Misfire/Stumbling on Cold Start

   #1  

sclay115

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VCDS Serial number
C?ID=522163
Hi everyone, I've been bringing a 2010 2.0t Passat back from the dead, and the whole thing is just about sorted. There is a nagging issue with a cold start misfire, and I'm hoping that the folks who are more knowledgeable about what to look for, and when, can lend a hand. This is cross posted from the Vortex forum, and here is the original post below:

The issue first presented itself the morning after a longer than usual drive. Upon starting from dead cold, the engine would not stay running on it's own initially, would stutter, and then stall. If I proceeded to open up the throttle a bit, it would run (somewhat unhappily, but it would run). The odd behavior is that it would only do this for a short time, less than a few minutes, and then basically flatten right out into a happy idle. It would not gradually improve, it was as if there was an on/off switch to the issue. One second it would not idle, the next, fine.

Ambient temps in the high 50's Fahrenheit, and the issue seems to cease when the coolant temp reaches 50 Celsius, but I don't know the delay on the sampling.

The issue only happens when the engine is completely cold, and only for those first few minutes. No CEL present.

In my time of ownership, I've done what I can to take care of the usual 2.0tsi issues. Here is what I have done/replaced:

  1. Carbon cleaning (walnut shells)
  2. Coils (OEM)
  3. Plugs (OEM)
  4. Oil change
  5. Injector cleaner (not my magic bullet, but I had some laying around)
  6. MAF cleaned
Most of these were in response to a random multi cylinder misfire code, which occasionally presents itself when the engine isn't behaving as above. I have not seen a stored multi cylinder misfire after replacing the coils, but misfires are still being logged in VCDS on each cylinder. Note: No specific cylinder is favored, the misfires are on all cylinders equally.

In my time of ownership, as I do with most cars, I've gone through the engine bay for the details;

  • Checked/repaired any vacuum lines
  • Replaced air filter
  • Checked all host clamps/fitments
  • Verified all electrical connections are solid

This morning, the engine idled fine from cold (1200 rpm), but then when settling down to ~700 or so, the engine began logging tons of misfires, with a flashing CEL, but again, as above, after a short time, calmed down and drove as normal during and after several shut downs/restarts.

I'm fairly mechanically inclined, and can typically troubleshoot my own issues. I know that one of the big three (fuel, air, spark) is not happening in the right quantity, or at the right time. Without a more descriptive diagnostic code, I'm a little lost. It nearly seems as if there is a component that doesn't know that it has failed, so the system isn't seeing the trigger for the CEL.

Any inputs on where I should start? I realize I have this incredible tool in VCDS, but at this point, having looked at some of my logs, I very honestly don't know what to be tracking to hunt this down.

Some of the measuring blocks I've been logging (not all inclusive):

  1. Misfire count
  2. Misfire count/cylinder
  3. Throttle plate angle
  4. Fuel rail pressure expected
  5. Fuel rail pressure actual
  6. Fuel pump duty cycle
  7. Engine RPM
  8. Timing
  9. Coolant temp
  10. Ambient temp
  11. Fuel trim (block 32? I can't recall, but it's a percentage value)
If anyone has any other suggestions on blocks to be viewing, please let me know.

Any assistance would be appreciated, I am a VCDS rookie, but love the tool. I also very much enjoy this car and would like to sort it out completely. The diagnostic on this is specifically difficult as it only happens at dead cold, and that is only in the morning while I am trying to get my kiddo to daycare.

I am wondering if there is a block to view if the injectors are drowning the cylinders in fuel due to leakage, but I am not sure how to verify short of replacing the injectors. I am sure there is a better way to measure air/fuel ratio, but again, not sure which block to use. Fuel mileage does not seem to be suffering, 25-29 average depending on amount of highway trips. So leaky injectors seem unlikely.


Present me:
I had a user suggest that the MAF could be the issue, so I did a bit of digging to see how I could best test this with VCDS, and my follow up post was this:

Bringing some data back to this, I logged a cold start this morning coupled with a short drive around the block, and I noticed something interesting with the idle adaptation (or lack there of):


Rectangle Font Parallel Pattern Circle



As I understand it, there should be some short term fuel trimming happening in group 32.

You can also see that when the O2 sensor comes online into closed loop, the lambda control is pegged at 25%. Eventually, the mapping calms down:

Font Pattern Parallel Number Monochrome



But something does seem odd with the start up behavior.

I logged a WOT run (short one) to see about MAF behavior, and here is the readout:

Rectangle Font Parallel Circle Pattern



Seems like this is within normal spec, but any input is appreciated on that front.

