Crank Case Pressure?

I've measured a known good CJW at 51-52 in/h2o

45.5 inchs to 48 inches of water is about average on a known good crankcase breather on those 3.0T

1 1/2 to 2 psi would be similar if you are interested?

I don't know a good known spec, but, 45 to 50 in/h2o (124 mbar) sounds high. Are you able to remove the oil cap while the car is idling? what are you measuring?

Why,are you blowing a gasket or 2? No pun intended, I am just curious.

The CTUC engine will almost always throw a PCV code when the CCV valve fails, at least in our experience here. It will also only throw the one code only, with no other faults stored. That includes failures with oil caps you can barely remove and whistling seals.

What about the fuel trims? Does it have any effect on them like other PCV issues sometimes have?

Absolutely, but I always chase the crankcase vent valve before addressing any fueling issues. Here is a partial VCDS scan from our last whistling seal vehicle, we only replaced the CCV. Thursday,17,October,2019,15:08:49:13989 VCDS -- Windows Based VAG/VAS Emulator Running on Windows 10 x64 VCDS Version: 19​.​6​.​2​.​0 (x64) HEX-NET CB: 0.4508.4 Data version: …

Here's a 2015 S4 CGXC engine, same issue. Tuesday,23,July,2019,10:05:52:13989 VCDS -- Windows Based VAG/VAS Emulator Running on Windows 10 x64 VCDS Version: 19​.​6​.​1​.​0 (x64) HEX-NET CB: 0.4508.4 Data version: … DS308.0 Ross-Tech​.​com Chassis Type: FL-AU48 (8R0) Scan: …C … 5F 62 6C 72 A9 VIN: WAUBGAFL0FA130579 Mileage…

Brandon that is very interesting information! Currently i have measured -125 mbar + the oil fill cap is hard to remove. you can really hear it sucking vacuum when you pull it off... My STFT was -37% on both banks when i checked it yesterday. Could you confirm normal crankcase pressure on the CTUC ?? Others will claim normal crankcase pressure is -45 to -50 inh2o (125mbar) on these engines but…

I remember reading this case study! I grabbed all of the 3.0T we have in our showroom, the only one that wasn't consistent was an older 2012 A6 that was only reading -21 mbar, which supports the design differences around that era in your case study. All these samples are cold start after they've come down from high idle. I don't have engine codes for you, but they're probably a mix of CTUC and…

Thank you very much Brandon!! I am fearing i might be barking up the wrong tree on this one now... I am not so sure the crankcase pressure is my issue at this point. looking back on my fuel trim data from yesterday it was negative 37% (-37.5%) this engine is running very rich it appears. I will get this vehicle back into the service bay later today and check it out further then ill report back…

I would be leaning towards carbon buildup, either on the intake valves, restricting airflow and absorbing hydrocarbons, or the tips of the injectors causing them to dribble fuel. I'd lean towards carbon buildup depending on your mileage, that will skew fuel trims and airflow easily.

I started over with a fresh mind to reinspect / diagnose this vehicle as i felt i was making bad decisions and assumptions previously.... I reset the engine controller and took a short drive this thing is running horrible at this point even stalling at idle. 7 faults were stored after driving about 2 miles. (P0304, P0306, P0305, P0300, P2279, P0068, P130A) I decided to pull the spark plugs on…

Evidently you should be pulling the head. The cam does not look happy in this picture, and what is all of the debris from?

Yup, have to get your known goods in these! This is my cheat sheet I’ve been finally working on. I check most that come in and make a note and compare if I already have it on my list.