You can buy them! $49k USD for the headers, and get the rest of the car for free 
I’ll have to pass for now lol…
that’s almost as good an offer as $20k for an RS6 bodykit…
Any hope to sort the misfire before summer rears its head? Crossing my fingers for you! I have listened to your video several times and the headerback exhaust is just epic. Can only imagine this once dialed powerplant wise as you have most of the other stuff in place except for a few LW parts to make this a tru goon and riot to drive!
Thank goodness for your pioneering and people investing time and money in the platform! Oh and JHM for actually releasing new products!
Thanks vtgt. Still working to get it 100% Right now I’m driving it daily with no major issues. But, obviously I’m not done with it until everything is resolved.
I have this and another project car on the go, so driving this one now while the other is in the shop. Then, when its ready in a couple months Ill switch back, and the S6 will go in for the final work. Nothing moves quickly when you are doing extensive modifications.
Yup right there with you. I’ve got a few things brewing project wise too, excited to see how they turn out! Hoping to do an intro thread soon!
Glad it’s working well for you even if not 100% I know that the p-cars can be high maint too! But the final products are beautiful aren’t they!
Just don’t get too bored once they are done. It’s quite an addicting slope right !
Well, wish I had better news, but over three years and tens of thousands of dollars now into this car, and it still runs like crap, way worse than the day we started. I have constant misfires, despite replacing pretty much every part around the engine with brand new stuff. I havent been able to get the plate sticker renewed since Jan 2016, due to the contant misfires which result in a check engine light.
Looks amazing sitting in the driveway though. Would be nice if it would run right.
IT does look fantastic. These cars seem plagued with misfires in almost every situation. If I knew all of what you changed I would be happy to try and help give you direction. Obviously there is something lurking still. If I can help let me know.
Very sorry to hear.
What are the plans at this point?
Since the lambda values look wacky, we’re going to replace all O2s with new units.
Fingers crossed!
It seems almost weekly we are making strides in getting to the bottom of all the possible misfire issues that come with these cars. If you are having lambda issues that is usually the bassis for all misfires.
If you haven’t start from the back of the car to the front.
So far we have seen misfires issues that come from.
fuel filter as that hoses the FPR
The HPFP on the cylinder heads
and in some cases the LPFP can be weak
Usually the fuel related misfires flair up after you drive and come to a stop. Part throttle the cars seem ok but when you come to a stop or take off at low rpm from a stop the car can’t regulate fuel and you get lean misfires.
changing the 02s is a great place to start as these cars don’t seem to get 02 codes as easy as the other cars but changing the 02s fixes a lot of issues on the RS4s and the other FSI motors. I would think on how hard the 02s are to change on these cars that Audi probably sets the trigger very high so its possible to have a bad 02. Usually you can spot bad 02s and fuel issues in a log. You can see the 02 voltages drop off.
Let us know how it turns out.
Thanks for the advice Justin, as always.
The o2s are the next logical step, at this point. At the same time, it is still just a guess.
I guess what makes troubleshooting tricky (and sometimes exhausting) on these cars is the lack of clear guidance from the ECU. I am going to replace all o2s, which will be about a thousand USD plus labor, but I have no o2 error codes. And, I am lucky, as we moved all the o2s during the headers/exhaust fabrication, so labor costs will be minimized. If it was stock you would have to drop the engine. At the dealer, I am guessing this is a $4000 to $5000 job. And with no clear indication to tell you if you should do it, or not, you are just expected to take a gamble and hope for the best.
Everything is expensive on these cars, in regard to both labor and parts. When misfires started showing up on the v10 S6s way before warranty expired, did Audi simply provide an ECU update that hid the issues? I have one bank at 25% positive and one bank at %25 negative (maxed out) on the partial fuel trims, but still no error directly related to that. In the past S6s, you would have one for sure.
Its no wonder that misfires are so hard to track down on these cars, as the ECU does not give the usual guidance, in regards to error codes. Nevermind, that there are two ECUs, and the measuring blocks in VCDS are not in the places where you expect them to be.