With no adaption happening at idle, it would seem that the MAF could be the culprit, but there is certainly a challenge here with information overload.



Present me again:

Here is the autoscan:

Code:
Saturday,10,September,2022,08:27:35:52859
VCDS -- Windows Based VAG/VAS Emulator Running on Windows 10 x64
VCDS Version: 22.3.1.4 (x64)  HEX-V2 CB: 0.4615.4
Data version: 20220407 DS337.0
www.Ross-Tech.com


VIN: WVWXK7ANXAE065373   License Plate: 
Mileage: 301990km-187647mi   Repair Order: 


Chassis Type: AN-VW46 (3C0)
Scan: 01 02 03 08 09 15 16 17 19 1C 25 2E 42 44 46 52 53 56 62 65
          6D 72 77

VIN: WVWXK7ANXAE065373   Mileage: 301990km-187647miles

01-Engine -- Status: Malfunction 0010
02-Auto Trans -- Status: OK 0000
03-ABS Brakes -- Status: Malfunction 0010
04-Steering Angle -- Status: OK 0000
08-Auto HVAC -- Status: OK 0000
09-Cent. Elect. -- Status: OK 0000
15-Airbags -- Status: OK 0000
16-Steering wheel -- Status: OK 0000
17-Instruments -- Status: OK 0000
19-CAN Gateway -- Status: Malfunction 0010
1C-Position Sensing -- Status: OK 0000
25-Immobilizer -- Status: OK 0000
2E-Media Player 3 -- Status: Cannot be reached 1100
42-Door Elect, Driver -- Status: OK 0000
44-Steering Assist -- Status: OK 0000
46-Central Conv. -- Status: OK 0000
52-Door Elect, Pass. -- Status: OK 0000
53-Parking Brake -- Status: Malfunction 0010
56-Radio -- Status: Malfunction 0010
62-Door, Rear Left -- Status: OK 0000
65-Tire Pressure -- Status: OK 0000
6D-Trunk Elect. -- Status: Malfunction 0010
72-Door, Rear Right -- Status: OK 0000
77-Telephone -- Status: Cannot be reached 1100
-------------------------------------------------------------------------------
Address 01: Engine (CCT)       Labels:. 06J-906-026-CCT.clb
   Part No SW: 06J 906 026 DA    HW: 06J 906 026 DA
   Component: MED17.5 TFSI 2,0    6987  
   Revision: AAH11---    Serial number: VWZCZ000000000
   Coding: 0404010A1C070160
   Shop #: WSC 03189 444 12565
   VCID: 6C81C9FD6A8710DB037-8038
   VINID: 9E69E86C745EA115401850C70CB79A0901

5 Faults Found:
000768 - Random/Multiple Cylinder Misfire Detected 
               P0300 - 000 - 
             Freeze Frame:
                    Fault Status: 01100000
                    Fault Priority: 0
                    Fault Frequency: 1
                    Reset counter: 255
                    Mileage: 301991 km
                    Time Indication: 0
                    Date: 2017.01.31
                    Time: 08:13:01

             Freeze Frame:
                    RPM: 955 /min
                    Load: 41.6 %
                    Speed: 0.0 km/h
                    Temperature: 21.0∞C
                    Temperature: 16.0∞C
                    Absolute Pres.: 1000.0 mbar

000769 - Cylinder 1 
               P0301 - 000 - Misfire Detected
             Freeze Frame:
                    Fault Status: 01100000
                    Fault Priority: 0
                    Fault Frequency: 1
                    Reset counter: 255
                    Mileage: 301991 km
                    Time Indication: 0
                    Date: 2017.01.31
                    Time: 08:13:34

             Freeze Frame:
                    RPM: 951 /min
                    Load: 39.2 %
                    Speed: 0.0 km/h
                    Temperature: 28.0∞C
                    Temperature: 16.0∞C
                    Absolute Pres.: 1000.0 mbar

000771 - Cylinder 3 
               P0303 - 000 - Misfire Detected
             Freeze Frame:
                    Fault Status: 01100000
                    Fault Priority: 0
                    Fault Frequency: 1
                    Reset counter: 255
                    Mileage: 301991 km
                    Time Indication: 0
                    Date: 2017.01.31
                    Time: 08:13:34

             Freeze Frame:
                    RPM: 951 /min
                    Load: 39.2 %
                    Speed: 0.0 km/h
                    Temperature: 28.0∞C
                    Temperature: 16.0∞C
                    Absolute Pres.: 1000.0 mbar

