RS5 carbon buildup, it's starting...

[superswiss]

So, I have about 17k miles on the ODO and had the check engine light flash a couple of times at cold start. After the first time, they discovered that my car needed an ECM flash that supposedly fixes this. A week later the check engine light flashed again. Took the car in today and just got a call from my SA and apparently I have a little bit of carbon build up in cylinder 6. Audi instructed them to put their special cleaner in the tank and I'm supposed to drive the car hard for the next 50 miles. If this doesn't fix it, the next step I believe is a proper carbon clean.

Even though, I drove the crap out of this car for 4000 miles in Germany, the remaining ~12000 miles here in the US already show signs of carbon buildup. The advise from Audi was to drive the hell out of the car every day. As much as I would like that, law enforcement and traffic around here poses a bit of an issue.

Moral of the story, the RS5 engine isn't immune to carbon buildup!

[Guitarmageddon]

"Special"...."cleaner"....

BG44K....

[Gooner1886]

"Special"...."cleaner"....

BG44K....

Quality product to say the least... But if you have enough carbon buildup for that mileage to get a flashing cel, I'd put money they will need to get their hands dirty rather than dropping some fuel system cleaner in the tank. But they should be doing a complete carbon clean with the other supporting bg products.

[ExhaustNote]

So, I have about 17k miles on the ODO and had the check engine light flash a couple of times at cold start. After the first time, they discovered that my car needed an ECM flash that supposedly fixes this. A week later the check engine light flashed again. Took the car in today and just got a call from my SA and apparently I have a little bit of carbon build up in cylinder 6. Audi instructed them to put their special cleaner in the tank and I'm supposed to drive the car hard for the next 50 miles. If this doesn't fix it, the next step I believe is a proper carbon clean.

Even though, I drove the crap out of this car for 4000 miles in Germany, the remaining ~12000 miles here in the US already show signs of carbon buildup. The advise from Audi was to drive the hell out of the car every day. As much as I would like that, law enforcement and traffic around here poses a bit of an issue.

Moral of the story, the RS5 engine isn't immune to carbon buildup!

I had the same issue with my old S5 and the "special cleaner" didn't do anything. Even if they clean it under warranty (which I had done 3 times on my old S5 at different dealerships in the bay), they don't do a thorough job. Me and and a friend ended up cleaning it ourselves and after we did, the car ran way better than anything the dealers did.

[Tifosi]

That's not good news, especially with only 17K on the dial.

If the build up is on the valves, "special cleaner" is not going to do a darn thing to cure this issue as valve deposit is an inherit design issue with DI system, but I am sure you are already well aware of this. From our previous discussion on AW, I was under the impression that you drive the car fairly hard on a regular bases, which is suppose to minimize the chances of this happening. Hopefully the deposit is on the injectors and you will be tearing down the coast in no time.

[Pilfer]

I think even the 3.0 engines have the same problems. I wish I could drive this car fast but the cops here are brutal.

[Rusty Axle]

The 3.0s have this issue too?

Guess I'll drive mine a bit more agressively then. And also drop a container of Techron in the tank after a fill as well.

I had a BMW that was running rich but with 3 kids never seemed to have time to take it to the shop.

The owner of the shop was very competent, and also had a real knack for finding ways to charge for services.

So when he told me he couldn't believe that he didn't have to do a decarb on my 633, I became a believer in an occasional bottle of Techron.

Haven't used it for years, but sounds like I need to keep some in inventory.

[Ace22]

Silly question...is there any fuel additives that can be added regularly to prevent such a thing now? Hope it goes well with the clean!

[Datadatum]

Given that the fuel doesn't touch the intake manifold, that won't help.

[Ryan_qttro]

Carbon build up on the fuel injector tips in combustion chamber. The fuel additive is to clean the injectors causing misfires. Although you will see build up on intake valves to, it has to get really bad to cause misfires.

[JimWB]

Does driving in sport mode help at all? When in "D" vs "S" my S5 lags a lot more....does this increase the chances of carbon build up?

[yas]

Slow/leisurely drives or short drives where the oil never comes to temp will increase the carbon buildup. Driving hard won't necessarily prevent it, but it sure is fun…

[Racedoc11]

Great ! The way I drive I should be next in the carbon buildup.....If I use the cleaner now would this help eliminating the issue? I have 6500 miles and hardly drive hard.

