http://www.audizine.com/forum/showthread.php?t=516237
Weird
Yeah… Not sure I get that one either based on what he is stating… Guess will see when he gets the car back and it’s documented…
Whatever happened to JHM’s 4.2 FSI carbonator?
Threads like that really annoy me. The OP has a different issue than carbon buildup on the intake valves but the morons keep going on and on.
I think they are pulling/dropping the motor to get at his stock exhaust manifolds.
Jimmy…amirite?
Some of the diesel turbo guys would pull their 4 cylinder manifold off and light it in fire to burn off the carbon buildup.
Also, Jimmy, why doesn’t the B8 get carbon buildup the way the other 4.2 FSI cars did? Or 2.0T?> Have they added another injector for a washing function like some of the other OEMs?
Also, what has Audi done on the RS5/RS4 ( B8 ) to combat this, if anything?
Before the charger was installed my carbon was minimal. Of course there was build up but just a light carbon coating at 23k miles
I drive pretty spirited and only put in the best piss grade gas I can find in my area, Shell 91 or CHeveron 91 
Ill tell you what he sends me, but I think I was on the right track…
is that a riddle Jspazz?
Oh sorry, I thought you follow the AZ thread.
“I’ll tell you what he sends me” = He said he would send me a PM with details on the service report.
“on the right track” = my guess is they were cleaning out oil sludge inside the motor.
you guys would make life a lot easier if you just post on AZ…
why would you hold a revolution, only to go back and live under the regime you rebelled against in the first place?
Further, the Audizine thread is about 100 posts long, has run for 2 weeks, and only just now did people start talking about the facts about that car.
I started this thread here yesterday, and the issue was clarified within 5 posts.
I think the question is why would anyone bother with Audizine? Other than the lulz?
http://www.toptiertactics.com/wp-content/uploads/2011/07/lulzsec-lulz.jpg
I laughed coffee out from my nose…thanks
You are right. They have to remove the engine to get the exhaust manifolds off to clean out the secondary air ports because they clog up. Audi did a half ass job drilling the secondary air ports on the 3.2s and 3.0Ts. They drilled out like a 5.5mm hole from the back of the cylinder head that the combi valve bolts to up to front cylinder’s exhaust port. Then they drilled holes into each exhaust port for the pump to blow in hot air for the secondary air injection. Here is a picture to illustrate what I am talking about. The red valve on the back that has an arrow pointing at it would be the combi valve and then the red port goes all the way down to the front cylinder with holes drilled for each exhaust port along the way. Those up and down ports are the ones that clog up with buildup.
http://i284.photobucket.com/albums/ll37/Jimmybones777/Audicylinderhead_zps35c6fc63.jpg
Not my best work with paint but there are very crappy pictures of cylinder heads from what I saw to better illustrate what I am talking about.
Also the spelling errors are getting odder and funnier as I catch on. First it was benefit and now amirite.
I really don’t know why the B8s are getting better with carbon buildup. Toyota still has the patent on the extra injector if I remember correctly. I can only guess that they are using a better crankcase breather setup but that would be a odd change since the 3.0Ts are consuming oil now along with the 2.0Ts. There are two engine systems that Audi has rarely ever been able to do correctly: crankcase breathers and secondary air injection.
The RS5 engine looks to have a similar crankcase breather as the old B7 RS4 V8. If you look at the engine pictures I see two hoses going over the intake pipes to probably a valve that is behind the cover. Hopefully they made a big enough change to not have an issue.
By the way, the 2.0Ts had terrible crankcase breather valves which didn’t help with carbon buildup. I remember replacing those when I first started and they were like revision C or D and when I left there was a new revision P or Q so that is thirteen revisions in a few years.
So this is the same old problem that nailed all e39 M5s (the reason I will never get rid of my check engine light). Carbon buildup in the air injection ports in the heads, which eventually prevented any secondary air flow and tripped the flow sensor. The issue was that the shut-off valves that are supposed to prevent any exhaust flow backwards in the the air injection system leaked, and carbon built up in the passages.
induce the loss of power, though, like norm is describing - just that the emissions during cold-starts will be a little crappy.
Here’s a view of the air injection valves…and crankcase ventilation too.
http://farm9.staticflickr.com/8358/8292500163_4e4be35416_z.jpg
http://farm9.staticflickr.com/8216/8292524275_19cb4e5343_z.jpg
Nice work Jimmy…
I did get the PM from Norm, they cleaned out the air injection ports in the head. It didn’t seem like they replaced any part or looked for any leak, though, which is weird. I would have expected them to at least change a combi valve or something. Looks like they just cleaned it, checked that the pressure sensor showed there was enough flow through the passage, and passed the secondary air test, then handed it over.