000772 - Cylinder 4 
               P0304 - 000 - Misfire Detected
             Freeze Frame:
                    Fault Status: 01100000
                    Fault Priority: 0
                    Fault Frequency: 1
                    Reset counter: 255
                    Mileage: 301991 km
                    Time Indication: 0
                    Date: 2017.01.31
                    Time: 08:13:34

             Freeze Frame:
                    RPM: 951 /min
                    Load: 39.2 %
                    Speed: 0.0 km/h
                    Temperature: 28.0∞C
                    Temperature: 16.0∞C
                    Absolute Pres.: 1000.0 mbar

000770 - Cylinder 2 
               P0302 - 000 - Misfire Detected
             Freeze Frame:
                    Fault Status: 01100000
                    Fault Priority: 0
                    Fault Frequency: 1
                    Reset counter: 255
                    Mileage: 301991 km
                    Time Indication: 0
                    Date: 2017.01.31
                    Time: 08:13:34

             Freeze Frame:
                    RPM: 951 /min
                    Load: 39.2 %
                    Speed: 0.0 km/h
                    Temperature: 28.0∞C
                    Temperature: 16.0∞C
                    Absolute Pres.: 1000.0 mbar

Readiness: 0110 0101

-------------------------------------------------------------------------------
Address 02: Auto Trans        Labels: 02E-927-770.clb
   Part No SW: 02E 300 053 A    HW: 02E 927 770 AL
   Component: GSG DSG AG6     511 2106  
   Revision:    51112    Serial number: 00000910151439
   Coding: 0000020
   Shop #: WSC 05311 000 00000
   VCID: 1373B20117796F2362D-8046

No fault code found.

-------------------------------------------------------------------------------
Address 03: ABS Brakes        Labels:. 3C0-614-109-C4.clb
   Part No SW: 3C0 614 109 AF    HW: 3C0 614 109 AF
   Component: J104    C4 440 V2   0015  
   Revision: --025---    Serial number: 00000795814227
   Coding: 0000380
   Shop #: WSC 05311 000 00000
   VCID: 629DA7C5984356ABB9B-8036

1 Fault Found:
01314 - Engine Control Module 
            013 - Check DTC Memory - Intermittent
             Freeze Frame:
                    Fault Status: 00101101
                    Fault Priority: 3
                    Fault Frequency: 2
                    Reset counter: 135
                    Mileage: 301991 km
                    Time Indication: 0
                    Date: 2017.01.31
                    Time: 20:06:01

             Freeze Frame:
                    Speed: 0.0 km/h
                    Hex Value: 0x0000
                    Voltage: 14.00 V
                    Bin. Bits: 00011111
                    Count: 217
                    Hex Value: 0x0000


-------------------------------------------------------------------------------
Address 08: Auto HVAC (J301)       Labels:| 3C8-907-336.clb
   Part No SW: 3C8 907 336 AJ    HW: 3C8 907 336 AJ
   Component: Climatic      H14 0305  
   Revision: 00009001    
   Coding: 0000001002
   Shop #: WSC 05311 115 00000
   ASAM Dataset: EV_Climatic A01005
   ROD: EV_ClimaBasis_VW46.rod
   VCID: 75B7EC99354DD113EC9-8020

No fault code found.

-------------------------------------------------------------------------------
Address 09: Cent. Elect.        Labels:. 3C0-937-049-30-H.lbl
   Part No SW: 3C8 937 049 E    HW: 3C8 937 049 E
   Component: Bordnetz-SG     H54 2602  
   Revision: 00H54000    Serial number: 00000003432383
   Coding: 158C8F0340041A00470000000F00000000285D435C000120000000000000
   Shop #: WSC 05124 000 00000
   VCID: 3333128177398F2302D-8066

   Subsystem 1 - Part No: 3C1 955 419 B  Labels: 1KX-955-119.CLB
   Component: Wischer 150909 006  0208  
   Coding: 00046997
   Shop #: WSC 05124  

No fault code found.