[superswiss]

I can't be sure yet this is a wider carbon buildup issue with my engine. Prior to them doing the ECM update I had cold start misfires on all cylinders. Now the issue is isolated to just cylinder 6. Audi had them swap the spark plugs and coils, but the issue stayed with cylinder 6. There might be something going on with the injector there and it got gunked up. They didn't say I had buildup on the intake valves. My SA also said earlier that I could have a leaking injector. The leaking fuel during the hot soak period could have caused buildup on the injector tips.

I regularly go for canyon runs and drive the car hard and also do long road trips. Anyway, I took it for an extended canyon run after picking it up from the dealer and got the engine nice and hot. We'll see how it looks when I take it back for retesting.

[ExhaustNote]

Great ! The way I drive I should be next in the carbon buildup.....If I use the cleaner now would this help eliminating the issue? I have 6500 miles and hardly drive hard.

The cleaner does nothing.

[jwm2k3]

Great ! The way I drive I should be next in the carbon buildup.....If I use the cleaner now would this help eliminating the issue? I have 6500 miles and hardly drive hard.

Just give it to me for a week....problem solved :)

[Tifosi]

I can't be sure yet this is a wider carbon buildup issue with my engine. Prior to them doing the ECM update I had cold start misfires on all cylinders. Now the issue is isolated to just cylinder 6. Audi had them swap the spark plugs and coils, but the issue stayed with cylinder 6. There might be something going on with the injector there and it got gunked up. They didn't say I had buildup on the intake valves. My SA also said earlier that I could have a leaking injector. The leaking fuel during the hot soak period could have caused buildup on the injector tips.

I regularly go for canyon runs and drive the car hard and also do long road trips. Anyway, I took it for an extended canyon run after picking it up from the dealer and got the engine nice and hot. We'll see how it looks when I take it back for retesting.

Leaky injector is a good possibility as it is rare these days for the injectors to have carbon build up due normal conditions, especially with additives in fuel these days.

This is probably a dumb question to ask since you seem to know your car stuff, but do you use OTC fuel cleaners such as Techron routinely ?

[Racedoc11]

:) The problem around where I live that cops are all over. You go 5 miles above the speed limits and before you know it they are on your tail.

Just give it to me for a week....problem solved :)

[Raser]

Try taking it to the track every once in a while. That might help.

[superswiss]

Leaky injector is a good possibility as it is rare these days for the injectors to have carbon build up due normal conditions, especially with additives in fuel these days.

This is probably a dumb question to ask since you seem to know your car stuff, but do you use OTC fuel cleaners such as Techron routinely ?

Not so far. I pretty much fill it up with Shell V-Power and if I come by one I get a fill up at a Chevron. I have three Shell stations within spitting distance of my house, but Chevron stations are harder to find.

Try taking it to the track every once in a while. That might help.

Yeah, I want to. So far I've only been able to take it to the Nurburgring while I was in Germany. I wish we had a Nurburgring here. I would have a season pass and go whenever I feel like it. For those of you going regularly in Nor Cal, who are you going with? Seems like the Audi Club only organises a few track events and they have never worked with my schedule. I'm obviously very close to Sonoma Raceway. I know they have some racing schools up there. Any other good option for going more frequently than what the Audi Club organises. Also, do you get track insurance?

[milesed]

Those with build-up,

Did you notice anything in the way it drove before the CEL?

[jauri]

...

:) The problem around where I live that cops are all over. You go 5 miles above the speed limits and before you know it they are on your tail.

[NYSpeedRacer]

One word...Meth

[Jones2012s4]

3.0's barely have an issue. I wouldn't even call it that.

This is at 40,000 miles, lots of short trips and city driving. Probably 50/50 between short trips and 20-30 min jaunts. It's not bad enough to cause any issues. I cleaned it anyways.

Before:



After:

[NOFEARCT]

Even though, I drove the crap out of this car for 4000 miles in Germany, the remaining ~12000 miles here in the US already show signs of carbon buildup. The advise from Audi was to drive the hell out of the car every day. As much as I would like that, law enforcement and traffic around here poses a bit of an issue.

