Guys i have an update in regards to my misfire/CEL, Both my throttle body gaskets did not have a perfect seal as diagnosed by my audi tech, he replaced the gaskets, adapted everything and cleared the codes, so far the last 3 days driving the CEL is off and the car idles a bit more stable. To check to see if your gaskets are leaking, start the vehicle and spray some soapy water around the throttle body gasket, mine was pretty obvious. hope this helps anyone. the parts cost me about $30.
Great tip, Pat!
;D
In the end, it was the fuel injectors. 6/10 replaced from fidelity, I just sucked it up and paid for the other 4 because the warranty covered all new seals. Heading to pick her up in about an hour. So relieved.
Time to get her up for sale!
Awesome man!!!
If you have the part code for the fuel injectors, that would be awesome. As you know, I am doing my best to squash the belief that the S6 is any more unreliable than any other FSI Audi. And I am pretty sure those same injectors are used on other models outside the v10s.
I know you had a long and frutrating ordeal with the car, but I think that with proper troubleshooting, the fuel injectors should have been identified as root cause much earlier in the investigation. Especially before tearing the engine apart and replacing internal seals, at huge labor cost.
I really appreciate you sharing your entire ordeal. It strongly reinforces my advice to people, that a good mechanic is way more important to have, than an ultra clean car. Every car has its issues, and if the guys fixing them dont know what they’re doing, then it could cost you (or in this case your warranty company) thousands and thousands of dollars.
I know what you are going to answer, but are you REALLY sure you still want to sell the car? You could have had this issue on any Audi.
Nevermind on the part number. This is all the other Audis that use the same injector (06E906036C)
Fuel pump fuel rail injector 5.2ltr. ((A6) Audi A6/Avant
(T8E) 5.2L.
(A8Q) Audi A8/S8 quattro
(T8E) 5.2L.); Fuel rail fuel pump high pressure pump injector air distribution housing 3.2ltr. ((A4Q) Audi A4/S4/Avant quattro
06E 998 907.
(T14) 3.2L.
(A6) Audi A6/Avant
06E 998 907.
(T14) 3.2L.
(AA4C) Audi A4/S4 Cabrio./qu.
06E 998 907.
(T14) 3.2L.)
I have been CEL free for 3 days now. There is still a small hesitation but that has become rarer and rarer. Also, it runs rough when cold. I’ve got it going in Wednesday to check fuel pressure, check to see if the IM is the updated version, check the plugs, and inspect the injectors. Hope to have the warranty cover the major stuff.
With all that said, the car is running as smooth as butter. I used another couple of cans of seafom to a full tank of gas, ran a tank with nothing then a tank with the Lucas fuel system cleaner. But I’m done with the additives for a few tanks as I can’t imagine any more improvement.
V8A6, you said it earlier, and I’ve always considered these fuel additives to be more gimmick than anything, but I’m a changed man. It actually made a huge difference to run quality additives through the fuel. I used SeaFoam, Royal Purple and Lucas, and can say that they all delivered some noticeable difference. That feeling of impending doom(aka throwing a code or hard misfires) is gone and I can enjoy driving again.
Geek, that is some good info.
At some point, I plan to put together a guide for the v10 of all the possible things to check when you are experiencing misfires. Both you and Irish have provided valuable info for the guide.
Please keep me updated on your car. Especially if the misfires return.
Also, I dont know if you ever stated it, did you do a carbon clean? How many miles ago?
Yeah, I got the car walnut blasted about 1000mi ago, was hoping for a car that felt like new only for it to be almost the same. After reading about 55hp changes on the dyno after a carbon clean, I was sorely disappointed. But random misfires on multiple cylinders gave way to just two, then one and now none. Like I stated, it still runs rough when cold, takes a few extra revolutions to start, and there is occasional hesitation when at full throttle, my butt dyno is telling me something is still not 100%, but that’s just being picky. As I spent a pretty penny on a warranty, things like injectors and manifolds and starters and O2 sensors are on high alert. I’m just hoping JHM has the headers available by then so I can do everything when the engine is out!
