07 S6 - VERY rough cold start. BAD Misfires at idle and under load

A6 All/ S6 All
#1

Hey guys, I’ve yet to post here but hope the V10 experts can help.

Bought the car a couple months ago out of state. CEL popped on an hour into my drive home. Slight misfires felt at idle. Idle slowly got more rough as the temps dropped here in Vermont. Cold start got worse each week to the point it would almost take 3 seconds to fire up then run rough (VERY) with a flashing CEL until things somewhat smoothed out (still misfiring).

Had a friend do a carbon cleaning at his shop. Definitely had a carbon issue. Replaced a very bad leak at the oil cooler which was spilling oil past the gasket, so that at least was fixed. Now the idle issue is worse. Before the cleaning I had a rough idle, but I could go WOT in gear without a flashing CEL, now I get stutters at nearly any throttle and get a flashing CEL if I go 3/4" lower RPM in 3rd gear. If I turn the car off after it’s fully warmed up and start it again, it’s a bit better.

Carbon is gone, plugs have been replaced, have only replaced one coil after codes were seen for cyl 5. I suspect the injectors are leaking/bad? From searching various forums I haven’t found a be all solution, but most successful threads ended with all injectors being replaced.

I also have a too lean at and off idle code, perhaps also related to the injector issue. I’ve been told it is most likely a vac leak near the intake, but so far haven’t found anything.

Your input is greatly appreciated!

Just scanned after two weeks driving after the carbon cleaning. This is Engine, Engine II and Engine other:

Address 01: Engine Labels: Redir Fail!
Control Module Part Number: 4F1 910 552 A HW: 4F1 907 552
Component and/or Version: 5.2L V10/4V FSI ª0040
Software Coding: 01050009190F0160
Work Shop Code: WSC 02335 785 00200
VCID: 2241E5D7FDDA0D2E6B-8076
3 Faults Found:

008567 - Bank 1; System Too Lean off Idle
P2177 - 001 - - MIL ON
Freeze Frame:
Fault Status: 11100001
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 154260 km
Time Indication: 0
Date: 2015.11.19
Time: 13:50:32

Freeze Frame:
RPM: 656 /min
Load: 12.9 %
Speed: 0.0 km/h
Temperature: 97.0°C
Temperature: 15.0°C
Absolute Pres.: 990.0 mbar
Voltage: 13.970 V

008585 - Bank 2; System too Lean at Idle
P2189 - 004 - - MIL ON
Freeze Frame:
Fault Status: 11100100
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 154260 km
Time Indication: 0
Date: 2015.11.19
Time: 13:50:33

Freeze Frame:
RPM: 642 /min
Load: 13.3 %
Speed: 0.0 km/h
Temperature: 97.0°C
Temperature: 15.0°C
Absolute Pres.: 990.0 mbar
Voltage: 14.097 V

006435 - Please Check DTC Memory of ECU Number 2
P1923 - 008 -
Freeze Frame:
Fault Status: 01101000
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 154753 km
Time Indication: 0
Date: 2015.11.25
Time: 15:05:23

Freeze Frame:
RPM: 0 /min
Load: 0.0 %
Speed: 0.0 km/h
Temperature: 70.0°C
Temperature: 54.0°C
Absolute Pres.: 980.0 mbar
Voltage: 11.176 V

Address 11: Engine II Labels: Redir Fail!
Control Module Part Number: 4F1 910 552 A HW: 4F1 907 552
Component and/or Version: 5.2L V10/4V FSI ª0040
Software Coding: 01050009190F0160
Work Shop Code: WSC 02335 785 00200
VCID: 2241E5D7FDDA0D2E6B-8076
7 Faults Found:

000768 - Random/Multiple Cylinder Misfire Detected
P0300 - 001 - - MIL ON
Freeze Frame:
Fault Status: 11100001
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 154175 km
Time Indication: 0
Date: 2015.11.17
Time: 19:46:58

Freeze Frame:
RPM: 3474 /min
Load: 96.0 %
Speed: 86.0 km/h
Temperature: 93.0°C
Temperature: 9.0°C
Absolute Pres.: 1010.0 mbar
Voltage: 13.462 V

000771 - Cylinder 3
P0303 - 001 - Misfire Detected - MIL ON
Freeze Frame:
Fault Status: 11100001
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 154175 km
Time Indication: 0
Date: 2015.11.17
Time: 19:46:58