Ill have to admit, this car has pushed me way past the point where I was having fun with the project. I have to get it fixed, because otherwise it is worthless. But, if I could go back three years and start all over, I wouldnt go anywhere near this car. I am probably in for about $50k CAD total now, and up here in Canada, that can buy a respectable automobile (e.g. 2013 S6 with 80k km.). Meanwhile, I have a car sitting in the driveway that is barely driveable, and still needs an undetermined amount of more $$$ to get fixed, if it will ever be fixed.
you hit the nail on the head. Audi mandated an ECU flash on all the v10 4 bank motors. You can see it in the Carfax reports. things that you would see error faults for like you mentioned fuel adaption values and 02 lag codes are way delayed for some reason on the 4 bank V10 motors. It seems every since carbon misfires started showing up in the RS4s that audi ECU updates changed how the car sees misfires and reacts to them.
I’m trying to put together a misfire track down thread because there is at least one post a week about guys trying to track down misfires. I don’t know how often you read whats been going on here but the fix formula for misfires for new owners seems to be new injectors new intake or a solid reseal new PCV system new check valves and make sure the LPFP and HPFP are in good working order.
Your 02 idea is smart money because almost all the time if you have a stock 02 sensor with more then 80k and you put a catback exhaust system on the car you typically see the rear 02s go bad and the same if you remove the cats you see the front 02s go bad. You don’t always get a code but you see it in how the car runs.
keep us posted.
I agree with this statement 100%. I will probably catch a lot of crap for saying this, but I’m starting to second guess myself with this car. The overall costs associated with running it and the potential performance to be had out of the 5.2 is questionable, at best. I have an M6 that is head and shoulders above it in terms of performance and has been a lot easier (and cheaper) to maintain over the 5 or 6 years that I’ve owned it. But at the end of the day it was my choice to buy the car and it’s up to me to make it right. (Whatever that might be!)
I’m (almost) in the same boat as you… I bought the car for around 15k USD and have put in roughly 4k in this first year of ownership and still have similar issues as you, albeit no misfires. I’ve had some exhaust work done to fix leaking flex pipes, addressed a few vacuum leaks, changed coils and plugs,
did the carbon cleaning on the intake valves, replaced the intake manifold because some flaps were broken,
replaced the fuel injectors and did brakes and rotors all around. I’ve been documenting my journey in this thread for about a year now, trying to track down lean/rich issues on bank 2 (cylinders 4 and 5).
My theory is that the bank 2 rear o2 sensor is lazy and does not recover quick enough from when they essentially stop reading during de-acceleration (IE coasting at above ~35mph when the injectors essentially stop). When that happens, it’s telling the ECU to dump in more fuel because it’s picking up too much unburnt oxygen in the system past the cat. From there, it dumps in more fuel and since the rear o2 is still “lazy” the upstream o2 picks up the decreased amount of oxygen present and sets a too rich code. This condition more than likely forces the car to ignore the long term fuel trims both at idle and partial and only relies on the short term fuel trim from bank 2, sensor 1 to adjust the injector pulse widths on cylinders 4 and 5.
This would confirm that, to a certain extent, the post cat o2 sensors on these cars contribute to a certain degree fuel trim data to the ECU.
In fact, when logging the output from both passenger side post cat o2 sensors, you can clearly see that bank 2 is slower to recover than bank 1, and in some instances at idle it is around .25 volts. I even smoke tested the exhaust on that side and nothing turned up.
If anyone wants the logs from VCDS let me know, I can post them up.
In your case, I think you’re dead right. Audi or someone else got fed up with getting CELs all the time and just changed the tolerances on the ECU to account for the shitty post cat o2 sensors.
So like you, I am stuck between a rock and a hard place. Do I bite the bullet and spend two or three weekends pulling this engine to replace one silly o2 sensor or do I off load this thing on some poor unsuspecting 22 year old kid who’s looking for a flashy car that happens to have around 15k sitting around?