Carbon is at the root of all these issues. Greek Inc very smart plan to get all the little usual suspects checked out. Let us know how the results are
If you aren’t getting any codes and you are seriously down on power, then I would look at the intake manifold first.
PaulF just replaced his. They are known to have internal issues. I know sometimes the issues come with a symptom of ‘rattling’ sound, but Im not sure if that is always the case.
You may have to take it off and pry it open to know for sure.
Justincredible that o2 sensors can go bad, without giving any codes. With all the cleaning fluids, and the resulting gunk, that has been flushed out of the engine, it is possible that the cats and o2s may have an issue now.
Wait for Justin to comment on that, as I am not the expert on that portion. I only know what he has stated before, but he should be the one who says if it is a real concern or not, and what to look for.
Start with listening to the intake. Talk to PaulF, so see what his symptoms were. I think a bad intake can even cause misfires. His new one totally transformed his car.
And heres Justin! Posted while I was typing my response 
Justin, can you give your Expert opinion on the other items I mentioned?
One thing I noticed when I’m driving late at night when it’s super quiet is a high pitched whine, almost like a turbo diesel that’s chipped. It gets louder when I accelerate, but we’re talking very low throttle, as it gets drowned out fairly quickly.
Not sure what that could be. I’m sure one of the more technical guys will have an idea.
Guys - in regards to the injector -
I am down to my last 9x 06E906036C injectors, and after that I will be out. You may notice them hard to find pretty soon, except from the dealer.
Now, the injector 06E906036F looks exactly the same, and is used in the newer 3.2 FSI. I would really like to know if it will work in the 5.2 FSI, which I suspect it might.
If anyone is interested to help test them, I can send you a set. I can work something out so it would be a great deal (if they do work).
I have been looking into injector flow testing places here in Sydney, but can’t find anyone who will work with the high pressures of FSI as yet.
-P
Does the pitch change when you accelerate, or just the loudness?
Are there any aftermarket electronic devices attached - particularly as relates to audio? Ground loop issues make a whining noise
Low power steering fluid - does it get louder when you turn the wheel?
Alternator bearings going
Other accessory/pulley bearings
That said… the transmission does make a whining noise normally - which is awesome.
Sounds kind of like a Formula-E car noise
Rev in neutral and see if the noise follows. If not, then I wouldn’t worry too much
This! It does sound awesome, unless you think its an air leak! Hahaha!
But I think this is what I’m hearing, reved it in neutral and it didn’t follow. So I got that going for me.
Update: July 15th 2015
Just to bring everyone up to speed…car was carbon cleaned and while there was definite improvement, was still getting some misfires from multiple cylinders. After several tanks of Seafoam, Lucas and Royal Purple fuel system cleaners, I was down to mostly just cylinder 9 misfiring, with a rare #4 throwing a code. Fast forward to about a week ago and a new intake manifold and two new injectors were installed and the car is so much smoother with a BIG difference in push you back in your seat power. However, I’m still getting misfires and misfire codes when the engine is stone cold. Flashing CEL and multiple misfire codes usually when I first got the throttle when I first start up the car after sitting overnight. It happens to a much slighter degree with no flashing CEL after sitting for an hour or two, but nothing as bad as the first start of the day.
Next step is PCV but I’m starting to think that the CAI might be the culprit. I just wish JHM had the software out so I can delete the CAI and cats…
Maybe we’ll see a difference with the PCV valve.
What do you guys think?
My failing battery was causing rough idle at cold start and showing misfires.
Considering the work that has been done could it have been left for a long period with an interior drain that’s depleted the battery?
It could be the PCV system you can have your mechanic test and look at that. With a cold car the missfires seem to come from bad 02 sensors. They wont throw a code because they are not up to temp yet. Try starting the car and if the misfires happen shut the car off start again and see if that gets them to go away.
I think JHM would be able to help with the codes. If your wanting to remove those things and want the JHM tune to remove them contact CV on here and let him know. He will be able to help you