Freeze Frame:
RPM: 3474 /min
Load: 96.0 %
Speed: 86.0 km/h
Temperature: 93.0°C
Temperature: 9.0°C
Absolute Pres.: 1010.0 mbar
Voltage: 13.462 V

000776 - Cylinder 8
P0308 - 001 - Misfire Detected - MIL ON
Freeze Frame:
Fault Status: 11100001
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 154188 km
Time Indication: 0
Date: 2015.11.18
Time: 18:55:41

Freeze Frame:
RPM: 1591 /min
Load: 41.6 %
Speed: 32.0 km/h
Temperature: 41.0°C
Temperature: 24.0°C
Absolute Pres.: 1000.0 mbar
Voltage: 14.224 V

000774 - Cylinder 6
P0306 - 001 - Misfire Detected - MIL ON
Freeze Frame:
Fault Status: 11100001
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 154194 km
Time Indication: 0
Date: 2015.11.18
Time: 20:11:41

Freeze Frame:
RPM: 749 /min
Load: 25.5 %
Speed: 15.0 km/h
Temperature: 57.0°C
Temperature: 23.0°C
Absolute Pres.: 1000.0 mbar
Voltage: 13.970 V

000777 - Cylinder 9
P0309 - 001 - Misfire Detected - MIL ON
Freeze Frame:
Fault Status: 11100001
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 154194 km
Time Indication: 0
Date: 2015.11.18
Time: 20:11:41

Freeze Frame:
RPM: 749 /min
Load: 25.5 %
Speed: 15.0 km/h
Temperature: 57.0°C
Temperature: 23.0°C
Absolute Pres.: 1000.0 mbar
Voltage: 13.970 V

000784 - Cylinder 10
P0310 - 008 - Misfire Detected - MIL ON
Freeze Frame:
Fault Status: 11101000
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 154194 km
Time Indication: 0
Date: 2015.11.18
Time: 20:33:32

Freeze Frame:
RPM: 679 /min
Load: 28.2 %
Speed: 8.0 km/h
Temperature: 57.0°C
Temperature: 30.0°C
Absolute Pres.: 1000.0 mbar
Voltage: 13.716 V

000775 - Cylinder 7
P0307 - 001 - Misfire Detected - MIL ON
Freeze Frame:
Fault Status: 11100001
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 154235 km
Time Indication: 0
Date: 2015.11.19
Time: 13:10:46

Freeze Frame:
RPM: 738 /min
Load: 19.6 %
Speed: 0.0 km/h
Temperature: 50.0°C
Temperature: 18.0°C
Absolute Pres.: 970.0 mbar
Voltage: 14.224 V

Address 31: Engine other Labels: Redir Fail!
Control Module Part Number: 4F1 910 552 A HW: 4F1 907 552
Component and/or Version: 5.2L V10/4V FSI ª0040
Software Coding: 01050009190F0160
Work Shop Code: WSC 02335 785 00200
Additional Info: 4F1910552A 5.2L V10/4V FSI ª0040
VCID: 2241E5D7FDDA0D2E6B-8076
Address 01: 3 Faults Found:
008567 - Bank 1; System Too Lean off Idle
P2177 - 001 - - MIL ON
Freeze Frame:
Fault Status: 11100001
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 154260 km
Time Indication: 0
Date: 2015.11.19
Time: 13:50:32

Freeze Frame:
RPM: 656 /min
Load: 12.9 %
Speed: 0.0 km/h
Temperature: 97.0°C
Temperature: 15.0°C
Absolute Pres.: 990.0 mbar
Voltage: 13.970 V

008585 - Bank 2; System too Lean at Idle
P2189 - 004 - - MIL ON
Freeze Frame:
Fault Status: 11100100
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 154260 km
Time Indication: 0
Date: 2015.11.19
Time: 13:50:33

Freeze Frame:
RPM: 642 /min
Load: 13.3 %
Speed: 0.0 km/h
Temperature: 97.0°C
Temperature: 15.0°C
Absolute Pres.: 990.0 mbar
Voltage: 14.097 V

006435 - Please Check DTC Memory of ECU Number 2
P1923 - 008 -
Freeze Frame:
Fault Status: 01101000
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 154753 km
Time Indication: 0
Date: 2015.11.25
Time: 15:05:23