-------------------------------------------------------------------------------
Address 15: Airbags        Labels: 5N0-959-655.lbl
   Part No SW: 5N0 959 655 H    HW: 5N0 959 655 H
   Component: J234__01T VW10 HI   1916  
   Revision: 20013000    Serial number: 003E1PMDEV82  
   Coding: 0012628
   Shop #: WSC 05311 000 00000
   VCID: 42DD4745388336AB99B-8016

   Subsystem 1 - Part No: 3C0 959 339 D
   Component: BF-Gewichtsens. 001 0002

   Subsystem 2 - Serial number: 00000000004VMU

   Subsystem 3 - Serial number: 0025.09.090000100000640013ˇÜ63

   Subsystem 4 - Serial number: 640013ˇÜ6332MTS636642679 ˇÜ63

   Subsystem 5 - Serial number: 42679 ˇÜ6342MTS648662769 ˇÜ63

   Subsystem 6 - Serial number: 62769 ˇÜ6351HTS6P1AA66KR ˇÜ63

   Subsystem 7 - Serial number: A66KR ˇÜ6361HTS6EVKV19KR ˇÜ63

   Subsystem 8 - Serial number: V19KR ˇÜ63727TS6201166KJ ˇÜ63

   Subsystem 9 - Serial number: 166KJ ˇÜ63827TS62M2266KR ˇ

   Subsystem 10 - Serial number: 266KR ˇ

No fault code found.

-------------------------------------------------------------------------------
Address 16: Steering wheel (J527)       Labels:| 3C0-953-569.clb
   Part No SW: 3C9 953 501 BG    HW: 5K0 953 569 T
   Component: LENKS.MODUL   009 0122  
   Revision: FF010E35    Serial number: 20091020100472
   Coding: 198A270002
   Shop #: WSC 05311 115 00000
   ASAM Dataset: EV_VW360SteerWheelUDS A03002
   ROD: EV_VW360SteerWheelUDS.rod
   VCID: 6FBBDEF15711EBC3265-803A

   Multifunction steering wheel control module: 
   Subsystem 1 - Part No SW: 3C8 959 537 D    HW: 3C8 959 537 D  Labels: 3C8-959-537.CLB
   Component: E221__MFL-TK6  H06 0022 
   Coding: E20000

No fault code found.

-------------------------------------------------------------------------------
Address 17: Instruments (J285)       Labels:| 3C8-920-xxx-17.clb-SRI1
   Part No SW: 3C0 920 972 L    HW: 3C0 920 972 L
   Component: KOMBI         H03 0305  
   Serial number: 00000000000000
   Coding: 261F00
   Shop #: WSC 05314 115 12345
   ASAM Dataset: EV_Kombi_UDS_VDD_RM09 A04052
   ROD: EV_Kombi_UDS_VDD_RM09_004_VW46.rod
   VCID: 2F3B1EF19791ABC3665-807A

No fault code found.

-------------------------------------------------------------------------------
Address 19: CAN Gateway        Labels:. 3C0-907-530-V3.clb
   Part No SW: 3C0 907 530 Q    HW: 3C0 907 951 
   Component: J533  Gateway   H13 0170  
   Revision:   H13       Serial number: 3420P09A240188
   Coding: FD807F07021612002002
   Shop #: WSC 05314 000 00000
   VCID: 2F3B1EF19B11ABC3665-807A

2 Faults Found:
01303 - Telephone Transceiver (R36) 
            004 - No Signal/Communication
             Freeze Frame:
                    Fault Status: 01100100
                    Fault Priority: 2
                    Fault Frequency: 15
                    Reset counter: 4
                    Mileage: 298997 km
                    Time Indication: 0

03272 - Control Module for Audio Interface 
            004 - No Signal/Communication
             Freeze Frame:
                    Fault Status: 01100100
                    Fault Priority: 2
                    Fault Frequency: 4
                    Reset counter: 7
                    Mileage: 299593 km
                    Time Indication: 0


-------------------------------------------------------------------------------
Address 1C: Position Sensing        Labels: 1Kx-919-xxx-1C.lbl
   Part No SW: 3C8 919 965     HW: 3C8 919 965 
   Component: Kompass         001 0001  
   Revision: 00001000    Serial number: 1614128T10PD02
   Coding: 0000002
   Shop #: WSC 05314 000 00000
   VCID: 75B7EC9939CDD113EC9-8020

No fault code found.

-------------------------------------------------------------------------------
Address 25: Immobilizer        Labels: 3C0-959-433-25.clb
   Part No SW: 3C0 959 433 AP    HW: 3C0 959 433 AP
   Component:    IMMO         052 0383  
   Revision: 00052000    Serial number: VWZCZ000000000
   Shop #: WSC 131071 1023 2097151
   VCID: 78A9E5AD2EDFAC7BF7F-802C

   Subsystem 1 - Part No: 3C0 905 861 H
   Component:    ELV          028 0380
   3C0905861H     ELV          028 0380   

No fault code found.

