# 2003 Audi A4 3.0 Misfire mystery



## evolveVW (Nov 11, 2000)

I am inquiring for a friend I am trying to help chase his mystery misfires... here is some info.

Symptoms: Rough idle. Misfires at idle only. Rest of RPM range seems ok. When it happens, it happens regardless if the engine is hot or cold. 

Previous work:
All 6 coilpacks
Cam position sensors
Dealer looked at it last week, said coils were OK and there were no vacuum leaks.
Replaced MAF (granted with an Autozone unit I told him not to get!)
I replaced a few questionable vacuum lines as well.

The work I have done thus far:
Disconnected MAF while idling poorly, car runs smoothly with no misfires registered on any of the cylinders.
Ran a load test on the MAF using Block 2, 80% of HP number at peak flow rule. Came up with 75%
Took at look at block 32 to check idle fuel trims. When I first looked at them, they were 7.5%. AFter clearing the codes and driving it, 8.3%.
Misfires are only registered at idle. No 1 cylinder has a much larger number of misfire than another.
Used a vacuum pump to test for leaks in a few places, nothing I could find.
Coolant temp output seems OK.
Had bank 1 and 2 lean codes when I first pulled the codes. After clearing, running, and driving, these codes did not come back.
Oxygen sensors seem to be switching ok and displaying proper output.
Ran the Output Tests, everything seemed ok.

My initial reaction says MAF again, but I just want to rule everything out. The G42 Intake temp code did not duplicate after this scan. 

Here is the scan:

Chassis Type: 8E - Audi A4 B6/B7
Scan: 01 02 03 08 09 0F 11 15 16 17 18 36 37 45 46 55 56 57 65 67
69 75 76 77

VIN: WAULT68E92A248409 Mileage: 195180km/121279miles
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Address 01: Engine Labels: 06C-909-559-ASN.lbl
Part No SW: 8E0 909 559 D HW: 8E0 909 059 
Component: 3.0L V6/5V G 0003 
Coding: 0016751
Shop #: WSC 63351 000 00000
VCID: 3668D2573835

6 Faults Found:
16497 - Intake Air Temp. Sensor (G42): Signal too High 
P0113 - 002 - Lower Limit Exceeded - Intermittent
16684 - Random/Multiple Cylinder Misfire Detected 
P0300 - 008 - Implausible Signal - MIL ON
16688 - Cylinder 4: Misfire Detected 
P0304 - 008 - Implausible Signal - MIL ON
16690 - Cylinder 6: Misfire Detected 
P0306 - 008 - Implausible Signal - MIL ON
16689 - Cylinder 5: Misfire Detected 
P0305 - 008 - Implausible Signal - MIL ON
16685 - Cylinder 1: Misfire Detected 
P0301 - 008 - Implausible Signal
Readiness: 0010 1101

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Address 02: Auto Trans Labels: 01V-927-156.lbl
Part No: 8E0 927 156 J
Component: AG5 01V 3.0l5V USA 0809 
Coding: 0001002
Shop #: WSC 63351 000 00000
VCID: 356AD55B2533

1 Fault Found:
18265 - Load Signal: Error Message from ECU 
P1857 - 003 - Mechanical Failure - Intermittent
Freeze Frame:
RPM: 2944 /min
RPM: 2944 /min
RPM: 4000 /min
(no units): 2.0
Torque: -20.0 Nm
Temperature: 74.0°C
T.B. Angle: 0.0°
(no units): 5.0


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Address 03: ABS Brakes Labels: 8E0-614-517.lbl
Part No: 8E0 614 517 A
Component: ABS/ESP allrad 1726 
Coding: 04497
Shop #: WSC 06435 
VCID: 26480217E895

2 Faults Found:
01119 - Gear Recognition Signal 
35-10 - - - Intermittent
18265 - Load Signal: Error Message from ECU 
P1857 - 35-10 - - - Intermittent


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## [email protected] (Jul 19, 2010)

While factory specs say fuel trim readings can be +/- 10%, reality is they should be +/- 5%. I'm guessing you've got an intake leak somewhere.


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## vwemporium (May 27, 2002)

::::: WARNING EMERGENCY FORUM ACTION MESSAGE:::::

THIS POST VACATED BY JACK TO PROTECT CONTENT FROM FALLING INTO THE GAPING HOLE OF THE VORTEX! 

THIS SOLAR SYSTEM IS IN DANGER OF A BLACK-HOLE!
YOU TO CAN ESCAPE!
I CAN BE FOUND VIA THIS DHD STAR-GATE ADDRESS......
http://forums.ross-tech.com/member.p...European_Parts


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## evolveVW (Nov 11, 2000)

Update- Replaced intake manifold and TB gaskets, and all small vac lines. MAF is OE grade replacement and the air filter is clean. Issue is still present. Disconnecting the new MAF causes it to run worse, just like it should. The number of misfire codes has decreased, down to the Random code, and cylinders 4 and 6. It appears to still be running lean at idle, Lambda percentages are at +25%. Everything is smooth and within spec once engine is revved past idle. Any other ideas?


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## vwemporium (May 27, 2002)

::::: WARNING EMERGENCY FORUM ACTION MESSAGE:::::

THIS POST VACATED BY JACK TO PROTECT CONTENT FROM FALLING INTO THE GAPING HOLE OF THE VORTEX! 

THIS SOLAR SYSTEM IS IN DANGER OF A BLACK-HOLE!
YOU TO CAN ESCAPE!
I CAN BE FOUND VIA THIS DHD STAR-GATE ADDRESS......
http://forums.ross-tech.com/member.p...European_Parts


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## socalvag (Mar 28, 2011)

*3.0 Misfiring Status*

Have you been able to resolve the issue or did you give up?




evolveVW said:


> Update- Replaced intake manifold and TB gaskets, and all small vac lines. MAF is OE grade replacement and the air filter is clean. Issue is still present. Disconnecting the new MAF causes it to run worse, just like it should. The number of misfire codes has decreased, down to the Random code, and cylinders 4 and 6. It appears to still be running lean at idle, Lambda percentages are at +25%. Everything is smooth and within spec once engine is revved past idle. Any other ideas?


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## evolveVW (Nov 11, 2000)

Finally pinpointed that it was a bad PCV valve after replacing the other stuff at my friend's request. It was clogged full of clumped up oil/carbon.


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