Freeze Frame:
RPM: 0 /min
Load: 0.0 %
Speed: 0.0 km/h
Temperature: 70.0°C
Temperature: 54.0°C
Absolute Pres.: 980.0 mbar
Voltage: 11.176 V

Address 11: 7 Faults Found:
000768 - Random/Multiple Cylinder Misfire Detected
P0300 - 001 - - MIL ON
Freeze Frame:
Fault Status: 11100001
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 154175 km
Time Indication: 0
Date: 2015.11.17
Time: 19:46:58

Freeze Frame:
RPM: 3474 /min
Load: 96.0 %
Speed: 86.0 km/h
Temperature: 93.0°C
Temperature: 9.0°C
Absolute Pres.: 1010.0 mbar
Voltage: 13.462 V

000771 - Cylinder 3
P0303 - 001 - Misfire Detected - MIL ON
Freeze Frame:
Fault Status: 11100001
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 154175 km
Time Indication: 0
Date: 2015.11.17
Time: 19:46:58

Freeze Frame:
RPM: 3474 /min
Load: 96.0 %
Speed: 86.0 km/h
Temperature: 93.0°C
Temperature: 9.0°C
Absolute Pres.: 1010.0 mbar
Voltage: 13.462 V

000776 - Cylinder 8
P0308 - 001 - Misfire Detected - MIL ON
Freeze Frame:
Fault Status: 11100001
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 154188 km
Time Indication: 0
Date: 2015.11.18
Time: 18:55:41

Freeze Frame:
RPM: 1591 /min
Load: 41.6 %
Speed: 32.0 km/h
Temperature: 41.0°C
Temperature: 24.0°C
Absolute Pres.: 1000.0 mbar
Voltage: 14.224 V

000774 - Cylinder 6
P0306 - 001 - Misfire Detected - MIL ON
Freeze Frame:
Fault Status: 11100001
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 154194 km
Time Indication: 0
Date: 2015.11.18
Time: 20:11:41

Freeze Frame:
RPM: 749 /min
Load: 25.5 %
Speed: 15.0 km/h
Temperature: 57.0°C
Temperature: 23.0°C
Absolute Pres.: 1000.0 mbar
Voltage: 13.970 V

000777 - Cylinder 9
P0309 - 001 - Misfire Detected - MIL ON
Freeze Frame:
Fault Status: 11100001
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 154194 km
Time Indication: 0
Date: 2015.11.18
Time: 20:11:41

Freeze Frame:
RPM: 749 /min
Load: 25.5 %
Speed: 15.0 km/h
Temperature: 57.0°C
Temperature: 23.0°C
Absolute Pres.: 1000.0 mbar
Voltage: 13.970 V

000784 - Cylinder 10
P0310 - 008 - Misfire Detected - MIL ON
Freeze Frame:
Fault Status: 11101000
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 154194 km
Time Indication: 0
Date: 2015.11.18
Time: 20:33:32

Freeze Frame:
RPM: 679 /min
Load: 28.2 %
Speed: 8.0 km/h
Temperature: 57.0°C
Temperature: 30.0°C
Absolute Pres.: 1000.0 mbar
Voltage: 13.716 V

000775 - Cylinder 7
P0307 - 001 - Misfire Detected - MIL ON
Freeze Frame:
Fault Status: 11100001
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 154235 km
Time Indication: 0
Date: 2015.11.19
Time: 13:10:46

Freeze Frame:
RPM: 738 /min
Load: 19.6 %
Speed: 0.0 km/h
Temperature: 50.0°C
Temperature: 18.0°C
Absolute Pres.: 970.0 mbar
Voltage: 14.224 V

#2

Welcome your in good hands here

From the look of the codes you should change the coil packs as you have issues on other cylinders

Without knowing what other maintenance work has been done it’s hard to know what else you might need.

A few things

The SAI system pumps air into the cylinder heads for emissions. That usually lasts about 1 to 3 min after start up. That can cause the car to run rough. But it looks like you have other issues as well

You really should replace all the other coil packs as you still have misfires on other cylinders
Check for a vac leak
Look at the fuel filter and start pouring in injector cleaner. Redline is very aggressive and will help clean injectors

Injectors can get damaged if the carbon went unchecked for too long. But the other things I mentioned need to get changed anyways so it’s good to start there

#3

Have you tried removing the oil cap with the engine running and if you try is there an excessive vacuum?