-------------------------------------------------------------------------------
Address 2E: Media Player 3
Cannot be reached

-------------------------------------------------------------------------------
Address 42: Door Elect, Driver        Labels:. 1K0-959-701-MIN3.clb
   Part No SW: 1K0 959 701 AR    HW: 1K0 959 793 N
   Component: J386  TUER-SG FT    1501  
   Revision: 72009005    Serial number: 00000628599013
   Coding: 0001205
   Shop #: WSC 05311 000 00000
   VCID: 7EA5F3B50CFB924BBD3-802A

No fault code found.

-------------------------------------------------------------------------------
Address 44: Steering Assist        Labels: 5N1-909-144.clb
   Part No SW: 5N1 909 144 K    HW: 5N1 909 148 G
   Component: J500__APA-BS KL.148 0703  
   Revision: 1AH03256    Serial number: 00092500351602
   Coding: 0000258
   Shop #: WSC 05311 000 00000
   VCID: 3A2D3FA550537E6BC1B-806E

No fault code found.

-------------------------------------------------------------------------------
Address 46: Central Conv.        Labels:. 3C0-959-433-46.clb
   Part No SW: 3C0 959 433 AP    HW: 3C0 959 433 AP
   Component:    KSG PQ46 RDK 052 0412  
   Revision: 00052000    Serial number: VWZCZ000000000
   Coding: 1A900E80D1030E362004141CF08A0F0E085801
   Shop #: WSC 05311 123 12345
   VCID: 78A9E5AD2EDFAC7BF7F-802C

   Subsystem 1 - Component:   Sounder n.mounted     

   Subsystem 2 - Component:       NGS n.mounted     

   Subsystem 3 - Component:      IRUE n.mounted     

No fault code found.

-------------------------------------------------------------------------------
Address 52: Door Elect, Pass.        Labels:. 1K0-959-702-MIN3.clb
   Part No SW: 1K0 959 702 AR    HW: 1K0 959 792 N
   Component: J387  TUER-SG BT    1501  
   Revision: 72009005    Serial number: 00000752399013
   Coding: 0001204
   Shop #: WSC 05311 000 00000
   VCID: 7F5B0EB10BF19B43B65-802A

No fault code found.

-------------------------------------------------------------------------------
Address 53: Parking Brake        Labels: 5N0-907-801.clb
   Part No SW: 3C8 907 801 E    HW: 3C8 907 801 E
   Component: J540 EPB3  VW-15417 0007  
   Revision:   010       Serial number: 00000000058156
   Coding: 0000057
   Shop #: WSC 05311 000 00000
   VCID: 2C0109FDAA07D0DB437-8078

1 Fault Found:
00532 - Supply Voltage B+ 
            002 - Lower Limit Exceeded - Intermittent
             Freeze Frame:
                    Fault Status: 00100010
                    Fault Priority: 1
                    Fault Frequency: 1
                    Reset counter: 189
                    Mileage: 298999 km
                    Time Indication: 0
                    Date: 2017.01.31
                    Time: 00:07:60

             Freeze Frame:
                    Voltage: 8.20 V
                    Count: 50
                    Speed: 0.0 km/h
                    Hex Value: 0x1260
                    Hex Value: 0x0001
                    Hex Value: 0x0101


-------------------------------------------------------------------------------
Address 56: Radio (J503)       Labels:. 5M0-035-1xx-56.clb
   Part No SW: 6RD 035 187 B    HW: 6RD 035 187 B
   Component: Radio         541 5614  
   Revision: --------    Serial number: VWZZZ4H6290655
   Coding: 16000400040005
   Shop #: WSC 127395 840 08317
   VCID: 46D55B5518AB0A8BB53-8012

3 Faults Found:
00856 - Radio Antenna 
            011 - Open Circuit - Intermittent
             Freeze Frame:
                    Fault Status: 00111011
                    Fault Priority: 5
                    Fault Frequency: 1
                    Reset counter: 221
                    Mileage: 27780 km
                    Time Indication: 0
                    Date: 2012.12.23
                    Time: 07:30:09

01305 - Databus for Infotainment 
            014 - Defective - Intermittent
             Freeze Frame:
                    Fault Status: 00101110
                    Fault Priority: 6
                    Fault Frequency: 3
                    Reset counter: 6
                    Mileage: 0 km
                    Time Indication: 0

02873 - Control Module for Back-Up Camera (J772) 
            004 - No Signal/Communication
             Freeze Frame:
                    Fault Status: 01100100
                    Fault Priority: 5
                    Fault Frequency: 1
                    Reset counter: 37
                    Mileage: 300737 km
                    Time Indication: 0
                    Date: 2017.01.31
                    Time: 06:47:47


-------------------------------------------------------------------------------
Address 62: Door, Rear Left        Labels:. 1K0-959-703-GEN3.clb
   Part No SW: 1K0 959 703 AD    HW: 1K0 959 795 P
   Component: J388   TUER-SG HL   0307  
   Revision: 42004101    Serial number: 00000001113587
   Coding: 0001168
   Shop #: WSC 05311 000 00000
   VCID: 72BDD78548A3C62BC9B-8026

No fault code found.