Moral of the story, the RS5 engine isn't immune to carbon buildup!

I had 32k on my car in 15 months. Never an issue with carbon buildup. Let it warm and then redline a few gear changes, it's totally possible to drive the car hard enough on the roads and within the legal limits. I suspect the real risk for the buildup is insufficient use.

[BoostEasy]

All DI engines have some form of carbon build up because no fuel is going over the intake valves and the normal function of the valve guides is to leak small amounts of oil so the guides stay lubed and the valves don't seize up. It's not really EGR etc, it's primarily oil.

If you own a DI car, plan on cleaning the intake ports at some point, depending on the car. I'd be a little surprised and disappointed if my car fouled under 20k miles enough to throw codes. That's BS.

Jones, thanks for reporting your experiences. Your ports don't look too bad at all for 40k.

[GotRS?]

Possibly there's been changes to the engine to reduce this a bit (e.g. faster warm up), but being fairly fresh from the RS4 times I totally expect it, and I guess we'll see more reports. At least cleaning is a cottage industry now if the dealer is awkward.

[superswiss]

I had 32k on my car in 15 months. Never an issue with carbon buildup. Let it warm and then redline a few gear changes, it's totally possible to drive the car hard enough on the roads and within the legal limits. I suspect the real risk for the buildup is insufficient use.

I do that regularly. I have this onramp on my way to the office. I pretty much redline 1st, 2nd and 3rd up that onramp. I'm not going to the office every day and sometimes there's a big rig or another slow driver in front of me, but whenever I can. On top of that I regularly rip through the canyons around here. I just can't do it everyday, but this car does get its exercise more than one day a week. On top of that as I said, this car has seen the 174 mph speed limit regularly during the first 4000 miles I spent in Germany and obviously has been filled with excellent quality fuel during that time, so I'm certainly a bit baffled.

[FaceSmA5h]

The advise from Audi was to drive the hell out of the car every day. As much as I would like that, law enforcement and traffic around here poses a bit of an issue.

Go 45-50 mph on Van Ness Ave! Congrats on ED. Sorry about the build up (one reason I wanted to get out of the 4.2 early).

[superswiss]

Just a quick update. Looks like the Italian tune-up combined with the cleaner cleared whatever was causing the misfires. I'll see how it holds up.

[JamesRS5]

Has anyone thought about using a different oil to try and reduce this issue?

Oil will contaminate the valves in a few ways; a small amount of oil will be transferred on to the valves via the valve stem seals during normal operation and the way they are lubricated, the seals won't remove every trace of oil. Secondly the oil vapor is recirculated back into the engine to meet emissions regulations.

There must be a fully synthetic oil available which is cleaner or contains some sort of detergent to help reduce the build up?

[Jones2012s4]

I believe anything with a low "NOACK" value is what you would want to look for. Noack is essentially a percentage of how much oil is lost when heated to point of vaporization. This would be collected by the oil separator unit(hopefully) if not it will be deposited on the valves.

Even so there are many other ways oil can make it into the valves with or without a proper PCV setup.

Pennzoil Ultra Euro is very good.

http://www.amazon.com/gp/aw/d/B006A49KJC

http://www.pennzoil.com/motor-oil/pe...tic-motor-oil/

[XLR8 Craig]

A fuel additive isn't going to do anything because the fuel isn't being injected into the port, but rather the cylinder itself.

The only completely effective way of removing carbon buildup from the runners, ports and valves is to remove the intake manifold and physically clean them. Seafoam and even commercial chemical-based cleaners do very little if anything to remove the carbon buildup because is is essentially "cooked" onto the metal surfaces. It is kind of like burning something in the oven then expecting that spraying it with some soapy water will remove it from the pan... usually you have to get out the steel-wool.

Here at Excelerate we do quite a few carbon cleanings regularly on VAG cars from 2.0T VW's and A4's to the in-house 4.2 R8 currently getting the cleaning done in preparation for the APR stage III+ supercharger kit install:

[JamesRS5]

I wasn't talking about a fuel cleaner, obviously that will have no effect. I'd be interested in a cleaner oil to prevent the carbon build up, that's the only way you can prevent or reduce the build up, cleaning is as you say, the only effective method of removal.