#4

Thank you for the welcome!

I just saw barryrs post about the oil cap - funny you should ask. After flying out to get the car, I noticed a high pitch whistle/screech from the rear of the motor. It would seem to go away for a split second if the throttle was blipped. I removed the oil cap and the noise/vacuum went away. This lead to an additional two days out of state while the car dealer had it “fixed” at the local Audi dealer. It wasn’t making noise when it arrived (of course) but they supposedly changed the PCV valve. Noise was gone, car ran much better, but then the CEL came on a couple hours into my drive home with normal driving. I will call the dealer tomorrow to have them look up exactly what was replaced at that visit.

To justincredible:

I may as well change the other coils since they are relatively inexpensive. I’ll order them up and install ASAP.

As for maintenance work, it was a single owner car, dealer maintained. There was a no questions asked fix it policy at the dealer by the owner. Long story short it’s had all major milestone services done at the dealer. Car is a 95k now.

Carbon has been an issue for some time now. I don’t believe it had ever been done at the dealer. So damage could have been done to the injector. I will also confirm while talking to dealer.

I have run a seafoam treatment (gas and intake), which didn’t seem to help at all.

Understood about the SAI system. Initially when the car starts, it runs seemingly without any misfires as it idles higher around 1k. After about 30 seconds it settles down under 1k RPM then runs very rough. Literally bounces you a bit in the seat, flashing CEL etc… after a minute it will turn a solid CEL and a bit less rough.

I will order up the coil packs. If you have any other suggestions or thoughts please do let me know.

Thank you so much!

#5

It could be an issue with the 3 stage fine oil separator as shown in this picture.

http://forum.rs246.com/download/file.php?id=31721&mode=view

There is a spring operated piston that moves with the increase in crank case pressure to bring into operation the 3 oil separators which can jam up.

This was very obvious on my car as the oil filler cap was very difficult to remove with the engine running like in this example - https://www.youtube.com/watch?v=6gXO6v49nnE

The noise you are reporting also leads me to think its the oil separator as i had the same symptoms

#6

Thanks so much for the diagram, that’s very helpful. I don’t have the noise any longer that I was experiencing when I fist went to buy the car. I didn’t see the final bill from the dealer, but I was told by the auto seller that had it serviced, that the Audi tech said “you won’t experience that noise ever again…” - I need to inquiry about exactly what was fixed.

Local dealer only has 7 coil packs in stock. They are about $8 more per coil than online, but given they are available now for install over the weekend I’ll look at codes that were pulled and replace cyls that are most problematic. We’ll see if that smooths things out at all.

I do know that some clips are broken on the harness leading to coils. Perhaps these are backing off a tad or have some play in them. I really don’t want to get into re wiring heads on those.

Thank you for the help everyone. I’ll update you after the coils are in.

#7

Good idea. Get the coil packs install them and then see how it goes.

#8

Update:

All new coils installed. Noticed some oil around #3 coil, appears VC gasket is leaking a bit.

Also noticed there is still a very strong suction/vacuum behind the oil cap. Car stumbles if removed. Can clearly hear a restriction in vacuum from the rear when the cap is placed back on. Referring back to the oil separator diagram from barryrs it could be caused by a bad separation valve which includes the pressure regulator, or perhaps the feed or return hose thats connected to the check valve in the V-channel? Also, oil in #3 could be due to access pressure in the head?

After a few minute running I still have misfires on multiple cyl. Is there any way to really test the oil separator valve? I wouldn’t be able to inspect or repair any of the hoses at the check valve without removing the intake manifold. My guy that did the carbon cleaning didn’t notice anything out of the ordinary while in there.

Also have “Please Check DTC Memory of ECU Number 2” - unsure exactly what this means. Hoping it’s not a core issue with ECU #2 which I’ve hard happening.

Replace oil separation valve for starters? Thank you for the help. Need to get this sorted soon as it’s my current daily driver. Luckily I’m a photographer and work mainly from home.

