Let me start by saying that I purchased my 996 C4 in November and have driven it about 4k miles since then... it now has 98k on the clock. It doesn't leak and I've had no issues with it up until now.

I recently went away for 10 days and left the keys to the person that was watching the house while I was away. I knew it would probably be driven.. and possibly hard... while I was gone. The person has driven it before and owns an 04 Turbo so I wasn't too worried.

So, fast forward to today... start the car up and it was a little louder then normal and felt slightly rough. I didn't think anything of it. Drove about a mile and the CEL came on and the car began to lose power and run really rough.

I pulled into a parking lot and let the car idle. The CEL went off and the car idled just fine. Go to drive it again and the CEL began flashing and it was rough. As I drove back home, the CEL only flashed if I took it above 3-4k RPM so I stayed below it.

Turned it off in my garage and let it sit a minute. When I turned it back on, I got a bunch of (what I believe was white-ish gray) smoke out of the passenger side tail pipe. CEL was solid but the car was running.

...................

I purchased an Actron CP9580. It fired right up and gave me 6 codes.

P0159 - Aging of Oxygen Sensor After Catalytic Converter (Cylinders 4 - 6)

P1118 - Oxygen Sensor Heating After TWC, Bank 2 – Below Limit

P0300 - Misfire Damaging to Catalytic Converter

P0301 - Misfire, Cylinder 1, Damaging to Catalytic Converter

P0302 - Misfire, Cylinder 2, Damaging to Catalytic Converter

P0305 - Misfire, Cylinder 5, Damaging to Catalytic Converter

The car starts right up and runs with a decent idle... slightly rough but not even close to dying. After about a min there was a slight bit of smoke from the passenger side tail pipe so I shut it off.

...................

So, I drove it out of the garage and over to another bay to get it up on a lift. I had the engine running for less then 2 mins. Again, just before I shut it down, large amounts of smoke were pouring out the passenger side tail pipe.

Up on the lift I could see a bit of oil around the AOS mostly on the bellows.

What worries me the most was a leak coming from the passenger side exhaust at the joint before the tail pipes. It was the color of the oil but had the consistancy of water. There wasn't a ton but it had sporadic drips for a few mins after the engine was off.

I pulled the dip stick and it seemed like it was only oil... kinda hard to tell. The coolant overflow seemed to be 100% coolant .... even tried stirring it up with a screw driver.

Sooooo.... I'm torn here. Could I be on my way by replacing the AOS, spark plugs and tubes, along with O2 sensors and possibly cats? Or, is this a a head gasket or a crack in the cylindar head?

I'm willing to do this first bit of stuff... but dropping the engine and doing head work is beyond what I want to do myself.

...................

So, what do you recommend? I'm looking forward to your replies!

Thanks,

-JRW

 

Sometimes, the slightest thing can cause quite a few codes. Don't panic yet with the rebuilt scenarios... I would start with the O2 sensors. Just take a look and see if they are all plugged in. I wouldn't expect an "after cat" sensor to cause any misfires, but I also would not be surprised. Also, try to track down a Durametric - the explanations for the codes will be different and possibly more detailed than the ones you are getting from the generic reader.

 

sounds like it could be cracked... damn what are they called again....
Ya know those black plastic L shaped units right below the spark plugs...arggg I'm blanking.

Anyway "those" have a tenancy to crack over time or with high temp fluctuation (winter drive 991's).
This happened to me and 3 where actually cracked so bad you could see the copper coil inside and another 2 where cracked at the collar...
Had all 6 replaced (even the one which looked fine) as well as the spark plugs (since you have to remove... these "things" in order to get to the plugs anyway.

I'd start there.
Oh... and perhaps not letting anyone use your ride while you're gone.
Sh#t happens with these older cars, they'll last forever if you treat them right (while still having fun!) but that's dance which comes from the love, respect and passion you've got for your toys, which more than likely will not be shared (to the same degree) by a third party.... better to kick your own @ss than someone else's

Good luck

 

The leak at the exhaust sounds like you got had some water in you pipe and the power issues sound like a sensor problem. Like said above I would not panic at this point. Good luck.

 

What it sounds like is that you need to have it taken to a dealership or shop to have it properly diagnosed. Too many possibilities to chance damaging something by driving it around.

 

[quote=Psycho Sid;3488656]sounds like it could be cracked... damn what are they called again....
Ya know those black plastic L shaped units right below the spark plugs...arggg I'm blanking.

ignition coil pack

 

[quote=FLY996;3489055]THAT'S IT
Knew you'd step up!