silverRS4

The restricted flow into the cylinder would be the primary concern. The ridge of buildup on the valve perimeter and the "lump" on the stem are in the worst possible places. I don't think the weight is really an issue. Just how much the airflow and engine performance is hurt is really hard to say.

The distribution of buildup from cylinder to cylinder is fairly even, but if I had to pick based on what I've seen, the rear (2) cylinders on each bank tend to be the worst. These are the two that are closest to the where the cyclone separator is venting the crankcase air into the manifold.

RS4POWER

SilverRS4-

Have you been using Scott's recommendation of RLI 5w-40?
If yes, have you removed the manifold to inspect how the oil performed and what did you find? I also wanted to ask how the new nitrogen enriched gas from shell v-power would help this problem if at all.
TIA.

jkocher191

adding a water/meth kit prior to the throttle body should keep things clean

ArthurPE

capture/reuse the water from the combustion process, there are many gals produced
inject it into the intake
repeat until clean


how much water is produced per gal of fuel burned

silverRS4

RS4Power -
I’ll try to get the whole history as brief as possible. It’s lengthy, but hopefully informative. From the time the car was broken in, the cold starts were frequently rough and power delivery was erratic. The roughness should not be confused with a hunting or oscillating idle. It was caused by misfiring, as verified with Vagcom. It eventually got to the point when there would be 30-40 random misfires in the first 15 seconds. First oil change was at 4k by the dealer. By 8k miles, I had been in twice for “coil” issues to “correct” the CEL’s caused by the misfires. The coils were not the problem. The Service Mgr (not the SA, who was clueless) decided the fuel system should be checked. Four injectors failed the leak-down testing. Upon removing the intake to replace all 8 injectors at 8k miles, they discovered a disturbing amount of buildup on the intake valves. I saw the buildup, but did not take any photos. The dealer did a very good job of cleaning them and with the new injectors, the car ran much, much better. There have been no misfire issues since. I have hooked up Vagcom several times after the car has been sitting for 2-3 days and zero misfires are recorded – the engine fires up nicely, just as it should. The dealer used a fair amount of solvent when they cleaned the valves, so I changed oil at 8k, using the Castrol TXT synthetic available from the dealer. At 9k miles, I swapped in my ported intake. Low and behold, after only 1000 miles on a good 501/502 oil, the intake valve buildup was already at least 1/2 of what it was at 8k. I had figured that with good injectors that were no longer leaking fuel into the cylinders when the engine was off, there would less fuel dilution of the oil, less oil vapor in the crankcase air stream and much less buildup. Apparently not. So I cleaned the valves (major PITA), and decided to start using the RLI 5W-30 oil and fuel conditioner. At this point the car was running very strong. At 11.5k miles, I swapped in my version 2 ported manifold. After 2500 miles on the RLI oil, there was some buildup on the valves, but it was minimal. 500 miles later, I swapped manifolds again and of course the valve condition hadn’t changed much. The buildup rate is definitely slower with the RLI oil. So what have I learned? 1) The high performance nature of the RS4 engine means it volatizes a lot of oil, plain and simple 2) Generally speaking with FSI engines, rough cold starts and misfires are probably injector related – a bad coil would misfire all the time and minor valve buildup apparently doesn’t cause misfires 3) The injector problems are isolated and may be due to a manufacturing tolerance issue 4) I’ve used Tier 1 Shell fuel exclusively, it may keep the fuel system clean, but it does absolutely nothing for intake valve deposits on a FSI engine 4) A good fuel conditioner will help with maintaining clean injectors and minimizing combustion chamber deposits, but with a FSI engine, its affect on the intake valves is minimal 5) Oil chemistry can make a difference with the rate of buildup 6) Even considering the oil volatization of the RS4, there seems to be an abnormal amount of oil in the intake, as if the fine oil separator system is overwhelmed or does not work at all. There is a drain line that lets the separated oil drain back to the oil pan. But it has a simple valve so that it drains only when the pressure on both sides of the valve equalizes. This equalization really only happens when the engine is turned off. One possible scenario here; if the valve doesn’t work, all the oil gets sucked back into the manifold and the separator is doing effectively nothing. This oil vapor is what’s cooking on the valves. With a 3-stage cyclonic separator, you would think that if the system worked, there really would not be such a big problem with oil vapor in the intake. That may be why the separator was changed out on bstellar’s engine. However, the swap looks more like a guess rather than an update. Considering the impact of an updated separator that was intended to correct the build-up problem on a FSI engine, you’d think there would be a recall or at least a TSB. That does not seem to be the case.

The G Man

Nice write up SilverRS4, it seem like this carbon built up issue is starting to spread to other other models as well. Did Audi change something with their valve timing in the 07 to 09 FSI engines? It seems like only the newer Audi have this problem.

greatwhiteshark

Great post silver.. I/we appreciate the time you've taken to document your experience, which seems more of an inevitability for the rest of us the more I read about it.

I was wondering if the Q7's 4.2 FSI motor is exhibiting similar symptoms due to the similar design of the engine, but upon further investigation it looks as though the two engines differ in the way the oil settles back into the crankcase. I asked my dealer if they had any 4.2 FSIs in for carbon/oil/valve issues and he said only for the RS4 and R8 so far. There are probably 5x the number of Q7s 4.2s in service compared to the RS4/R8s, so I wonder if the problem is limited to ours, or just not realized by the Q7 owners for one reason or another.

-Matt

greatwhiteshark

I'm particularly curious (per the second attached doc above) about the following:

1 - 'piston ring flutter at high engine speeds and low engine loads can result in a very high gas-flow rate.' what does that mean...revving the engine at a standstill?

2 - 'when the bypass valve opens, a fraction of the blow-by flows to the engine untreated, but the remainder is treated optimally by the cyclones.' is this 'fraction' the stuff that's settling on the valves?

bstellar

It's not just the high-revving 4.2 in the RS4 and R8. There have been numerous posts on forums regarding the 2.0 TFSI having deposit build-ups on the intake valves. My service advisor has also had 2 5.2 V10s from an S6 and S8 that have needed walnut blasting to remove intake valve deposits.

The high-output nature of these engines and their gas recycling systems might be an exasperating factor. As i've posted earlier, i also own a 2007 Touareg with the newer 3.6 FSI engine that has been strong and trouble free for over 32,000 kms to date. I'd love to see what the intake valves on it look like.

The G Man

My dealer told me that they did 2 carbon cleaning thos month on 2 08 A6 3.2L, so its not just the high output engines that have this problem. The tech pointed out that this is a problem on the A6 during the break in period. Reading the doc above, I wonder if the oil cyclone system having a problem with the break in oil Audi uses. Generally, break in oil is thinner and lighter, in theory, a cyclone seperator should be less effective with a lighter oil weight.

What do you guys think of that theory?