Codes I just pulled:

1 Fault Found:
006435 - Please Check DTC Memory of ECU Number 2
P1923 - 008 -
Freeze Frame:
Fault Status: 01101000
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 154753 km
Time Indication: 0
Date: 2015.11.30
Time: 08:36:29

         Freeze Frame:
                RPM: 0 /min
                Load: 0.0 %
                Speed: 0.0 km/h
                Temperature: 0.0∞C
                Temperature: 2.0∞C
                Absolute Pres.: 980.0 mbar
                Voltage: 11.176 V

5 Faults Found:
000768 - Random/Multiple Cylinder Misfire Detected
P0300 - 001 -
Freeze Frame:
Fault Status: 01100001
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 154753 km
Time Indication: 0
Date: 2015.11.29
Time: 16:14:58

         Freeze Frame:
                RPM: 1107 /min
                Load: 31.0 %
                Speed: 0.0 km/h
                Temperature: 25.0∞C
                Temperature: 8.0∞C
                Absolute Pres.: 970.0 mbar
                Voltage: 13.970 V

000771 - Cylinder 3
P0303 - 001 - Misfire Detected
Freeze Frame:
Fault Status: 01100001
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 154753 km
Time Indication: 0
Date: 2015.11.29
Time: 16:14:58

         Freeze Frame:
                RPM: 1107 /min
                Load: 31.0 %
                Speed: 0.0 km/h
                Temperature: 25.0∞C
                Temperature: 8.0∞C
                Absolute Pres.: 970.0 mbar
                Voltage: 13.970 V

000776 - Cylinder 8
P0308 - 001 - Misfire Detected
Freeze Frame:
Fault Status: 01100001
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 154753 km
Time Indication: 0
Date: 2015.11.29
Time: 16:15:30

         Freeze Frame:
                RPM: 1106 /min
                Load: 30.2 %
                Speed: 0.0 km/h
                Temperature: 29.0∞C
                Temperature: 7.0∞C
                Absolute Pres.: 970.0 mbar
                Voltage: 13.970 V

000775 - Cylinder 7
P0307 - 001 - Misfire Detected
Freeze Frame:
Fault Status: 01100001
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 154753 km
Time Indication: 0
Date: 2015.11.29
Time: 16:17:21

         Freeze Frame:
                RPM: 673 /min
                Load: 23.5 %
                Speed: 0.0 km/h
                Temperature: 42.0∞C
                Temperature: 8.0∞C
                Absolute Pres.: 970.0 mbar
                Voltage: 13.843 V

000769 - Cylinder 1
P0301 - 002 - Misfire Detected
Freeze Frame:
Fault Status: 01100010
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 154753 km
Time Indication: 0
Date: 2015.11.29
Time: 16:20:52

         Freeze Frame:
                RPM: 669 /min
                Load: 20.0 %
                Speed: 0.0 km/h
                Temperature: 53.0∞C
                Temperature: 9.0∞C
                Absolute Pres.: 970.0 mbar
                Voltage: 14.097 V
#9

I just read though this thread and it reminded me a lot of the 4.2 FSI V8 S5 coupe that I recently had to work on. The 5.2 FSI V10s are based on the 4.2 FSI V8s so they are really similar. You can read about it here: http://audirevolution.net/forum/index.php?topic=3781.msg109808#msg109808

If you can feel a very strong suction/vacuum behind the oil cap with the engine running and there is a noise from the back of the engine then I would definitely replace your PCV valve/oil separator asap. Once you get the old one off then just pop the large black cap off the back to look at the diaphragm. The one on the S5 that I worked on was torn. That was causing the engine to suck engine oil into the intake manifolds at idle. That bad PCV valve/oil separator was causing cold start misfires and misfires under load on the S5 from the oil going into the cylinders.

The “Please Check DTC Memory of ECU Number 2” fault code is just telling you to look at the other ECU. The 5.2 FSI V10s use a Master-Slave system for communication between the two ECUs because the processing power of the ECUs in 2007 and 2008 couldn’t handle all the different signals and solenoids with just one ECU. I see that kind of fault code a lot on the newer cars because the different computers communicate back and forth so much. For example, the newer B8 cars are very interconnected for the different control modules/computers so seven different control modules can have faults saying to check a certain module and then only that one control module actually has a fault for something.

