Unrelenting misfires S6 V10. New member

A6 All/ S6 All
#1

Hello all!
I mainly reside on audizine, however I was told to head over here if I needed anymore help with my S6. Which I do. It has now been in the shop since september, with terrible misfires. First issue: oil leaking into the sparkplugs. Spark plug tube seals replaced. Still misfiring in cylinders 9 and 10 so they checked the fuel injectors, and replaced those. Still misfiring in 9/10. Checked fuel pumps and found out one of them was running at 6 bar, very low. Replaced. Ran better, still misfired. Other fuel pump was also running low. Replaced. Ran great! No more misfires in cylinders 9/10! But now on a cold startup there are horrible misfires in the middle 4 cylinders. Shop got Fed up with this, so they called out an Audi specialist or something. Any ideas on what next? Apparently after the car warms up it runs great. Thanks.

Irish.

#2

Hey Irish!

Finally, you made it over here. I have added a lot of your stuff to the Info Dump, so thanks for sharing your experience.

Can you provide a pull of all the current codes?
Is there any chance the issue with misfires on #4 could have something to do with the coilpack connection? Here are two accounts with slightly different fixes

http://forums.ross-tech.com/showthread.php?84-07-Audi-S6-5-2L-V10-MAF-sensor-logging&p=1301&viewfull=1#post1301

http://www.audiworld.com/forums/a6-s6-c6-platform-discussion-58/2007-5-2-s6-misfire-saga-2877024/

I am not the most Technical guy here, so await advice from others.

Justincredible and JimmyBones are two guys who are often quick to help with solid advice.

#3

Well we have a deep collection of guys who are master technicians master mechanics and just masters at the trade of working to help guys solve these difficult to track down issues.

Few questions.

Do you still not have the car.
Do you have a vag com
Are you mechanically able to work on the car
How many miles are on the car
How many miles since
carbon clean
Fuel filter
Plugs and packs
And new 02s

That should start telling n the story. The other part is getting us any other codes and getting us exactly what cylinders are missfireing

#4

Yes I still own the car, the dealership is in possession as of now
No vag com
Not able to work on the car.
62k miles
Had first carbon clean at 55k miles. Shop just did one for me for free week before christmas just in case.
Shop replaced coils/sparkplugs in misfiring cylinders.
Idk about fuel filter
O2 sensors replaced over summer.

I do not have the codes, however I believe cylinders 2-3, and 7-8. Can update later. Thanks

#5

When you first got the car did it do this misfire issue then or did it pop up over time

The exact codes the car has ever received will be helpful if you can get them. Did you get pictures of the carbon clean results. Also exactly what parts were replaced by the dealer would be helpful. So if they just replaced plugs in X cylinders it’s super helpful to know that.

Your in the right place we will help you get it sorted out. Right now it’s great that the warranty is covering it.

#6

The first carbon clean I did get a picture of. It was perfect. I saw before pics of carbon clean on the 2nd one, the carbon buildup was minimal. I had the car about a year before the misfire happened. One day during this summer my CEL blinked 3 times while driving. Never heard anything from that for about another month until it happened again. Then one day in September the CEL started blinking and it was misfiring horribly. I believe the sparkplugs were replaced in the misfiring cylinders. I know that the plugs have been replaced in the misfiring cylinders but I will get back to you with more specific information later.

#7

If no work or nothing out of the normal was changed just weeks before the miss fires then a coil pack and plug swap would probably have fixed it. Especially if you got no codes.

If you get one coil pack that failed you should have replaced all of them. They tend to fail at the same rate. Find out exactly what coils and plugs that were changed. That’s the place to start. Because there are lots of cases like yours where one cylinder misfires the dealer only changes the one cylinder and then two weeks later another cylinder goes down. And that keep happening over and over. Cold start missfireing can be from a coil pack or plug that is weak and the system hasn’t warmed up yet. And the miss fires don’t get logged during some parts of warm up.

If you can provide as much parts data as you can.

