Aceler8

UPDATE: So, when folks say to buy geniune Audi parts...believe them...at the end of my journey, all issues were traced to cheap PCV valves. I purchased a generic brand from eeuroparts and a Beck/Arnley. Neither worked properly. I decided to follow advice and purchase an OEM PCV valve and now all the problems are resolved.

++++++++++++++++++++++++++++++++++++++++++++++++++ ++++++++

disclaimer: i've searched and read everything i can from this site and google, but need help.

Audi is a 2006 USA model with 4.2 liter and 160,000 miles.
I'm having random misfires on the same bank/side(passenger) and a O2 sensor code (same side). I've run Vag com numerous times.

According to my tests, the MAF was on its way out so i replaced it. Post replacement, the rough idle and misfires stopped and it idled and drove great for that one day. Next day, the misfires and rough idle returned and are still there.

The car starts strong and idles ok...semi-rough idle, but after the engine warms up the misfires and very rough idle occur. The CEL begins to flash. When this happens i can hear what appears to be a relay clicking. The clicking is consistent with the misfires and seems to be in the dash on the driver side between the steering wheel and door (same place as the suspension relay).

However, once on the throttle, the car drives wonderful and i get 26mpg on highway...but once i come to a stoplight, the issues return.

I do have a small leak in the valve cover gasket, but this leak is on the driver's side so i don't suspect this is the cause.

What has been done:
- new spark plugs
- new PCV valve
- swap plug coils
- new 93 fuel with sea foam
- check for air leaks visually
- new Bosch MAF
- fuel filter is <40k miles old
- recent new air filter
- sprayed contact cleaner on O2 sensor plugs connector
- tighten manifold intake bolts

Here are codes...any advise?

Monday,20,February,2017,17:21:17:11676
VCDS -- Windows Based VAG/VAS Emulator Running on Windows 10 x64
VCDS Version: 16.8.3.1 (x64)
Data version: 20161010 DS267.0
Ross-Tech: Home


VIN: License Plate: FEB20



--------------------------------------------------------------------------------
--------------------------------------------------------------------------------


Address 01: Engine Labels: None
Control Module Part Number: 4E0 910 560 P HW: 4E0 907 560
Component and/or Version: 4.2L V8/5V G 0010
Software Coding: 0007773
Work Shop Code: WSC 02313 785 00200
VCID: 2E535C80B93AD9321E-807A
6 Faults Found:

16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 001 - - MIL ON
Freeze Frame:
Fault Status: 11100001
Fault Priority: 0
Fault Frequency: 2
Reset counter: 255
Mileage: 257392 km
Time Indication: 0

Freeze Frame:
RPM: 879 /min
Load: 32.1 %
Speed: 10.0 km/h
Temperature: 26.0°C
Temperature: 9.0°C
Absolute Pres.: 0.0 mbar
Voltage: 13.462 V

16685 - Cylinder 1
P0301 - 001 - Misfire Detected - MIL ON
Freeze Frame:
Fault Status: 11100001
Fault Priority: 0
Fault Frequency: 2
Reset counter: 255
Mileage: 257392 km
Time Indication: 0

Freeze Frame:
RPM: 879 /min
Load: 32.1 %
Speed: 10.0 km/h
Temperature: 26.0°C
Temperature: 9.0°C
Absolute Pres.: 0.0 mbar
Voltage: 13.462 V

16688 - Cylinder 4
P0304 - 001 - Misfire Detected - Intermittent
Freeze Frame:
Fault Status: 00100001
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 257392 km
Time Indication: 0

Freeze Frame:
RPM: 879 /min
Load: 32.1 %
Speed: 10.0 km/h
Temperature: 26.0°C
Temperature: 9.0°C
Absolute Pres.: 0.0 mbar
Voltage: 13.462 V

16686 - Cylinder 2
P0302 - 001 - Misfire Detected - MIL ON
Freeze Frame:
Fault Status: 11100001
Fault Priority: 0
Fault Frequency: 2
Reset counter: 255
Mileage: 257392 km
Time Indication: 0

Freeze Frame:
RPM: 879 /min
Load: 32.1 %
Speed: 10.0 km/h
Temperature: 26.0°C
Temperature: 9.0°C
Absolute Pres.: 0.0 mbar
Voltage: 13.462 V

18669 - Oxygen (Lambda) Sensor B1 S1
P2237 - 001 - Pump Current Open Circuit - MIL ON
Freeze Frame:
Fault Status: 11100001
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 257404 km
Time Indication: 0

Freeze Frame:
RPM: 1839 /min
Load: 45.5 %
Speed: 97.0 km/h
Temperature: 89.0°C
Temperature: 7.0°C
Absolute Pres.: 0.0 mbar
Voltage: 13.589 V

16687 - Cylinder 3
P0303 - 001 - Misfire Detected - MIL ON
Freeze Frame:
Fault Status: 11100001
Fault Priority: 0
Fault Frequency: 2
Reset counter: 255
Mileage: 257437 km
Time Indication: 0

03_AR_CO

Check this thread for your O2 code:

https://www.audiworld.com/forums/a8-...2868359/page2/

I had an identical error, and ended up replacing the harness side connector. All has been fair with the universe since.

MP4.2+6.0

+1. And I posted heavily in the referenced thread too.

You have a definitive 02 sensor issue from the codes. Clearly broken wire (bolded and underlined):
You may have other things too, but at least that. The harness issue is a known W12 problem with a TSB, but could infect others too. You won't be able to isolate though if it is the connector or the sensor without continuity testing from ECU to connector. Your choices short of that are a preemptive guess it is either the sensor or the connector (and wiring/terminals near or in it). Thus proceed to repair/replace one or the other and see if cured. If not, you need to go on to the other one too.

Aceler8

OK..thanks for the responses...i have a local store with the sensor in stock. May go that route first.

Interesting...we had a 2000 A6 with the 2.8 and it had at least 1 or 2 O2 sensor codes for years and never caused any idle or driveability issues.

Is the 4.2 that much more temperamental?

MP4.2+6.0

No. Had the 2000 A6 4.2. No big deal. SAI is temperamental on many Audi's, 4.2 included from my experience (and an older 2.8 in later years), but O2's not so much.

Among reasons I said you may not be to bottom of it. But your code on sensor is definitive--unless ECU is messed up or something extreme. If you unplug MAF it should run open loop and then you will know if basic running w/out the O2 MAF combo influencing mixture is either in the zone, or out to lunch. That will cause codes by itself of course, but tell you if it basically idles correctly or not. If not, maybe start to suspect something like injectors, injector seals, fuel pumps, and maybe other intake leak or combi valve (EGR and SAI) leak on that side.

If you know the Bosch # for the O2, I found Amazon was often cheapest.

gaber6

Check the airbox connection at the intake manifold at the rear of the engine. I had the same after messing with the air filter and the connection was letting unmetered air in at idle.

mcs

Have your fuel pumps flow tested. Make sure they isolate the main pump.

Riksta-22

Have the engine compression tested . If the miss firing cylinders are low on compression this could be down to carbon build up and the inlet valves could need cleaning ...

richard-tx

He does not have a FSI engine so carbon buildup is unlikely.

Aceler8

See my update on the first initial thread, but basically an OEM PCV valve (and maybe a MAF) fixed all my codes/issues.

Hopefully, this thread will help others in the future.