-------------------------------------------------------------------------------
Address 65: Tire Pressure        Labels: 3C0-959-433-65.lbl
   Part No SW: 3C0 959 433 AP    HW: 3C0 959 433 AP
   Component:    RDK              0453  
   Revision: 00052000    Serial number: VWZCZ000000000
   Coding: 0100101
   Shop #: WSC 131071 1023 2097151
   VCID: 78A9E5AD2EDFAC7BF7F-802C

No fault code found.

-------------------------------------------------------------------------------
Address 6D: Trunk Elect.        Labels: 3C9-827-383.clb
   Part No SW: 3C9 827 383 G    HW: 3C9 827 383 G
   Component: J605  HECKDECKEL    0730  
   Revision: 00H27001    
   Shop #: WSC 05314 000 00000
   VCID: 35372C99794D91132C9-8060

   Subsystem 1 - Part No: 3C9 827 384 G
   Component: J756  HECKDECKEL    0730

   Subsystem 2 - Serial number: 0900H27001001B0171ˇ

2 Faults Found:
00317 - Rear Lid Control Module (J605) 
            008 - Implausible Signal - Intermittent
             Freeze Frame:
                    Fault Status: 00101000
                    Fault Priority: 3
                    Fault Frequency: 254
                    Reset counter: 127
                    Mileage: 288653 km
                    Time Indication: 0
                    Date: 2015.11.10
                    Time: 22:42:01

03047 - Motor (in Trunk/Hatch control module) (V375) 
            011 - Open Circuit - Intermittent
             Freeze Frame:
                    Fault Status: 00101011
                    Fault Priority: 3
                    Fault Frequency: 26
                    Reset counter: 114
                    Mileage: 296902 km
                    Time Indication: 0
                    Date: 2016.04.13
                    Time: 03:23:52


-------------------------------------------------------------------------------
Address 72: Door, Rear Right        Labels:. 1K0-959-704-GEN3.clb
   Part No SW: 1K0 959 704 AD    HW: 1K0 959 794 P
   Component: J389   TUER-SG HR   0307  
   Revision: 42004101    Serial number: 00000001098186
   Coding: 0001168
   Shop #: WSC 05311 000 00000
   VCID: 73B3D28137B9CF23C2D-8026

No fault code found.

-------------------------------------------------------------------------------
Address 77: Telephone
Cannot be reached

End----------(Elapsed Time: 02:08, VBatt start/end: 14.4V/14.3V)-----------


Any help would be greatly appreciated. I believe I understand what the data is telling me, but what I don't really have a great grasp on, is why it is behaving the way it is.

Logically, if I get the gist of what I've read, is that if the lambda control is pegged at 25%, it is essentially telling me that it is seeing the leanest possible condition and doing what it can to compensate to the limit of its threshold (25%). But what I don't think I know what to look at is the corresponding values to see why, or if it is even effectively changing the map.

I do understand that air flow meters, MAF/AFM/etc, have a habit of going bad without them really knowing that they are broken. But they are not inexpensive, and it would be helpful to see if I can trouble shoot a bit further to gain some confidence.

I've also done the O2 sensor test (block 34?) and VCDS calls the sensor OK.

Long first post, but if I've learned anything by lurking on here, y'all would much rather have as much information as possible!

Really appreciate any help!
 
   #2  

EuroX

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Clear faults and check MVB/IDE channel for fuel trims MVB 32 on this car. If value is still pegged at 25% I would say MAF is fucked/dead. You can also try disconnecting the maf and see if runs any better.

The fact that the flow reading from the MAF are lower at 2440rpms than at 1280rpms leads me to believe something is not right with the MAF. It is possible than the MAF took a shit after cleaning. Personally I never bother cleaning the MAF if it needs a new one that's what it gets.

I would also check the PCV valve on top of the engine as they are known for failing so It wouldn't surprised me if that was the case or if you have a vacuum leak somwhere from a rear main seals or front engine covers or some sort of air intake leak.
 