The oil around the ignition coil for cylinder 3 could be from the valve cover gasket or the camshaft ladder frame seal. I wouldn’t worry about it right now unless it is really bad. By the way, the V10s have an individual seal for each spark plug tube hole in the camshaft ladder frame. V8a6 posted about it in the S6 Dump Thread: http://audirevolution.net/forum/index.php?topic=2614.msg86261#msg86261

What would really worry me is the lean codes at and off idle that you were posting about before in your first post. Yes, lean codes can be caused by a vacuum leak but they can also be caused by not getting enough fuel either. So if your fuel injectors are not working correctly. That was the last thing that I had to replace on that S5 and they were $106 with tax each for a total of $848 for 8 of them.

#10

Good suggestions above.

I recently had some similar issues on my car (also 100k miles). They’re all now resolved.

I personally removed my intake manifold and cleaned all the carbon out, installed some intake spacers at the same time. I also noticed oil in the spark plug tubes, imo- they were all the camshaft ladder frame seals, not the valve covers. I didn’t feel like pulling my whole motor… so I just cleaned them up and will monitor them.

I didn’t replace my coil packs. Odds of all 10 coil packs failing at the same time are extremely low. Typically random misfires are caused elsewhere.

In addition to replacing the PCV/Oil Separator, check the crossover hose (the one that goes from the oil separator and then to each valve cover in the above illustration) for any cracks. It’s plastic and gets extremely brittle with age, and as I discovered, nearly impossible not to crack when removing your intake manifold. Rather than spend the $250 on a new hose from the dealer, I simply cut off the long section and replaced it with 3/4" hose. Fixed that hose and haven’t had the engine light come back since.

Lastly, double check your connectors on the front of your intake manifold. The cold start issue could be as simple as the connectors not being seated all the way, or the arms for the motor/flaps interfering with something on the front of the motor. The outer flaps are the ones that effect cold starts. After installing my manifold spacers the actuator arm was being interfered with one of the brackets on the front of the motor (because the manifold now sat 10mm higher). tweaked the bracket so it wasn’t causing any interference and the cold start issues disappeared.

#11

Update:

I was about to order a new oil separator when I thought it may make sense to inspect the one in the car first. I can seal the inlet and blow air through. If it was in need or replacement would it allow for air to pass through? Not sure how to test this. Should I just buy another?

I was looking for vacuum leaks and found that the Throttle body is leaking. Top left mounting position seems stripped/bending/cracking not allowing snug fit to the intake. You can hear and feel air being sucked in here post TB. I know this wouldn’t account for the crankcase vacuum issue, though it could be to blame for the lean codes? Short of a new intake housing I could possibly get a longer bolt and slip a nut on the back side to pull it together tightly.

Video: https://www.flickr.com/photos/14022792@N06/23060470379/in/album-72157661283835280/
Photo:https://www.flickr.com/photos/14022792@N06/23428448595/in/album-72157661283835280/
https://www.flickr.com/photos/14022792@N06/23060470799/in/album-72157661283835280/

Video of crankcase suction: https://www.flickr.com/photos/14022792@N06/23132682480/in/album-72157661283835280/

I did see what appears to be a hairline crack in the intake manifold. Doesn’t appear to be sucking air at all though:
https://www.flickr.com/photos/14022792@N06/23428448415/in/album-72157661283835280/

Without knowing for sure how to test the oil separator should I order one? Could it be post separator hose under the intake manifold?

#12

If you think there is a vac leak. Try spraying starter fluid in the area that you think the leak is coming from. If the motor is pulling in the starter fluid due to a vac leak the starter fluid will act as a secondary fuel and you will hear the rpm rise. Its a good start

#13

Thank you JRach and JimmyBones for the replies. All very helpful. I will be further inspecting the breather hose.

I finally got a hold of the Audi dealer in Indiana that had the car before I brought it home. They did in fact replace the oil separator, so that should in theory be OK.

I’m just not quite sure whats going on. Started the car up and let it idle for 10 min or so, rough idle to start. Rough going down the road to my local grocery store (5 miles) under load with minimal throttle. Car sat for 45 min. On the way home things felt much more normal and I was able to go WOT without any hesitation or flashing CEL.

Cleared codes after getting home and went out for a spirited drive. I basically threw everything I could at it. low RPM WOT pulls, standing to top of 3rd flat out… no CEL. Still settled into an idle with misfires but not violent. I pulled the codes and things look much better than before.

We’ll see how it starts and runs after a cold night. #3 was the coil with oil. I’m fairly sure I’ll get a flashing CEL. I’ll need to tighten up or seal that leak post MAF at the TB. That may calm the cold idle issue.

