2008 s6 misfire *2nd post attempt* (first didnt go through)

A6 All/ S6 All
#1

Hi everybody. My name is Jon, Ive owned my 2008 v10 s6 for about 3 years. I love it. Recently started misfiring out of no where. Couldnt even idle or drive anywhere. ran codes got multiple misfire code. Changed all the coils and spark plugs. same misfire ( although it I felt like it ran alittle bit better but close to the same misfire). ran codes again. the camhaft senosr code popped up. changed both sides and still the same.

At this point i figured the injectors where dirty and the carbon build up was causing all this. took off intake. doesnt look as bad as i thought it would in the intake ports. removing and cleaned all injectors with the carb cleaner can adapter and battery cable kit( fires the injector when connected to a power source)

BUT…
After very close inspection of the valve port area. One of my valves is stuck open by a broken piece of plastic or metal ( looks more like plastic). I wish i knew where it came from. Ive been trying to pry it out but its stuck in there pretty tight.

So, my question to anybody that has experience is. Could I just carefully grind it or cut it out( i know some of the pieces will fall down in the motor bit will be using a shop vac while doing the grinding to catch most of it.

So, on that port that valve is stuck open and the other one is closed. to my knowledge they are both supposed to be in the same position (both open or closed) since all the other port valves are. so, after removing the piece, will the valve go back to its normal position( releasing the tension on the valve spring) or am I just screwed and I gotta remove the whole head and replace the valve? it does not look bent…

This is my first post on here. so any help will be much appreciated. this has been a nightmare for me.
thank ya’ll

-JoN-

#2

tried to upload the pic but it keeps saying " upload file full"

#3

I uploaded the pic on “my media” in my profile. click on pictures and “2008 audi s6 stuck open valve”.

#4

to make things easier here is the link:
http://audirevolution.net/view-image/1861/2008-audi-s6-valve-stuck-open

#5

The picture is quite blurry. What color is that piece of plastic? It may be part of one of the pivot brackets out of your intake manifold. When one of mine let go, it rattled around inside the intake for a while and then the noise stopped. When I pulled the manifold off, there was quite a large piece of plastic sitting down in the intake port right next to the valves.

I would rotate the engine by hand till you get the valves to open fully. Then see if you can pull the piece out with the valve spring pressure off of it.

#6

my thought was a piece from the IM as well.

with a piece of plastic jammed between the valve and the block, is there a risk of damage to the valve? i’d be worried that it couldn’t function properly anymore (but honestly i don’t have a feel for it)

#7

I just went through this. Just finished putting the car back together. Pull the valve cover and inspect the rocker on that valve. I had the rocker pop off. but also the exhaust cam spin.

#8

When the weather temp drops the car kicks on the SAI system and the cold start regimin that itself will cause the car to run rough. Even a good maintenance car will run a bit rough in cold weather.

The injectors are going to need cleaning no matter what. They go bad and get to the point where misfires are common place cold or warm.

That being said the intake manifolds are one more spot that has issues and will result in a broken intake. The black plastic air ports in the intake over time brake off and its common to see them in the cylinder head track.

At this point I would take apart your intake manifold and inspect the manifold inside to see the current condition. There is a video on here on how to do that.

#9

wow small world huh? Im happy you shared and glad you told me to check the rocker. was the plastic stuck in your valve too and was it causing it to misfire?

#10

thanks so much for your response. how do i rotate engine by hand? do i need to remove bumper?

#11
#12

I would put the lock carrier into the “service” position to give yourself some wrenching room between the crank pulley and the rad fans. Part of the procedure is removing the bumper cover.

#13

Yes! I had a piece of intake manifold plastic holding the valve open. But when i pulled the valve cover i had damage not saying you will though. Also you need a special socket to spin the motor by hand.
https://uploads.tapatalk-cdn.com/20181008/40a9f7a03bc70eb58737b5672d0a54dd.jpg

#14

You will want to remove the bumper. Pull out the bolts in the front core support and pull back the core support or fully remove it. Once you have done that you can get a 24mm socket on the alternator nut and spin the motor that way. Keep in mind if you don’t pull out the spark plugs your going to be trying to spin over a motor that’s coming on compression. To make spinning the motor over easier pull out the spark plugs.

#15

hey bro i gotta question. i spun the motor by hand but that single valve with the plastic stuck in it will not move. all the other valves move. so i got a soldering iron and screwdriver and melted it and dug it out. Im sure alittle bit dropped onto the bottom end (hopefully it will just melt and pass thru the engine through the oil and i could drain that oil and put fresh oil.)

anyways, once i removed the plastic it relieved the tension and snapped back down. but still wont move like all the others. So, i think im in your boat. the rocker popped off or something else is wrong. im going to remove the valve cover, but i also wanted your input on how you repaired yours.

Thank you,
JoN

#16

hey how did you put the rocker back on? Mine popped off like yours and was sitting in the bottom of the head.

#17

Hey where can I find the gasket inbetween the intake housing? I don’t think using the same one would be a good idea.

#18

07L 133 075 A

Check your topic specific thread for picture.