[Mircea]

Hi,

Short version: Cold engine drives perfectly fine for about 5-10 minutes then CEL comes up and engine misfires on ONE random cylinder, goes away completely if car is turned off and on again and doesn't come up until next day when the process is repeated.

And the long version, I think it's warranted...

My car is an n53(b30) with all injectors replaced to index11 in Feb2019 by myself (due to rough idle on cold, which fixed it), then remapped to 330i power in Oct2019, and xhp stage 3 on the gearbox somewhere in 2021.
I have a KDCAN cable with INPA (from bimmertools) and can get as much info on this as you need me to (if ISTA is needed I can acquire that too).

The engine recently developed a very strange issue that I don't really know how to diagnose properly.

Steps to reproduce the issue:

1. Leave car to be cold for about a day or so
2. Get in the car, start it, idles absolutely smoothly I could balance a coin on the engine
3. Drive it for about 5-10 minutes
4. CEL comes up and engine feels like it's misfiring, with slight loss of power
5. Pull over, stop the engine for a second or two, restart it
6. Car idles perfectly fine and smooth and drives excellent without any power loss and CEL gone

Sometimes, the CEL goes away while driving, but comes back very soon.


Codes present:

Tests have been done clearing codes each time, so I get a timescale of what's what.

$error locationNr: 11805
$error locationtext: 0x2E1D Zündung, Zylinder 6                                       
Error: 9(10) No.: 11805  0x2E1D Zündung, Zylinder 6                                       
  error type: 2  (4841 ) Brenndauer zu kurz                                                 
  readines Flag: (16 ) Testbedingungen erfüllt                                              
  error status:  (32 ) Fehler momentan nicht vorhanden, nicht OBD-entprellt                 
  MIL - Status:  (48) Fehler verursacht kein Aufleuchten der Warnlampe (MIL)                
class :  11;  frequency: 37;   entry at km: (1.): 166136 km   (2.): 166136 km   (n.): 166224 km 
___________________________________________________________
 
$error locationNr: 10706
$error locationtext: 0x29D2 Verbrennungsaussetzer, Zylinder 6                         
Error: 10(10) No.: 10706 0x29D2 Verbrennungsaussetzer, Zylinder 6                         
  error type: 1  (5514 ) Einspritzung wird abgeschaltet                                     
  readines Flag: (16 ) Testbedingungen erfüllt                                              
  error status:  (32 ) Fehler momentan nicht vorhanden, nicht OBD-entprellt                 
  MIL - Status:  (49) Fehler wuerde das Aufleuchten der Warnlampe (MIL) verursachen         
class :  D6;  frequency: 3;   entry at km: (1.): 166136 km   (2.): 166216 km   (n.): 166216 km

Some additional codes before the ones above (but not always present when issue arises)

$error locationNr: 12548
$error locationtext: 0x3104 Laufunruhe, Schichtladebetrieb                            
Error: 6(10) No.: 12548  0x3104 Laufunruhe, Schichtladebetrieb                            
  error type: 1  (5318 ) Erhöhte Laufunruhe im Schichtbetrieb                               
  readines Flag: (16 ) Testbedingungen erfüllt                                              
  error status:  (33 ) Fehler momentan nicht vorhanden, OBD-entprellt                       
  MIL - Status:  (48) Fehler verursacht kein Aufleuchten der Warnlampe (MIL)                
class :  11;  frequency: 4;   entry at km: (1.): 164912 km   (2.): 164912 km   (n.): 164912 km 
___________________________________________________________
 
$error locationNr: 12506
$error locationtext: 0x30DA Stickoxidsensor, Signal                                   
Error: 7(10) No.: 12506  0x30DA Stickoxidsensor, Signal                                   
  error type: 1  (4786 ) Signal nicht Verfügbar im Start                                    
  readines Flag: (16 ) Testbedingungen erfüllt                                              
  error status:  (33 ) Fehler momentan nicht vorhanden, OBD-entprellt                       
  MIL - Status:  (48) Fehler verursacht kein Aufleuchten der Warnlampe (MIL)                
class :  21;  frequency: 5;   entry at km: (1.): 164960 km   (2.): 164984 km   (n.): 166136 km 
___________________________________________________________
 
$error locationNr: 10988
$error locationtext: 0x2AEC Stickoxidsensor, Eigendiagnose                            
Error: 8(10) No.: 10988  0x2AEC Stickoxidsensor, Eigendiagnose                            
  error type: 1  (5442 ) Grenzwert 1 überschritten                                          
  readines Flag: (16 ) Testbedingungen erfüllt                                              
  error status:  (33 ) Fehler momentan nicht vorhanden, OBD-entprellt                       
  MIL - Status:  (48) Fehler verursacht kein Aufleuchten der Warnlampe (MIL)                
class :  11;  frequency: 1;   entry at km: (1.): 165712 km   (2.): 0 km   (n.): 0 km

The 30DA code has always been present with this car and never really posed a problem.