Next step is looking for any other vac leaks. Will then pull the intake manifold and inspect the lower hoses of the oil separator leading to the check valve. If #3 and #8 are consistent with misfires I’ll most likely have two fuel injectors to install while the manifold is off.

What could cause such a drastic change in operation at warmer engine temps??

3 Faults Found:
000768 - Random/Multiple Cylinder Misfire Detected
P0300 - 008 -
Freeze Frame:
Fault Status: 01101000
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 154783 km
Time Indication: 0
Date: 2015.11.30
Time: 18:33:37

         Freeze Frame:
                RPM: 1715 /min
                Load: 37.6 %
                Speed: 34.0 km/h
                Temperature: 84.0°C
                Temperature: 31.0°C
                Absolute Pres.: 970.0 mbar
                Voltage: 13.970 V

000771 - Cylinder 3
P0303 - 008 - Misfire Detected
Freeze Frame:
Fault Status: 01101000
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 154783 km
Time Indication: 0
Date: 2015.11.30
Time: 18:33:37

         Freeze Frame:
                RPM: 1715 /min
                Load: 37.6 %
                Speed: 34.0 km/h
                Temperature: 84.0°C
                Temperature: 31.0°C
                Absolute Pres.: 970.0 mbar
                Voltage: 13.970 V

000776 - Cylinder 8
P0308 - 008 - Misfire Detected
Freeze Frame:
Fault Status: 01101000
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 154783 km
Time Indication: 0
Date: 2015.11.30
Time: 18:33:37

         Freeze Frame:
                RPM: 1715 /min
                Load: 37.6 %
                Speed: 34.0 km/h
                Temperature: 84.0°C
                Temperature: 31.0°C
                Absolute Pres.: 970.0 mbar
                Voltage: 13.970 V
#14

Your codes are for missfires at part throttle and part load. When you see that and you dont have any fuel codes its best to get agressive with a fuel injection cleaner. I would start putting in fuel injector cleaner every time you fill up the car.

As long as your cyl 8 and cyl 3 plugs and coil packs are replaced there shouldnt be any issues with those

#15

I haven’t started the car since pulling the codes on Monday. I’ll be taking it out later this morning so we’ll see how the cold start is. I may use a small strip of RTV if I have it to seal up the TB leak before starting.

Is there a specific treatment you recommend? I’ve only used Seafoam in the past. OK to use a can on less than a full tank to be more aggressive?

#16

So I’m getting some where… New coils were put in, but the car was still running very rough the first few cold starts. Once warmed up it was much better.

Misfires on 3/8 last I checked. Nothing hard enough to throw a CEL.

I laid a thin bead of RTV blue advanced along the vac leak I found between the intake plenum and throttle body. Short term solution however that’s fixed a majority of the idle misfires and cleared up the too lean at and off idle codes.

Running much better and very strong compared to where I was last week. Going to clear the codes again and pull them after some driving with the intake leak resolved.

If I still have a part throttle misfire from 3/8 I may need to replace those two injectors. I have another can of seafoam going in the tank today, so hoping that clears things right up.

Thank you all for the help. I’ll keep you posted on the next week or driving.

#17

ok first off the vac leak is a big deal. You need to make sure that is fixed that will cause all kinds of issues. Lean off idle is a big vac leak issue and missfires are going to be a big issue for missfire codes.

Seafoam is good to keep with it.

#18

Agreed. I can’t believe I didn’t find that leak earlier. I’m sure the coil replacement wasn’t entirely necessary. Leak is sealed up for now. It appears the mount on the intake plenum (top left point) is stripped leaving a small gap and a bit cracked. I will try to threat a longer bolt through and use a nut to pull and tighten things up. I’m sure I’ll need a new intake plenum at some point, so I’ll start looking around the web.

The car and myself are much happier campers at the moment.

#19

Thats always good to hear. Nice job getting to the bottom of the issue

#20

Reviving the topic from the dead!!!

Just got the car back from the shop. They did the valve cover gaskets, spark plugs, and some other stuff.

Still has misfires, and all the symptoms of a bad air oil separator. I happen to have a brand new one sitting here, that I ordered awhile back when someone on AR posted a cheap link on amazon. Now, all I need is a writeup DIY install.

Does anyone have a step-by-step DIY AOS install for the v10 S6?