Anyhow, this is the only B8 S4 I’ve heard of with the issue, at least so far.
Just to copy my PM exchange with Norm…
thanks to saki and bones
sorry if took some time to get you this over and I appreciate your point of view. Dont spend crazy amount of time but here’s what the workorder points out as to what the technicien noted (translated from french so bare with me and between brackets I’m not sure of the english term so I’ve left it in french);
- Check engin stays on
- Did test for “combie valve” and got 217.62kpa and 145.82kpa with vacuum
- Opened “T.A.C.”
- Drained A/C and Prestone
- Undid electricity
- Removed exhaust
- Removed drive shaft
- Undid suspension components
- Drop motor on work table
- Removed another exhaust component (didn’t define and calls it in french “exhault” which doesnt make sense other than exhaust)
- Removed 2 “combi” valves
- Cleaned passway of the “combi” valves
- Reassembled everything
- Remounted motor
- Filled A/C and Prestone
- Reconnected electricity
- Reconnected driveshaft and exhaust elements
- Reconnected the suspension elements (my Alu and Euro sways + end links)
- Retested “combi” valve and got 146.13kpa and 103.91kpa with vacuum
- Closed everything and did road test
- Aligned the 4 wheels
Hey Norm!
Obviously I was wrong too…you seem to already know this, but anyway:
This is carbon build-up in the secondary air passages inside the head. Air is injected through these passages inside the each cylinder head, with outlets inside each cylinder’s exhaust port, only during the first couple minutes of engine start-up, to feed extra air to the catalytic converter to try to get it to heat up quickly. There is an air pump under the air filter element, it feeds the air through hoses to the “combination” valves at the back of the cylinder heads, near the firewall. If these combination valves don’t seal well, there can be some back-flow from the exhaust ports, and slowly carbon builds up within these air passages.
There are two pressure sensors which detect if the air is flowing properly during this warm-up phase. If the pressure is too high, it will know it’s clogged up and fault out. The “vacuum” they talk about is the vacuum used to actuate the combination valves.
What is weird, is it should not typically lead to a performance loss, though, only emissions will be higher during the first few minutes of warm-up. This is a common problem on cars like my e39 M5, and it seems several higher-mileage Audis from this decade.
I find it strange that they didn’t mention testing the combination valves or anywhere else in the system for leakage, which might have caused the problem in the first place.
Here’s the direct excerpt from the 3.0T self-study guide.
- [i]Testing the system on engines compliant with the ULEV exhaust emission standard (North America)
The California Air Resource Board (CARB) requires that the secondary air system be tested during the heat-up phase of the catalytic converter. However, the oxygen sensors do not reach their operating temperature fast enough for this purpose. This is why a pressure sensor (secondary
air injection sensor -1 G609) is used for making the diagnosis. The “pressure based secondary air diagnostics” function is used.
In this system, the signal from G609 is evaluated in the engine control module. The injected air quantity is determined from the pressure level. Restricted flow, e.g. ingress of dirt into the system downstream of the pressure sensor, causes the pressure level to increase. Restricted flow upstream of the pressure sensor or a leak in the system will cause the pressure level to decrease.
The pressure based secondary air diagnosis process
Phase 0 The control unit is initialized at “ignition On”. The signal from the secondary air injection sensor -1 G609 is saved and compared with the signals
generated by the ambient pressure sensor and the intake manifold pressure sensor.
Phase 1 When the secondary air mass is injected, the pressure in the secondary air system also increases (to approx. 90 mbar). The rise in pressure is determined by secondary air injection sensor -1 G609. The analog signal generated by G609 is evaluated by the engine control module. If it exceeds the set limit value (ex. due to a blockage in the system or a leak), a fault will be generated. If a fault repeats itself, the engine electronics warning lamp will be activated. If no fault occurs during phase 1, the diagnostic process is continued.
Phases 2.1 and 2.2 During these two phases, a secondary air valve (combination valve) is opened and the other valve closed alternately for a short period of time. The values are compared with the value saved in phase 0. Blockages or leaks can be determined for each cylinder bank. Even leaks downstream of the combination valves can be identified from the pressure amplitudes.
Phase 2 During this phase, both combination valves are closed and checked for leaks. This allows evaluation of the secondary air injection sensor -1 G609 value.