Here's a complete (detailed) readout of all the error memory on one instance.

===========================================================================================
$DATAID: 004 4DC0I 960S ICQ6S
 ===  13.06.2022  ===  17:21:56
DME partnumber: VAR_ECU_SERIAL_ECU
 
current kilometer reading: 166469 km
___________________________________________________________
 
comment line 1: 
comment line 2: 
___________________________________________________________
 
 
$error locationNr: 11802
$error locationtext: 0x2E1A Zündung, Zylinder 3                                       
57032E1A020013030924513B738A3400513B768F3400513C88903300
Error: 1(3) No.: 11802   0x2E1A Zündung, Zylinder 3                                       frequency: 9
  error type: 2  (4841 ) Brenndauer zu kurz                                                 
  readines Flag: (16 ) Testbedingungen erfüllt                                              
  error status:  (32 ) Fehler momentan nicht vorhanden, nicht OBD-entprellt                 
  MIL - Status:  (48) Fehler verursacht kein Aufleuchten der Warnlampe (MIL)                
  P-Code:        P1303 Zündkreisüberwachung Zyl. 3 - Brenndauer zu klein                  F_LZ: 36
ambient text   /   entry at               166368 km(n.) 166360 km(2.) 166360 km(1.) 
  Kühlmitteltemperatur OBD                 96.00 °C      78.00 °C      75.00 °C     
  Spannung Kl. 87                          14.62 V       14.52 V       14.02 V      
  Motordrehzahl                           1632.00 rpm   1664.00 rpm   1664.00 rpm   
  Funkenbrenndauer Zylinder 3               0.00 ms       0.00 ms       0.00 ms     
___________________________________________________________
 
$error locationNr: 10703
$error locationtext: 0x29CF Verbrennungsaussetzer, Zylinder 3                         
570329CF810003030224513BAAA53483513BB5933582000000000000
Error: 2(3) No.: 10703   0x29CF Verbrennungsaussetzer, Zylinder 3                         frequency: 2
  error type: 1  (5514 ) Einspritzung wird abgeschaltet                                     
  readines Flag: (16 ) Testbedingungen erfüllt                                              
  error status:  (32 ) Fehler momentan nicht vorhanden, nicht OBD-entprellt                 
  MIL - Status:  (49) Fehler wuerde das Aufleuchten der Warnlampe (MIL) verursachen         
  P-Code:        P0303 Verbrennungsaussetzer erkannt - Zylinder 3                         F_LZ: 36
ambient text   /   entry at               166360 km(2.) 166360 km(1.) 
  Motortemperatur                          87.75 °C      79.50 °C     
  Lastwert für Aussetzererkennung          57.42 %       64.45 %      
  Motordrehzahl                           1696.00 rpm   1664.00 rpm   
  Lambda Integrator Gruppe 1                1.56 %        2.34 %      
___________________________________________________________
 
$error locationNr: 12506
$error locationtext: 0x30DA Stickoxidsensor, Signal                                   
570330DA2200124D0128513F02004009000000000000000000000000
Error: 3(3) No.: 12506   0x30DA Stickoxidsensor, Signal                                   frequency: 1
  error type: 2  (4785 ) Signal nicht Verfügbar im Betrieb                                  
  readines Flag: (16 ) Testbedingungen erfüllt                                              
  error status:  (33 ) Fehler momentan nicht vorhanden, OBD-entprellt                       
  MIL - Status:  (48) Fehler verursacht kein Aufleuchten der Warnlampe (MIL)                
  P-Code:        P124D NOx-Sensorsignal (Bank 1) - nicht verfügbar im Betrieb             F_LZ: 40
ambient text   /   entry at               166392 km(1.) 
  Status NOx-Sensor                         2.00 -      
  Drehzahlgradient                          0.00 rpm/s  
  lineares Spannungssignal NOx-Sensor       1.00 -      
  Luftdurchsatz OBD                        23.04 g/s    
___________________________________________________________

As you can see, the cylinder that's misfiring has changed...


I initially faced this issue about 2 months ago, with exactly same symptoms on cyl4 so I immediately went and bought 6 delphi coils and ngk sparks and changed them. Issue then went away for about 1k miles.


Injectors are I guess healthy as confirmed by the state of the old sparks I've pulled out


Here is a pic of what I thought to be relevant INPA pages while cyl3 was misfiring





After a restart of the engine, it even goes into Stratified mode, which is usually a good sign...


Any ideas please? If you need any more info I can get this issue to happen again easily since it's consistent and I can provide you with whatever you need.

Many thanks!

[Mircea]

UPDATE:

Issue now consistently happens ONLY when engine is being driven cold. Doesn't matter how many times I restart it, it keeps misfiring.

Goes away completely after engine gets warm (>90*c) and I restart the engine.

No new codes to update