new 1 stage colder plugs new coils... wallnut blasted a few months ago... new oil seals all around... new turbo VTT stage 1... K&N OEM style filter..new engine and transmission mounts... 405 whp
Problem: the car has a slightly rough idle... it had this problem since day 1. Which i assumed was because of poor maintenance or the lack there of from the previous owner or due to the fact that the car was running index 7 injectors when i got it..
The car has no codes whatsoever... no drivability issues... no hesitation...
But at idle you can feel every few seconds like every revolution or so the engine feels like it's skipping ... misfire is the closest term i can use... but its not a misfire cause the RPM does not fluctuate... there is no stutter... no smoke... no abnormal fuel consumption... no oil consumption... when i scan the car for smooth values... all 6 cylinders are smooth...
any ideas?? Is this normal or should i dig deeper

Thanks

[Ruster82]

Hi I would be interested to hear peoples opinions on this too because mine does what sounds exactly the same, feels like the engine skips a beat every now and again only on tick over but the revs never dip/rise and the car pulls solid on acceleration with no issues.

Mine is almost stock, all it has is DCI and a remap, I was assuming the slight stumble on idle was a characteristic of the car and wasn't to concerned with looking into it so any info people have on it would be great.

[E92William]

I would like to see a live data fuel trim reading of this thing at idle. My 335 used to do that but honestly I was tired enough of fixing shit on it that I had let it be lol, good enough for index 2s. Got a lot better running some chevron techron

[Ruster82]

I am new to using INPA but if someone can tell me how to do live readings to post on here I can try and get it

[BM3Rrrr]

Need to do an idle log, it will help diagnose but it sounds like it something on the fueling side.
Could be injector or fuel pressure related

[Vania335i]

Data logging using MHD?

[BM3Rrrr]

Originally Posted by Vania335i

Data logging using MHD?

Yes

[Ruster82]

Here are links to INPA videos which is the best I can show as I don't have MHD. Sorry this took me so long to get round to.

Rough running idle, cylinders six hits into the red slightly every now and again:

https://streamable.com/o8na3i

Rough running with revs, all stay within the green:

https://streamable.com/m8ddoc

Lambda readings bank 2 after cat takes longer to recover after car is reved:

https://streamable.com/a0vpwm

Vanos, top right never moves off of 8.8 while the others all change when reved. is this right?:

https://streamable.com/kpbnap


Hopefully the links work and the info is useful to help solve the issue of stumbling idle.

[longm1985]

Originally Posted by Ruster82

Hi I would be interested to hear peoples opinions on this too because mine does what sounds exactly the same, feels like the engine skips a beat every now and again only on tick over but the revs never dip/rise and the car pulls solid on acceleration with no issues.

Mine is almost stock, all it has is DCI and a remap, I was assuming the slight stumble on idle was a characteristic of the car and wasn't to concerned with looking into it so any info people have on it would be great.

Mine does exactly this too. Thanks for posting your INPA data, by the way. That might be extremely helpful. I'm aware you're dealing with an N54/55 and I'm dealing with an N52, but I imagine the cause will be similar.

I'm digging this up from the dead in case anyone else has some thoughts on the topic.