bstellar

I posted a couple of months ago about recurring misfires on a 2008 RS4. Only 9500 kms on it after 1 year of ownership. Not a daily driver and certainly not babied when i get it out on the highway. After 4 visits and fixes ranging from vacuum lines, to plugs, to coil packs (and 1 DRC repair) i finally pushed hard enough for my local dealer to elevate the issue to Audi technical.

Factory support recommended removing the intake and testing/replacing the injectors. As i suspected, once the manifold was off and the intake valves exposed they called me to let me know that they would have to be cleaned.

I stopped by the dealer this morning with my point and shoot to get some documentation, and it looks like they are using a combination of solvents and walnut shell blasting to clean the valves.

Photos here: http://web.mac.com/braddy/iWeb/Site/RS4%20valves.html

silverRS4

Thanks for posting the pics. I know what its like. Did they have to replace any injectors or did they just test them?

This is going to be far more common than DRC problems. No matter how the car is driven, no matter the Tier 1 fuel, no matter what oil is used, there will be buildup on FSI intake valves.

bstellar

Yes, they are replacing injectors. They have also sent Audi Technical a sample of the deposit material for analysis.

I think we can all agree these problems appear to be widespread with FSI engines. It's even detailed as an issue in VW's patent on direction injection technology. They've simply not gone far enough in reducing the oil dilution and clearing the resulting oil vapor in gas recovery system. My service advisor has told me that they have seen this issue on 2 other 4.2 FSI engines (including an R8) as well as many of the 2.0 TFSI and a single S6 5.2 V10 FSI.

Interestingly, I also own a 2007 Touareg with the 3.6 FSI engine which has been trouble free and never needs oil top-ups between changes. Either it's gas recirculation system is doing a better job or the lower compression and engine design is keeping the dilution and volatility low enough that it's taking longer for the issues to appear. It's now at 31,000 kms.

bstellar

Just got a call from the service advisor. They've completed all the intake port and valve cleaning, replaced the injectors, and have talked to Audi Technical one more time before putting it all back together. Audi has now asked them to replace the cyclonic oil separator with a new one which is now being rush shipped to my dealer. They've also decided to replace a vacuum line on the intake manifold that feeds the tumble flaps according to a TSB, which i recall a few other RS4 owners discussing. Apparently the factory line set-up can become easily kinked so they are replacing it as a preventative measure.

Wondering if this new oil separator could be an updated part. Anyone here know the part number and revision code of the OEM?

STALKIN RS4

Thanks for the update.

WJM

How was it diagnosed or did it manifest itself. Mine is at 22K and I am wondering when this is going to hit (if it has)

How you guys are bringing it to an Audi dealer:
"my car is slow"
"my cel is on"

Help the noob

bstellar

It began idling very rough on cold starts, and would throw the MIL (engine) light. Dealer went went through all the known TSB's (coil-packs, vacuum lines) before finally taking it to Audi Technical (factory) for support.

STALKIN RS4

How does the walnut shell cleaning work, first I have heard of this procedure.

RS Maniac

I recon other solvents wouuld work better than this, just wonder why Audi reverted to this method, they must have some proof it is the most optimal I imagine...

bstellar

They use a combination of both.

They saturate the deposits with a solvent to soften them and then basically sand blast the valves and intake chamber - only they use ground walnut shells as blast media instead of sand. The walnut shells are great at scouring the deposits and absorbing access solvents, but cannot etch the metals. The added benefit is that any shell materials left in the chamber will be easily and harmlessly burned in combustion.

FYI - These deposits aren't flakey and soft as you'd expect. They're almost tar-like and very tenacious. If you look at the photos you can see where they had to take some scrapings from the valve stems to send to Audi for analysis.