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   #3  

Larry Manton

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Was reading this and will drop this on you. Had a 99 Jetta 2.0. Did exactly this when cold in the morning, but not every morning. Would start but just thrash, and maybe die, or not but ran bad.

Went through every part of the system, fuel, electrical and really wanted to condemn something, just buy it and move on. Just as you stated once running for a minute if you could keep it running, then, magically was sweet. Would not do it again all day, and maybe start next day or be fine till it was not. So induce why, was defiantly temp related, and what happens to oil when it gets warm, it thins.

I did a lot of test with a DSO, just to not condemn electrical, fuel pump waves, all of it. So one morning hooked a vac gauge up to it and would only pull about 14 when running like a pig. Would die then when I started it again after about say 2 minutes, Bang, vac instantly jumped to 20. Now I'm thinking this is obviously mechanical as a motor does not just decide to instantly breath better. Had it of been variable timing would also have looked at that, I miss simple.

So looking at it long and hard got to thinking rising temp fixed it as fine the rest of the day. So hooked up pressure gauge to the oil pump and had as I remember about 100psi from the pump. Went in and played with the over pressure part but did not fix. This by the way was a fairly new OEM pump as had rebuilt the motor. Replaced the pump with another one and did not think the numbers were that dynamic but seemed it dropped down to about 70 when cold, again was a while ago.

Problem solved and some may argue but my thought was the over pressure hyper hardened the hydraulic lifters. So for the fun of it, look at the vacuum numbers when this happens and see if it applies. I suppose MAF are in some way VAC numbers, but also might just be bad MAF numbers.

Also now we are back to oil, what type of oil, and is it the right stuff!!!!. Have had some oil classes and the game is not what it used to be. When they say they want X, that is exactly what they mean. Good luck.

Larimore
 
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sclay115

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Clear faults and check MVB/IDE channel for fuel trims MVB 32 on this car. If value is still pegged at 25% I would say MAF is fucked/dead. You can also try disconnecting the maf and see if runs any better.

The fact that the flow reading from the MAF are lower at 2440rpms than at 1280rpms leads me to believe something is not right with the MAF. It is possible than the MAF took a shit after cleaning. Personally I never bother cleaning the MAF if it needs a new one that's what it gets.

I would also check the PCV valve on top of the engine as they are known for failing so It wouldn't surprised me if that was the case or if you have a vacuum leak somwhere from a rear main seals or front engine covers or some sort of air intake leak.

Thanks for the reply! Forgot to mention, but OEM PCV valve and hoses were done also.

I did a bit more logging today, pulling block 32, here is what I found:

Below is the immediate startup log;


e3ev0D3.png


And here is the end of that short drive cycle (daycare drop off). You can see that the correction in trims are starting to take place:


t8bWPc8.png



I did a short WOT pull on the highway, as shown here:


VYzw7He.png


MAF numbers look okay? At least from what I've read.

What I found odd are the almost unmoving trim numbers while on the highway.

They do move, as shown by this table, which is constant speed on surface streets.


20Cv1sC.png


But once at speed, they lock in and don't move:


WmRvHFi.png


Which I don't specifically consider a bad thing, just an odd behavior.
 
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sclay115

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Was reading this and will drop this on you. Had a 99 Jetta 2.0. Did exactly this when cold in the morning, but not every morning. Would start but just thrash, and maybe die, or not but ran bad.

Went through every part of the system, fuel, electrical and really wanted to condemn something, just buy it and move on. Just as you stated once running for a minute if you could keep it running, then, magically was sweet. Would not do it again all day, and maybe start next day or be fine till it was not. So induce why, was defiantly temp related, and what happens to oil when it gets warm, it thins.

I did a lot of test with a DSO, just to not condemn electrical, fuel pump waves, all of it. So one morning hooked a vac gauge up to it and would only pull about 14 when running like a pig. Would die then when I started it again after about say 2 minutes, Bang, vac instantly jumped to 20. Now I'm thinking this is obviously mechanical as a motor does not just decide to instantly breath better. Had it of been variable timing would also have looked at that, I miss simple.

So looking at it long and hard got to thinking rising temp fixed it as fine the rest of the day. So hooked up pressure gauge to the oil pump and had as I remember about 100psi from the pump. Went in and played with the over pressure part but did not fix. This by the way was a fairly new OEM pump as had rebuilt the motor. Replaced the pump with another one and did not think the numbers were that dynamic but seemed it dropped down to about 70 when cold, again was a while ago.

Problem solved and some may argue but my thought was the over pressure hyper hardened the hydraulic lifters. So for the fun of it, look at the vacuum numbers when this happens and see if it applies. I suppose MAF are in some way VAC numbers, but also might just be bad MAF numbers.

