Lazydog

Took myS6 into the shop two weeks ago for a check engine light. It came on while going full throttle. Codes came back showing that coil pack for cylinder 4 needed to be replace. SM said that they believe that fixed the problem but should the light come on again to let them know. Totla cost for this service $154.70 I thanked him and scheduled a 75k service for about two week out.

Fast forward to this past Tuesday, I get the CE light again at full throttle. Call up the and they ask me to bring it by on Wednesday. They tell me that they are going to hold onto the car this time to ensure that the problem doesn't re-appear and will give me a loaner and complete the 75k service I had already scheduled for later in the week. So the wife drops off the car on Wednesday and is given a 2012 A4 avant. I have to say I am impressed with this car. Still has got some power and the MPG's are great too.

Wednesday evening I call the SM as I have not heard from him all day. He says I called just as his tech told him the issue was not resolved and the next steps. He tells me that this time the coil pack from cylinder 6 is showing bad and they replaced it but the codes will not go away. He says they want to keep the car another day to run more diags on it to figure out what is causing the codes. I agree.

Thursday the SM calls and tells me that they still cannot get the codes to clear and in order to see what is causing this issue they would like to open her up. I ask what I was looking at right now price wise before they opened her up and he tells me that he was not going to charge me the full price for the diag as it did not fix the problem and we were presently at ~$120. I asked how much this next step would cost and he says ~$600. I tell him to go ahead as I need to get this fixed.

Friday afternoon the SM call me and states they found the problem; "Wow. Cylinder 2-5-9 and 10 were close to carbon closed. I've taken pictures of before/after. I want to replace #6 injector due to carbon damage to the injector nozzle". He also says that he doesn't believe that all that carbon buildup was done by me as he knows I am a spirited driver and use good gas. He believes that previous owner didn't drive the car and run cheap gas though her and those were the causes of my problem. We both knew that the cleaning had to be done so I ask him again were we now stood with the total cost. He says "$1788.90 with the Service.". [=(]

The point I am hoping everyone takes away from this is DO NOT USE CHEAP FUEL!!! The few pennies you save now will cost you double later in repairs. I added the prices so that you can see what you save is not going to cover the cost of repair.

Here are the picture I received from the SM:

We can rebuild her, we have the technology



Picture of the clog



After cleaning

Midwestuser1

It is not the fuel quality as there have been many discussions on the boards about his issue for several years. It is the oil vapors ending up in the intake area and then getting baked on from the heat. This is happening on FSI motors since they are direct injection vs. port injection. Port injection sprays fuel in the intake area and thus the carbon deposits never build up as the fuel acts as a "cleaner". No matter what gas you put in this build up will happen again.

Lazydog

So is there any way to combat this from happening again or am I stuck with going to the shop evey 50k to have this done?

Midwestuser1

From what I've read (I have an 08 A6 3.2 that has the same issue to) there is no way to keep this from happening again. What is NOT known down to the detail is why some cars have it happen sooner than others. See the link below that is dedicated to this issue and that thread started back in 1-6-10. From all of the reading I've done it looks like the harder the car is driven the quicker the deposits will bake on due to more heat (but this is just a theory from the reading I've done). For some reason other will claim that flooring it from time to time helps blow out the carbon but when I asked an smart mechanic about that he said that would just create more heat which is what bakes on the oil vapors.

http://www.audizine.com/forum/showth...gathread/page3

Midwestuser1

If you spend some time reading through the carbon build up mega thready what I noticed is that RS4's got the build up rather quickly and my guess is it gets floored more frequently due to it's performance abilities. That's why my theory is the harder you push the car the quicker the deposits build up to the point to cause CEL's.

SchwarzS6

If you google the problem you can find technical papers from Ford, BMW, GM etc. discussing the problem. One of the papers I downloaded stated that the intermediate heat from running a car easy caused the oil to create a tar like substance because the valves were not hot enough and this partially burned stuff then stuck to the valves. Once the valves got very hot the new deposits would burn and turn to ash. This would indicate that a car which is always run hard would have fewer deposits. To tell you the truth, I am not sure any of the car makers know exactly how to solve or even minimize the problem.

Lazydog

x2 that

Midwestuser1

It is difficult to know if more heat hurts/helps stave off the build up as I'm not smart enough with how engines work to know. What Toyota/Lexus, Now Audi, & Possibly others have done to prevent this is add a secondary port fuel injector that sprays fuel on the valves to keep them clean. Therefore they have direct injection & port injection which I'm guessing slightly lowers fuel economy but that's much better than carbon build up issues.

SchwarzS6

Do you know which engines are using the secondary port injection?

Lazydog

While searching the web I found this interesting post.

Direct injection fouls some early adopters