#8

Alright, sorry it took so long. As of right now, the car is still misfiring. ALL COILS AND SPARKPLUGS HAVE NOW BEEN REPLACED. The fuel injectors in cylinders 5/10 have been replaced, none others. After that, the misfires have now progressed.
Here are the current codes being thrown:
P0300
P030303
P0304
P0309

There was another instance of a member getting his misfires fixed after fuel injectors replaced. That’s what I’m thinking now. Any idea? Thanks

#9

OK did they inspect the intake manifold to make sure it was updated. If the intake is letting cross bleeding you will get miss fires. Also if you can get us the full vagcom code that would be helpful. It’s actually needed. The full code will show the rpm and load the motor is at when it’s miss firing.

#10

I can ask for the full vagcom. I don’t know what you mean about the intake manifold being updated, however it was replaced in the summer.

#11

If they replaced it with a new one then it most likely is the revised version. If you have the paperwork, check the part number. The revised one ends with ‘M’

#12

I was getting P0308 misfires only at WOT (>4000RPM) - likely when the intake manifold flaps opened. I took the following steps that seems to have fixed it. YMMV

  • replaced cracked oil feed tube (to oil separator)
  • resealed valve cover gaskets (prevent oil leaks into plug/coil packs)
  • swapped coil pack & plugs for cyl 7/8
  • 1 bottle of G17 fuel additive + 1000 miles of driving before the misfires stopped

The misfires are gone, but I think I still have a carbon problem because I get occasional stuck IM flaps when I start the car in sub-zero weather.

#13

So I had unrelenting misfires with my B7 A4 only to have the same exact issue with my C6 S6! So many similarities it’s uncanny.

Always happens on mid throttle acceleration, kind of a stumble when trying to pass. Doesn’t seem to happen at low throttle or at WOT, but definitely feel loss of power. Just bought the car, knowing it had misfires but the price I paid was reflective of that knowledge.

I had the valve cover gaskets replaced, new plugs, a thorough decarb, and a new oil pan gasket. I hoped the decarb would take care of the misfires but I am still throwing codes 0300, 0304, 0309. This is good because prior to decarb, it would throw codes from more cylinders, but now it is confined to 4 and 9.

I’ve been running different kinds of fuel additives from day 1 and it hasn’t made a noticeable difference. I’ve used Marvel’s Mystery Oil for 3 tankfulls, and Audi G17 for one. I also swapped out the coil pack from 4 to 1 and still getting misfires on 4.

At this point I’m pretty sure I need a fuel injector or 2, but hoping something easier pops up. I should note that the previous owner took it to an Audi dealer which recommended a decarb and 10 injectors but he wasn’t parting with $3000.

#14

So it seems like a can of SeaFoam on a half a tank of gas has fixed my misfires!

No CELs all afternoon. It’s still not 100% but we are getting there. I just filled up the tank and added Royal Purple Max Fuel System cleaner as I’ve read great things about it. Hoping it gets smoother and stronger over the next few tanks of gas. I’ll update as necessary.

#15

Interesting. I don’t think I have ever heard of Seafoam curing a misfire problem, so I’m interested to see how long the situation lasts for.

Let us know if the problem returns, or if things are still looking good a few months down the road.

#16

Just to clarify, car was just carbon cleaned. The sea foam probably only cleaned the injectors. Since yesterday only have seen pending codes, and still no cel.

I will definitely keep this updated.

#17

Ah, cool. That makes more sense.

Let us know how it goes.

#18

Yeah, my car is still misfiring. My guess is it’s the fuel injectors as well. I think the rest of mine are being replaced next week, that’s literally the only thing left that would cause a misfire.

#19

Please keep us posted Irish. Since you have provided so much info on your case, it would be great to be able to identify root cause(s) of all your issues so that they can be included in the Info Dump.

#20

Well, I may have spoken too soon as they’re not completely gone, but much, much improved. Gonna keep cleaning the injectors via the fuel for now, but I expect that I need new injectors for cylinders 4 and 9 as they keep throwing pending codes. However I’ve gone from throwing codes on every pull from multiple cylinders to a consistent code only from 4 with 9 only throwing pending codes. And there are zero or less than 10 misfires from the other cylinders when I’ve checked.

Carbon clean, new plugs and valve cover gaskets get the majority of the thanks with Seafoam the rest. I still haven’t changed coil packs, but swapping 4 with 1 didn’t yield any changes.