Also now we are back to oil, what type of oil, and is it the right stuff!!!!. Have had some oil classes and the game is not what it used to be. When they say they want X, that is exactly what they mean. Good luck.

Larimore

Well that is a wild diagnosis!

The odd thing is that it isn't specifically linked to cold ambient air, just cold engine temps. I did recently change the oil (with the recommended goods), but I like the idea of pulling vacuum readings when it misbehaves next.
 
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EuroX

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How old is the fuel in this car and what brand and octane fuel are you using?? Also are plugs and coil audi original or aftermarket? And is the vehicle stock?? or have any hardware changes been implemented??
 
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sclay115

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How old is the fuel in this car and what brand and octane fuel are you using?? Also are plugs and coil audi original or aftermarket? And is the vehicle stock?? or have any hardware changes been implemented??

Entirely fresh fuel. It's been on the road a while, 93 octane. Coils/plugs are OEM spec (but not purchased from VAG), and vehicle has not been modified.

No other hardware changes, and the only VCDS programming I've implemented is the one touch unlock for all four doors, and to disable the rear view camera on the RCD330.
 
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EuroX

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I would suspect a vacuum leak, I recommend to check PCV valve for failure and check rear main seal. When Rear main seals fail on these engines they develop a vacuum leak same goes for PCV.
 
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sclay115

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I would suspect a vacuum leak, I recommend to check PCV valve for failure and check rear main seal. When Rear main seals fail on these engines they develop a vacuum leak same goes for PCV.

Thanks! Looks like there is an inspection port on the transmission side that I can use to try and diagnose. I don't see any major leakage from between the eng/trans, but seems like it could be fairly small and still cause an issue.

Out of curiosity, would a front crank or valve cover/cam cradle oil seal failure cause the same issue do you think?
 
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Thanks! Looks like there is an inspection port on the transmission side that I can use to try and diagnose. I don't see any major leakage from between the eng/trans, but seems like it could be fairly small and still cause an issue.

Out of curiosity, would a front crank or valve cover/cam cradle oil seal failure cause the same issue do you think?
Yes any sort of leaks from front or rear covers will cause a vacuum leak.
 
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Larry Manton

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Seen misfire counter come on at time 742, who and where??

MAF number moving around more than I would like but again this is predicated on the ability to breath. I know VAC leaks on these are major, but I'm not as versed on it as some of these guys.
 

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Follow up to this, been on the hunt for vacuum leaks (none found), but did replace the MAF with brand new, seems like the issue still persists.

Again, very odd, it will run very poorly, occasionally stalling from misfires, but only when cold. Once it crosses a specific threshold, everything flattens out and calms down, and runs perfect.

There are a few oil leaks (front cover), but I would imagine they would cause an issue at all engine temps, and the engine does not react to any oxidizer being sprayed in that area.

There seems to be a specific map, or sensor, or something misbehaving on a predetermined program during start up. But I am simply unsure where to look.

Another still odd behavior, this only happens in the morning, leaving for work, but does not reappear later in the day once the day's temperatures warm up a bit.
 

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Again, very odd, it will run very poorly, occasionally stalling from misfires, but only when cold. Once it crosses a specific threshold, everything flattens out and calms down, and runs perfect.
Sounds possibly like the cold start enrichment isn't happening, so my $0.02 would be to look into which temperature sensor(s) is/are used by the ECU to request a cold start.
 
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Sounds possibly like the cold start enrichment isn't happening, so my $0.02 would be to look into which temperature sensor(s) is/are used by the ECU to request a cold start.

That makes sense!

I did check the engine temperature sender readout this morning. At dead cold it is reading about 8 degrees above ambient, whether or not that makes a difference, I can't be sure. Worth it to replace to rule it out, they are inexpensive enough.

While logging this morning, I did notice something interesting. During the early stages of warmup, once the idle settles down, there is a cycle of:
  1. Running rough, CEL blinking on and off for misfires 30-60 seconds
  2. Idle picks up a hare, engine runs smooth, no misfires, no CEL 30-60 seconds
  3. Repeats to step one until engine is warmed up "enough" to stop misbehaving
Any idea what could be cycling itself on and off in that time period?

I logged some data this morning around idle control and timing. And during the cycle above, the ignition time is all over the place, not constant in any way. I am unsure if that is normal operation.
Idle adjustment is also bouncing around, from positive numbers to negative. Again, possibly normal as it is adjusting for the changing engine temperature, but it is a bit of challenge with no baseline.
 
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