Check engine light..again

[esor8]

For the third time in 6000 miles, my check engine light is on. The previous two times were cylinder misfires. Ecu flashed 4k miles ago- thought it fixed misfires. Only use tier one shell premium fuel. The latest misfire occurred in stop and go traffic. Car has rough idle when initially started (not sure if that is a related issue).
Any thoughts?

Jeff
2010 V10 R8

[ianerrid]

As you're in the US, the rough idle can't be the cold start 'run fast/valve open' to me it sounds like a engine problem. It almost sounds like a plug fouling problem, I'd get it checked out by the dealer - they'll hook it up to the diagnostic computer and see if it has had any errors flagged.

Assume you rag it properly?

[KfabR8]

Just for grins, make sure your gas cap is completely seated - turn it one full turn after it clicks. If the cap's not seating fully, it can throw a code.

Rough idle at start up was described in a much earlier post: The monster wakes up, grumbles, farts, scratches it's balls, takes a deep breath and then settles down.

Mine will not wake up on the wrong side of the bed all the time, but when it does, a quick stab of the fun pedal after it's been running for 30 seconds or so (to make sure oil pressure's up and flowing) to about 4K and it's all good from there.

There doesn't seem to be anything that I've been able to correlate between the days that it's grumpy and the day's it's happy when I wake it up.

[MotherTucker]

Sounds very similar to mine. Rough, loud idle at startup when cold (especially since a particular engine software upgrade was done about a year ago), and very occasional misfires. All my misfires were at the track, i.e. when I was running the engine hard and hot. Audi's are known to have a tendency toward carbon buildup, especially those with sports-tuned engines. Occasionally a bit of carbon breaks loose and gets in the valves momentarily and causes the misfire. I use my Vag-Com to check that the CEL is due to a misfire, and then I clear the error code. I've had my car almost 2 years now, and have had 3 misfires.

I talked to the dealer about it, and they actually recommended I run the engine hard and hot to clear out the carbon buildup. They say they have more carbon buildup problems with cars that are always driven very mildly. So they like that I track it. Pretty good

mt

[R84ME]

I talked to the dealer about it, and they actually recommended I run the engine hard and hot to clear out the carbon buildup. They say they have more carbon buildup problems with cars that are always driven very mildly. So they like that I track it. Pretty good
mt

All true! Most people wimp around in town (I'm guilty too!) and the engine just does not get hot enough to keep itself clean. You saw those cherry red exhaust stacks in the R8 production video, right? Smokin' hot!

The same goes for brakes and brake squeal. They can glaze up REAL easy driving around town all the time. The pads & rotors need to realize a few good 70->0 panic stops and a lot of activity to stay clean. I try do this but don't do it as often as I should. My right front consistently runs on the verge of squealing but a few good stops will shut it up.

These cars were designed to run hot and hard, but very few get to.

[TonnyG]

Love the information on this website, I will have to remember to drive my car HARD when I get it.


Tonny

[KfabR8]

Yes, from the moment you put your rear end in the seat.

The engine's broken in as it comes from the factory, so don't worry about bouncing it off the rev limiter "too soon". Just make sure that before you get on the fun pedal that the water AND oil temps are in the operating zone. Oil's temp is probably more important than the water when the car's cold. Make sure it's up.

[toecutter]

Have you done the exhaust mod? I was throwing faults after the rough idle update and they only stopped when I reversed the mod. I can't figure out how it had anything to do with it but it seemed to work.

[r8trackcar]

All true! Most people wimp around in town (I'm guilty too!) and the engine just does not get hot enough to keep itself clean.

Many RS4 (which has essentially the same engine) owners have complained about the carbon build up issue. Just peak into the Rs4 forum in quattroworld. I am not sure I agree that driving the car hard fixes the issue. The real problem is with the design of the FSI engines. Really all of the FSi engines suffer from this issue because there is no washing of valves with fuel to remove the oil, and the inability to keep the oil from getting there in the first place despite a sophisticated catch-can system. For the "most" part, the build up does not cause any misfires. It does however rob the car of 30-40hp! This has been proven with before and after dynos on cars with carbon build up that were cleaned by hand which is a several hour project. Again you can read all about it here:

http://forums.quattroworld.com/rs4b7/

[r8trackcar]

Have you done the exhaust mod? I was throwing faults after the rough idle update and they only stopped when I reversed the mod. I can't figure out how it had anything to do with it but it seemed to work.

Did you have a catback exhaust or did you also have downpipes installed? Usually those fault codes are due to a lack of a primary catalytic converter. The fault you are describing usually occurs when the car is cold, as the primary cat is only used to remove excess emmissions when the car is cold. That is unrelated to a misfire.