Need Some Advice Here, Please!

[OE24]

I have a 2014 Audi A4 S-Line 6SM. with 46,000 miles

Mods:
APR Stage 2 since 28,000 miles
APR turbo-back exhaust since 14,000 miles
Forged Billet DV since 14,000 miles
R8 Coil Packs since 35,000 miles
NGK R Platinum Spark Plugs gapped to 0.028 35,000 miles

All services have been done by Audi, all oil changes, everything.

Driving home one night from the grocery store, after a long 300 mile trip, car just randomly begins to shake. I was less than a mile away from home, and as I pulled up, CEL started flashing, EPC light was on, thinking to myself, definitely a misfire. So, I ran the codes and got P0303 (Misfire Cylinder 3). I pulled the coils, and then pulled the plugs.

On the plugs there was a little bit of oil on the plug itself, but no broken pieces or anything. I bought new plugs, gapped them to 0.028. Same issue, car is still misfiring. I played with the coils by switching them around and the misfiring still remained in cylinder 3. I then checked resistivity of all coils, and they were all good.

The following day, I have it dropped off at Audi.

I call the following morning, and they said that cylinder 3 has no compression, I need a new engine and that they will not be covering anything due to my tune(this was expected).

Now, my question is...could this really be a mechanical issue, such as a failed piston ring, rod or piston itself? Meaning, could there be some other underlying issue to cause little to no compression in just cylinder 3?
I am getting the car back and taking it home. What else should I check before I tear down the head?

Could it be a clogged fuel injector just for that cylinder?

I am speechless that I need a new motor. I always babied the thing, it is garage kept, I kept up with all services and such. On top of that, I literally drove like 300 miles earlier that day,everything was great, and then go to the grocery store, and out of no where bam.

I must also say, that the car was not blowing any smoke out the tailpipes, just rough idle, and the dash lights (CEL/EPC).

[Longclaw]

At first I would have said it was a faulty coil pack, but if a tech at a reputable audi dealership diagnosed it as something more, I'm not sure now.

Did you try switching around or swapping a new coilpack into cylinder 3? Could you bring it to an indie or another dealershipand see what they say?

[OE24]

Yeah, I did switch the coils around before taking it in, same symptoms though. I must say that when i changed the plugs to new ones. The shaking began to slightly subside, however it was still there. Oh, and the car sounds like a Subaru WRX, upon accelerating.

[Longclaw]

Yeah, I did switch the coils around before taking it in, same symptoms though. I must say that when i changed the plugs to new ones. The shaking began to slightly subside, however it was still there. Oh, and the car sounds like a Subaru WRX, upon accelerating.

Well if you changed them around, the symptoms would have remained, however, the fault code might have given you a different cylinder. If that was the case, then you could diagnose it to be a faulty coil pack. Did you try a new one in that cylinder?

[mortimersnerd]

Was the oil on the plugs just one cylinder or all of them? It's suggests very significant blowby. My first guess would be broken piston ring.

[Pswish]

Compression test in for cylinder 3?

[OE24]

ok, so I took the car back from Audi. They offered an engine replacement for $12,000. I showed them the finger and drove off in my new and improved 3 cylinder TFSI.

I got home, I pulled the plugs and there is no oil on them whatsoever. I played around with the coils and move the plugs around, and it is still an error in cylinder 3. I did compression test, 15 times to ensure I am doing it correctly. All cylinders seem to be around 150 psi, and cylinder 3 is at 35 psi.

I have VAG software and I ran codes again. I got P130a cylinder disabling, and P0303 cylinder 3 misfire. On the way home from Audi, I put gas at Chevron, 93 octane as usual, I am still running APR stage 2 93 octane file. The car began to run a little better but obviously still shakey and the CEL is flashing only when I am at idle.

[OE24]

I am thinking a few different things now:

1) Injector for cylinder 3 is stuck, and lots of carbon fouling on the piston and cylinder walls.
2) Piston ring on cylinder 3 cracked or gone.
3) Is there a bearing on the connecting rod that goes around the camshaft? If so, maybe the bearing is worn out and it is not allowing the piston to move up and down sufficiently due to lack of friction from the torsional motion of camshaft?

My only option now, is if I purchase a new engine and do an engine swap myself.

Do you guys know what engine ID i need? I am assuming it is CAED 2.0T TFSI because it is 2014 A4 with 6 speed manual. Anyway I can confirm this? My scanner shows the VIN and then allows me to select which engine. It is either the CPMB or CAED. tried searching online however information is a bit skewed.

[OE24]

Does this sound like a PCV issue? If so, (this may sound stupid) but where is my PCV?

[mortimersnerd]

Stuck injector won't cause low compression. There is a bearing between the connecting rod and crankshaft, but it's not think enough to do what you're describing. I'm sticking with my broken piston ring guess. Unfortunately, it sounds like it's time for a new engine. Look for a used one in good shape. You'll save a ton, esp if you can install it yourself.

[OE24]

Instead of purchasing a new engine, you wouldn't recommend just buying a new piston (~$200 from ecstuning.com), tearing the engine down, install new piston, and call it a day? Obviously I would do this myself. Not sure how simple this engine is on the inside but i assume it is definitely easier to work on than an X5 4.4 V8.

[Project Quattro]

If you're interested in the low mileage engine swap idea, hit up Lettuce. He did a DIY a year or so ago for a few grand. Good luck with this, man. That's a terrible situation.

[mortimersnerd]

Instead of purchasing a new engine, you wouldn't recommend just buying a new piston (~$200 from ecstuning.com), tearing the engine down, install new piston, and call it a day? Obviously I would do this myself. Not sure how simple this engine is on the inside but i assume it is definitely easier to work on than an X5 4.4 V8.

No. It's likely that there's scoring on the cylinder walls that would require machining. Best bet would be to scope the bore or pull the cylinder head and take a look.

[adamazing]

Stuck injector won't cause low compression. There is a bearing between the connecting rod and crankshaft, but it's not think enough to do what you're describing. I'm sticking with my broken piston ring guess. Unfortunately, it sounds like it's time for a new engine. Look for a used one in good shape. You'll save a ton, esp if you can install it yourself.

You're absolutely right, but a stuck injector could have been the original issue. It could have washed the cylinder walls until they ended up scored - it wouldn't be the first time that's happened to someone here. Just an educated guess though. it still wont fix the issue at this point anymore.

[jfo]

Possibly a burnt exhaust valve? Did they also do a leak down test or just a compression test?

[Militant-Grunt]

I can bet a pretty penny that one of your ring lands broke. It happens, I've replaced a few engines for this reason. Makes sense especially that you had a spark plug covered in oil, the piston is chewing on your block at the moment. I suggest against repair, you'd probably have to overbore at this point, it really depends on what it looks like when you take it apart, though I'm fairly sure the cylinder walls are going to be scored up. If you take your oil pan down (upper and lower) you'll find pieces strewn around.

Are you out of factory warranty?

[adamazing]

Are you out of factory warranty?

His tune was detected.