E90 N55 PS2 wedge tuned, oscillating idle

[E90Tech]

Hey guys, new member here. Currently I am running an E90 335 x drive
I am running pure stage two turbo
FBO, 450 welbro, Arc EKP
Currently tuned by wedge performace 93 pump gas

The car is meticulously maintained. I am a certified BMW tech here in Canada at the dealer.

Unfortunately, I don’t know everything and when it comes to tuning, I’m no expert. I enjoy the set up that I am currently running as a daily but I am running into an idle surging issue when turning left in the Tim Hortons drive-through with stop and go

As well, I installed the arc terminating EKP
And reset adaptations and programmed with protool

I noticed there is a slight surging/oscillating idle

I’m not sure if it’s a lazy O2 sensor or if it’s my tune, but I’m pretty sure it did the surging when it was factory

It’s been happening for a while and I don’t really drive the car but lately it’s driving me nuts.

I’ve uploaded datazap for the oscillating idol after EKP modular replacement.

I was reading other members post and I seen some other people running into issues with wedge tuning. I heard these guys are one of the best, but I definitely am second-guessing the tune only from what I read online.

Any input from the wizards would be fantastic!

datazap.me | JamieLynch | Idle surge

datazap.me

 

[Richm240xi]

What year is your e90? And a lot of us including myself have the weird idle issue, I think it’s just a thing with these n55s, I had it as well even before I was tuned although less noticeable then. The way I was able to make it less noticeable was by raising the idle in MHD and turning off the decoupling with XHP ( I have the 6 speed auto) it’s still there but much less noticeable now. My tuner David Shoup said he believes it’s a mechanical issue, so I’m supposed to try new spark plugs but I’m doubtful since the ones I have on now have only about 10k miles. I have the new plugs just haven’t gotten around to installing them yet but will report back if it makes a difference. Would like to keep this thread going with any other n55 owners that have the same issue.

 

[E90Tech]

Mine is 2011, I have oem BMW NGK plugs installed (N55 plugs)
If I’m in the drive thru and basically touch the gas and then stop to move just a bit forward it will almost stall it will rev up and down.
IF I put the car into neutral it will stop doing it and immediately and then start doing it once it’s in drive.

I am currently running xhp stage 3 as well and have decoupling off. I believe it may be mechanical. I’m gong to run a log and post it for the more extreme surging issue.

I’ve also have replaced valvetronic servo motor and shaft for unrelated issues

My thoughts are at this time a binding transfer case issue, lazy o2 sensor (maybe)
Vanos issue of some sort either the solenoid or actuator. Or it’s an internal transmission issue causing some type of load that really messes with the DME values.

Steering input has a factor for the really bad surging.

My DME is also at the latest I level that apparently a software update was suppose to fix an issue like this.

 

[Richm240xi]

I also have a 2011. As far as maintenance goes, you've done more then me, so i guess i can cross all those things off my list as far as where to look at. I currently have the nexys b58 kit with the oem bosch n55 plugs, gonna be swapping them out for the oem ngk b58 plugs to see if that helps. As far as searching in forums, it looks like no one has ever gotten a definitive fix

 

[wheela]

Your rpm oscillation seems to correlate to lamda and STFT% oscillating. Not sure why they're doing that? I saw that same correlation in a different guy's log who had the same issue. Not to recommend blindly throwing parts at a problem, but I wonder if an O2 is going bad?

I also noticed your rail pressure takes a big dip, and doesn't seem super consistent. Not sure if that would be an issue with your hpfp or your rail pressure sensor? If something is up with those, it could explain the fueling/lamda oscillation.

I guess in order of suspicion, I'd go:
1. Rail pressure sensor (because it's cheap)
2. HPFP
3. Upstream O2 sensor

Just my suspicion, I could be completely wrong.

 

[Richm240xi]

Your rpm oscillation seems to correlate to lamda and STFT% oscillating. Not sure why they're doing that? I saw that same correlation in a different guy's log who had the same issue. Not to recommend blindly throwing parts at a problem, but I wonder if an O2 is going bad?

I also noticed your rail pressure takes a big dip, and doesn't seem super consistent. Not sure if that would be an issue with your hpfp or your rail pressure sensor? If something is up with those, it could explain the fueling/lamda oscillation.

I guess in order of suspicion, I'd go:
1. Rail pressure sensor (because it's cheap)
2. HPFP
3. Upstream O2 sensor

Just my suspicion, I could be completely wrong.

Hey wheela I’m a noob when it comes to reading these things, how does mine look? Thank you

datazap.me | Richm240xi | Log 1724874916

datazap.me

 

[wheela]

Hey wheela I’m a noob when it comes to reading these things, how does mine look? Thank you

datazap.me | Richm240xi | Log 1724874916

datazap.me

You have that same stft% and lambda oscillation that correlates to rpm oscillation, but I don't know why or know how normal it is. My stft% oscillates at idle too, but my lambda and rpm don't. Also, my rail pressure is pretty consistent around 1010- 1020 ish psi.

I haven't looked much at idle logs since I don't have any idle issues, hopefully somebody else can chime in.