HouTex

Our A4 has about 64,000 miles and last week it started to experience a slightly rough idle. It was noticeable but did not seem like it was a huge issue. At cruising speeds the engine seems to perform very well. But at idle it seemed to be misfiring on one cylinder. Took it to the dealer and they tested the obvious (spark plugs, coils, etc.) and they thought it was the injectors (it was throwing a misfire code on cylinder 2; but the engine light was not on) and they quoted me around $1,800 to replace them (all out of warranty). I had my indy replace them for $1,000, but it still has the same issue.

Took it back to the dealer and now they say some "baffle" has come loose under the oil cap and it has, somehow, fallen into the engine and been "banging around" and it has caused an unknown amount of damage. None of that is apparent from how the engine has been running--again, at cruising speeds the engine seems completely fine. They won't know the extent of the damage until they take the engine apart so they can't give me an estimate. They want around $1,700 just to do the work to determine what the full extend of the damage is. They say the repair could be $7,500 or even more. They think, but can't be sure, that the exhaust cam and another cam need to be replaced.

I'm having the car towed to an indy for a second opinion. When I called the indy he didn't think it was possible for the baffle to come loose and do extensive damage. Any ideas?

SMac770

Did the dealership show you this visual evidence upon which they are basing their story?

"Seemed to be misfiring on one cylinder". This isn't the kind of thing you guess at. Hook up VCDS, pull DTCs, know what's actually going on.
A misfire DTC without a MIL light likely means it's an unconfirmed DTC, which means it's not repeated itself.

Any instance of rough idle for me has been the PCV. But you'll see random misfire codes for all four cylinders, and you'll notice the roughness smooth out if you remove the oil cap. Also normally comes with a freight train whistle sound.

I'm sure there's a better process of reviewing engine data to push a direction of investigation for a "rough idle", but thankfully, I'm not an auto mechanic.

HouTex

"Seems to be misfiring" was my thought based on what I was feeling. The dealer said it was throwing intermittent misfire codes for cylinder number 2. When I picked up the car today they unscrewed the oil filler cap and they showed me that the baffle is gone. The car is now at any indy and I'm waiting for a second opinion. Thanks for the reply.

SMac770

Is this baffle something on the oil cap itself, or the metal piece that is inside the head that is right under the oil cap? Ie, the metal that the oil lands on when you pour oil in.

Ie, the shiny metal piece visible in pics 2 and 3 of this listing, http://www.ebay.com/p/Audi-A4-B8-06H...4125787&chn=ps

HouTex

It's the latter. I've seen a couple of DIY oil change videos on Youtube on the 2011 (slightly different than the 2013) and there is some kind of metal fixture that is attached to the engine housing (if that's the correct term) that is visible when you remove the cap. That piece is now missing and I can see into the engine.

SMac770

Yeah, I updated my post with a link to an ebay listing for a cylinder head cover showing the metal piece I believe you are talking about, in case you didn't see that update.
That came loose and is rattling around inside the cylinder head. Damn. I'd be pissed and having a chat with AoA. That kind of repair scenario at 64k is not good for repeat business.

That said, looking around caused me to run across a new video from Charles the Humble Mechanic. Tears down a CAEB motor (old tensioner, so guessing 2009 or 2010) with good video quality.

HouTex

Yes, that's the piece. The dealer is claiming that the indy that did my oil change must have broken it off during the oil change. The oil was changed recently--a week or so before the symptoms developed.

SMac770

That sucks. Now it's a he said she said, and yeah, kind of have to side with their thoughts. That doesn't help you much, seeing that it's sitting at said indy now.
But if it runs fine at cruise, you probably just need to get the head cover off and get it fished out of there and then see what's what. Hopefully it can be fitted back into place. I assume it's purpose is to keep hot oil off the cap.

HouTex

It's with a different indy now. I trust this guy to tell it like it is. We should have gone to him to begin with--that's another story (wasn't my decision). It's just hard to believe that there's serious damage with the engine running so well at cruising speeds and not showing an engine light.

SMac770

Well, you don't know there's any engine damage. Hell, for all you know, that baffle has been missing and your issue is something else entirely.
But you do want to see what's in there, and if the baffle has been bouncing around, then inspect the cams and such. But right now, everything is speculation. I wouldn't drop too much money on speculation.