N54 Rough idle

mihneagtt

New Member
Oct 31, 2021
3
0
0
Hi guys!
I recently bought an 07 335i and I have a problem with it. The idle is kinda rough sometimes and by rough I mean it has some moments when it "shakes" as if the cylinders were out of sync or something. The duration of this "shake" is very short but it repeats over and over randomly. I feel like it's worse at cold starts, but i can feel it even after it has been warmed up, just not as violent. Also, under light throttle between 1.5-2.3k rpm it doesn't feel smooth at all, it's like i'm constantly varying the throttle input even though my foot is steady.
Mods:
JB4 pump bef on 95RON (91 octane)
downpipes
dci's
I recorded some logs:
Cold start
https://datazap.me/u/mihneagtt/cold-start?log=0&data=1-4
Light throttle
https://datazap.me/u/mihneagtt/light-throttle-cold-engine...
WOT on map1
https://datazap.me/u/mihneagtt/wot-map1-jb4-bef?log=0...
The car doesn't have any codes ATM, did have some regarding the vanos solenoids which would also throw the car in limp, i cleaned them and no more codes. Also had a 29E0, but i deleted it and it didn't come back yet. The car also smokes randomly, i have no idea why.
Sorry for the long post, but i've tried to supply as much information as i could. Thank you very much !
 

mihneagtt

New Member
Oct 31, 2021
3
0
0
Check your injectors. Maybe one or two is leaking and o2 sensor voltages are easy to check with ista or inpa. I had rough idle and cold starts and the reason was injectors.
Thank you ! How can i check if the injectors are leaking besides removing the spark plug to see if it's wet?
 

Krampus

Private
Aug 8, 2020
38
19
0
Maybe removing plugs is the easiest way to check leaking injectors. There are a few videos on Youtube as an example, but it’s easier to check the plugs. I had two darkened plugs and the others were of normal color with E85 use. I didn’t remember to smell the darkened plugs when I replaced the ignition coils (B58) and plugs (NGK 94201). Shortly after that I changed the injectors so the idle became smooth.
 

mihneagtt

New Member
Oct 31, 2021
3
0
0
Maybe removing plugs is the easiest way to check leaking injectors. There are a few videos on Youtube as an example, but it’s easier to check the plugs. I had two darkened plugs and the others were of normal color with E85 use. I didn’t remember to smell the darkened plugs when I replaced the ignition coils (B58) and plugs (NGK 94201). Shortly after that I changed the injectors so the idle became smooth.
Thank you very much for your answer! How are the logs looking like ? Not regarding the rough idle, but in general. I'm new to the n54 platform and I'm struggling a bit to read the logs, but from the little knowledge that i've gathered it seems like the hpfp is healthy and the turbos as well? I also think it's pulling a bit of timing ?