[Icey]

So I’m running stage 2+ (93 octane tune) FBO on my 2015 435i 8 speed stage 3 XHP
yesterday I went to go fill up on 93 octane gas and later in the day I’m leaving my neighborhood come to a complete stop, and my cars rpm drop and the cars about to stall but it doesn’t after that the whole day the car was fine, fast forward to today I’m driving maybe 10 min come to a complete stop car stalls start it up drives completely fine the whole day, any ideas ? LPFP? Bad fuel? Fuel rail pressure seems to be hitting 1300 on idle and over 2k on while driving

[thejeremyman9]

No codes in kinda weird if it stalled. Log WOT 4th gear pull and make sure fuel pressure holds. If the stalling is recurring/repeatable, try and log or at least monitor fuel pressure live and see if the car stalls because it loses fuel pressure.

If it only happens after getting gas there is the fuel tank vent valve thing but i am not sure if that causes these exact issues

[Icey]

Originally Posted by thejeremyman9

No codes in kinda weird if it stalled. Log WOT 4th gear pull and make sure fuel pressure holds. If the stalling is recurring/repeatable, try and log or at least monitor fuel pressure live and see if the car stalls because it loses fuel pressure.

If it only happens after getting gas there is the fuel tank vent valve thing but i am not sure if that causes these exact issues

Fuel pressure holds perfectly fine on 4th gear WOT, and did a run of 1-4th WOT no dips in fuel pressure

[BeastMode335i]

Originally Posted by Icey

Fuel pressure holds perfectly fine on 4th gear WOT, and did a run of 1-4th WOT no dips in fuel pressure

Did you fix this? I'm having the same issue all of a sudden.

[Zprado]

Originally Posted by Icey

So I’m running stage 2+ (93 octane tune) FBO on my 2015 435i 8 speed stage 3 XHP
yesterday I went to go fill up on 93 octane gas and later in the day I’m leaving my neighborhood come to a complete stop, and my cars rpm drop and the cars about to stall but it doesn’t after that the whole day the car was fine, fast forward to today I’m driving maybe 10 min come to a complete stop car stalls start it up drives completely fine the whole day, any ideas ? LPFP? Bad fuel? Fuel rail pressure seems to be hitting 1300 on idle and over 2k on while driving

Update on your issue ?

[fast135i91]

Hello,

I am having the same issue. Same code 21a023. Same engine stall once I approach a red light and idle for a few seconds. Auto start stop disabled.

My 2015 335i started randomly stalling at idle after driving for at least 15-20 minutes. For instance, I drive for 15-20 minutes or more, and then stop at a red light, and after 10-15 seconds of idling, the car lightly stalls and kicks into Neutral gear position. Auto start/stop is off. And computer threw a few codes but did not set CEL (see pic). (Lightly stalls meaning no rough jerk with stall).

Also interesting, is that after it lightly stalls, it starts right back up no hesitation. No limp mode. No half engine light. No other symptoms. Full power is available. It stalled with BM3 OTS stage 1 ACN map. And it also stalls with stock map. Engine oil full. Gas above 1/2 tank, Chevron 91octane. No coolant leaks. No oil leaks. No overheating. No unusual noises.

Checking sensor data, alternator output is 25+ amps. Battery voltage is 14.5-14.7v while running. Battery state of charge is 98%. Again, no misfire nor driveability issues. This just started happening, and since it is my daily, I’d like to fix it as soon as possible. I was initially going to wait for a CEL to turn on if the problem got more consistent or worse.

128k fantastic miles. Stock intake. Catless DP.

Checked engine air filter and it’s dry and clean.
Checked around engine bay and no chewed wires or anything.

I was thinking it could be a EKPM3 or fuel pressure sensor since those both could possibly be faulty without setting a CEL. Just a guess.

Any thoughts?

Thanks in advance.

[vlmki]

I got the same problem with my -15 435iX. Car dies or revs drop to ~400rpm for a second if it's idling with brake pedal depressed and D gear applied.
Sometimes it idles fine for minutes, sometimes it dies after few seconds.

Last flash for dme/egs was about a month ago. Refilled full few weeks ago, drove for 1/2 tank before this fault appeared.

My only fault code on DME is 21A023 and EGS doesn't have any codes.

I did a lot of logs on idle with MHD and out of nowhere my "Fuel mass flow rate" drops from ~26 to ~15 and "Timing Cyl. 1-6" from -1 to -23, then ~ hundred milliseconds later revs drop or car completely shuts down. Before this drop on fuel mass and timing all the values are quite smooth.
Few times car shifted from D1 to D6 while standing still, MHD log shows RPM 0 before 6th gear comes in but if the log shows that the 6th gear is in use already (not that it's about to shift), I wonder if the request to shift 6th gear is the reason fuel mass and timing collapse.
WOT logs look just like before this fault and other than idle on D gear applied, car runs absolutely fine.

Ss of log attached:
Purple=Fuel mass flow rate
Green=RPM
Red=Timing Cyl. 1 (not timing correction but actual timing, corrections are 0 all the time at idle on every cylinder. On other 5 cylinders timing goes also down to -23 at the same time)

Mods:
-catless dp
-do88 intercooler
-CTS charge pipe
-MHD stage 2+ E20
-XHP Stage 3

Yesterday I flashed to MHD stage 0, still the same problem.
Today I filled almost empty tank with 93oct, uninstalled MHD and XHP completely, not stage 0 but complete uninstall for mhd and xhp, back to stock. Idled the car for ~30min against brake on D gear and idle was smooth all the time. No fault codes, no stalling, revs not dropping etc, all good!

However engine was warm already when I uninstalled and this stalling problem was worse with cold(ish) engine but before this uninstall even with warm engine it would stall within 10min of idling.
Will see tomorrow how the car runs after coldstart.

If car works with mhd&xhp uninstalled but problem comes back after installing, I will try to idle the car on M1 gear. Wondering if this whole thing is some kind of a bug on MHD/XHP, something like EGS telling to DME "I will shift to 6th now while the car is standing still" and then DME pulls fuel&timing. Who knows?

E: added log with shifting to 6th gear right after timing, fuel mass and rpm collapsing

E2: With mhd&xhp I had brap&ignition cut on shifting enabled, no burble. I reviewed my wot logs again and found that ignition is retarded by approx. 20 degrees around gear shift and also fuel mass flow comes down by a lot. Somehow leaning more towards that for some reason my car was trying to shift at idle and that messed up the ignition timing, fuel mass and revs. Also every log where car shuts down on idle and I'm logging the gear, it shows 6th for ~100ms right where it shuts down, then the gear goes to 0 (neutral).

[vlmki]

Update:
-changing between MHD stage 0, stage 2+ and complete MHD uninstall seems to have no effect with the stalling

-Uninstalling XHP solved the problem, car idles smooth at stop on D gear with stock transmission firmware

-Just before dropping the ignition timing, fuel mass flow and shifting to 6th, torque limiter 1048576 (GS_PERM torque limit sent from transmission over CAN) shows in MHD log.
With XHP installed I had "torque limits per gear" at 1200nm for every gear as I just didn't want to limit the torque with ~440hp xDrive car.
Now reinstalled XHP but this time with "torque limits per gear" at 750nm for every gear, my car has maybe 600-700nm so it's not hitting these limits. Now the problem is gone, idles completely smooth again.
I messaged XHP's support about this, let's see what they say.

[Icey]

Update, turned out to be my tranny tune, I had just flashed new settings, and I guess the car didn’t like them so it’d just stall, reflashed the old settings I had, hasn’t had the issue in months (knock on wood)