A week ago my 2002 A4 Quattro 3.0L was idling rough at the startup(cold upstate NY weather) and I had been smelling gas at start too. Took it to the shop, they said nothing was wrong. 2 days later CEL came on with multiple misfires and misfire at cylinder 6. Car continued to start with rough idle but rode fine. Another 2 days later the idle got so rough and continued into my ride that I could no longer drive it. I then took out all of the coils on one side, ohmed them and they were all working fine. I then went to the spark plugs and none of them met expectations, so I decided to replace all of the spark plugs. When I got to the other side( which is the side that cylinder 6 is actually on, I started on the wrong side), I came to find all 3 cylinders full of oil. I replaced all coils and spark plugs on this side, after cleaning out all of the oil, hoping I could at least get the car running to get it to the shop. The rough idle got worse and the car stalled, with the ESP light and CEL flashing. I have no idea where to go from here. Any suggestions?

 

Oil in the cylinders? A lot or just enough oil on the plugs to foul them out? If that is the case it's sucking it though the intake from the PCV system. When I pulled the intake off my 4.2 this summer when doing the cam chain tensioners, there was a LOT of oil resting in the bottom of it because it tipped over to one side and ran all over the bench when I wasn't looking. I've had to replace two PCV valves on the thing prior to that and oil simply takes centuries to evaporate. So it could be you have a lot of oil pooled into the intake and it's starting to get pulled into that side of the engine. I just left intake sitting a few days in a big pan to let it drain out while I was reassembling the cams and timing belt.

I'd recommend pulling the intake off and seeing if a LOT of oil doesn't come out. If so, you're PCV valve is probably bad and putting excessive vacuum on the engine crankcase and sucking a oil into the intake at a rate that causes it to pool to the point to where it starts to get sucked into the cylinders at a rate that fouls the plugs. Number 6 cylinder is at the back of the engine so under acceleration, the oil will slosh to the back of the intake. The number 6 runner is probably last in line and will more than likely suck up oil first causing it to be the first cylinder to misfire due to fouling. The runners for that side of the engine may also be positioned in a manner that makes them more likely to suck any pooled oil before the other side, so they will more susceptible to fouling out.

Once you get it running, at idle, try to remove the oil filler cap. Pull it up slowly and if you feel it being sucked back onto the valve cover, the PCV Valve has failed allowing excessive vacuum on the crank case at idle. You will usually get a Lean OBD error code when this occurs though.

 

I would also suggest PCV valve as well as checking ALL VACUUM lines, there must be a leak somewhere, in my personal experience. I would also add to clean and perform a throttle body alignment. Keep back in touch if you solve.

 

If the PVC has been leaking for an extended amount of time, it will suck a LOT of oil into the take and pool in the bottom of the intake like mine did. The way the intakes are made (low spots) in these cars will allow for that to happen.

 

The following are your codes:
P0421-Warm up Catalyst Bank 1: Efficiency Below Threshold.
P0431- Warm up Catalyst Bank 2: Efficiency below threshold
P0442-EVAP Emission Control System. Small Leak

Rosstech suggest a possible firmware update for the vehicle.
The other thing to consider is the catalytic converter could be faulty. I know you can test the sensor at the catalytic converter with the right scan tools- I'm not sure of the procedure with the Audi or this engine but I just performed this check on a Cadillac DTS a couple days ago, I was able to test the sensors before and after the catalytic converter and had base numbers to compare those too to help determine a faulty catalytic converter.

 

Also I'm not 100% sure but your EVAP System could be leaking and throwing the other two codes because of the EVAP code. I know the most common reason for the EVAP CODE is the gas cap not being properly closed. CHECK YOUR GAS CAP!

 

Sorry about those post, I was using my cellphone and those were meant for another member, the forum must not be applicable with my cellphone for some reason.

But have you pulled the valve cover off? Most likely need to replace the gaskets, regardless if your pulling the valve cover off to even get a better idea of what's going on, they should be replaced as well.

 

Thank you all for the feedback. I replaced the the valve cover gasket on the side that was leaking oil, along with all coils and spark plugs. Then to follow I replaced the entire pcv system along with the breather hoses. I found yellow, frothy oil in the pcv valve when replacing. The replacement worked fine for about a month, but there is now a loud whining sound coming from the valve. It is again filled with frothy oil but the car runs fine for the most part, with an occasional misfire at startup but nothing otherwise. I replaced the oil cap and that made no difference. Could the valve be bad? Or is there an underlying problem causing the valve to fail?
Thanks again.