Crank Case Pressure?

Bill Owner/Technician Michigan Posted   Latest   Edited  
Resolved
Driveability
2013 Audi Q5 Premium Plus 3.0L (CTUC) 8-spd (0BK) — WA1DGAFP4DA069260
P2279 — Intake Air System Leak Bank 1
P0068 — MAP/MAF - Throttle Position Correlation
P0300 — Random/Multiple Cylinder Misfire Detected

Hello - I am Looking for know good crank case pressure on this Audi 3.0T Engine Code CTUC. I believe i have a failed oil separator/ crankcase vent but i do not have a know good reading on this specific engine code. If you do thanks for sharing !!

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Hans Diagnostician
Utah
Hans Default
 

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

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Anthony Technical Support Specialist
California
Anthony Default
 

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

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David Owner/Technician
Alberta
David Default
 

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

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Nicholas Diagnostician
New York
Nicholas Default
   

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?

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Stuart Mobile Technician
Illinois
Stuart Default
 

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

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Brandon Technician
Minnesota
Brandon Default
 

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.

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Stuart Mobile Technician
Illinois
Stuart Default
 

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

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Brandon Technician
Minnesota
Brandon Default
   

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: …

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Brandon Technician
Minnesota
Brandon Default
   

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…

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Bill Owner/Technician
Michigan
Bill Default
 

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…

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Brandon Technician
Minnesota
Brandon Default
   

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…

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Bill Owner/Technician
Michigan
Bill Default
 

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…

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Brandon Technician
Minnesota
Brandon Default
 

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.

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Bill Owner/Technician
Michigan
Bill Default
 

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…

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David Owner/Technician
Alberta
David Default
 

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

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Hans Diagnostician
Utah
Hans Default
 

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.

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Bill Owner/Technician
Michigan
Bill Resolution
   

Found a broken exhaust valve spring on cylinder 6. See the related pics and further details in my last reply

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