It’s my belief that you have to budget ~$3k/year for maintenance for the LIFE of this car. In my opinion, this is an outrageous cost of ownership, but I think it’s a reasonable estimate based upon my 3 1/2 years with the car and following this and other boards.
My ONLY reasons for sticking with it are threefold: 1) putting cost aside, I still like driving this car every day and there are no other cars I want, 2) I have decided to do all work myself (but, of course, couldn’t handle an engine drop, for example), and 3) the value of the car is at rock bottom. I’m not saying I expect the value to go up, but buying another car (new or used) would bring a lot of depreciation with it. That cost has to be factored in to reasonableness of the maintenance costs for this car.
When I was dealing with my misfires a while back for A YEAR AND A HALF, I wanted to set the car on fire and then drive it off of a cliff. But like every S6 owner recognizes, you then own an unsaleable car that you’re better off fixing. So, you fix it and then remember you enjoy driving it. And, so the love/hate cycle continues…
There is absolutely no getting around the FACT that this is an expensive car to own. To any sane person, owning this car long term defies logic. There are fast and cheaper performance cars to own. The real problem is that once this car has it’s money-draining hooks in you, it’s hard to shake for a variety of reasons.
As an aside, the main reason I avoid any mods to this car is that I believe it is already on the ragged edge. If you merely fart near the engine bay, you might cause a vacuum or oil leak that takes $3k to locate and fix. And when you start putting aftermarket parts on this car, the effects begin to snowball and then no one has a really good understanding of what might happen and it becomes just too expensive to figure out.
I don’t think I’m being negative. I just think this is reality.
well this thread took a turn towards depression…
…with that said, i somewhat understand the maintenance pains… I’m about uhhhh maybe $10k in… but like was also said earlier, i don’t want another car (can only be but so fast in a 4-door… on public roads…) and after the JHM treatment it’s even harder to accept the possibility of ever trading it… so, for now, we pray…
(and i just picked up my car today after HPFPs were swapped)
haha, sorry, that wasn’t my intent. ;D
I guess my overarching point is about setting your expectations.
Carry on with the thread. :-[
[quote=“Nebuchadnezzar,post:314,topic:6819”]
I think you may just have amazing luck… I’ve heard many horror stories about the fragility of the BMW V10 motors. Maybe the horror stories seem plentiful because they’re the ones that get published online…
honestly if you really look at how far this community has come over the past few years I think the light at the end of the tunnel is closer for everyone. Just years ago people were spending way more money with no results to fix simple issues that we all now know how to fix and there was no performance possibility for these cars.
We have a lot of documentation going on here and the cars have gone from very depressing 14second maintenance whores to 12second contenders with better fuel mileage and a possible future for real performance with a solid issue free running car.
I have been looking for an S6 for myself for a while now and the theme I keep seeing is all these cars unless your on this forum are lacking an all the needed maintenance. People just don’t know what these cars need. There is a preset of things that need to be replaced every so often and if the owner before you didn’t do it you are going to have to do it. The more miles you get on the car the more things you need to replace BUT ONCE that is done. You have a solid car for another 100k
Coming together as a community to share our tricks and results just helps us all get to the misfire free power place that much sooner.
That’s my attempt at shedding a little light on all this.
Well, I dont want to jump the gun, but I have a much more positive update.
When I had the car over the winter, disconnecting the MAFs seemed to make it run much better. However, last time I had the car for a day a month ago, and it started to misfire like crazy on the highway, I pulled over and pulled the MAFs and it seemed to make it worse, and definitely wasnt any better.
Today, I got to thinking, maybe I have to clear both ECUs after disconnecting the MAFs, so that NOTHING is saved in the learned memory, and it would just use the default maps. So, I did just that, and now the car has never run better. Lots of power, a million times smoother, and no misfires that I could feel/hear. It was like night and day.
So, as of now, everything is pointing at the o2s, which is what we planned to do next anyway. And, another o2 error code popped up prior to clearing the codes, so just more evidence that we are on the right track.
Here is hoping that the next update is another positive one!