Gas/Crank Case Vapour Smell

[ryguy85]

I have a 2013 A4 (before the updated engines came out so the original spec is the 211Hp engine). Anyway, im tuned with GIAC Stage 1, have a carbonio intake and I have not yet completed the PCV recall ... I plan on doing that soon.

Anyway, I have started noticing over the last few months a gas/crank case vapour smell after the car has been turned off for 10 to 30 mins. I believe it is coming from the engine bay area since I can occasionally smell it outside the car and I also smell it inside the car for a few seconds after the car has been turned on (e.g. after turning off the car for 10 to 30 mins) and some of the outside air is drawn into the cabin by the HVAC system. I'm wondering if anyone else has experienced this ... could it be the PCV valve venting after the car is turned off?

[van462]

PCV doesn't vent to atmosphere. It's entire reason it exist is to prevent that. A fuel injector starting to stick could cause a fuel smell. It would dribble fuel into a hot combustion chamber after shutoff.

[ryguy85]

Well the pcv vents to the intake mf so I was thinking if the pcv was stuck open then you might smell some
Vapour after.

Regardless it doesn't seem that was the cause since I had the recall done and the issue still exists.

Anyway I could check for a stuck injector?

[van462]

You can pull your spark plugs and looks for a gas soaked plug. They will usually be burnt clean. You will usually notice a gas or rich running smell in the exhaust at idle. If you have carista or VCDS you could look at your fuel trims. Negative values indicate the ECU correcting for excessive fuel. Also worth noting the bank 1 sensor 1 O2 lambda. It should read 1 at idle and not really fluctuate. Lower than 1 indicates rich mixture (stuck injector). Strong gas smell with the oil fill cap removed is an indication as excess fuel is washing past the piston rings and into the oil.

[ryguy85]

I have vcds so ill take a look later to see my fuel trims and lambda.

[ryguy85]

Lambda is around 1.000 and Short term trim is around 0% (ocasionally drops to -0.8% but not lower) at idle. At this point I will try and localize the source to see if I can tell its coming from the intake (i.e. fuel in the cylinders) or else where in the engine bay. I took a quick look around and didnt notice anything out of the ordinary but I do not have tons of experience with this engine yet. I might try pulling the plugs this long weekend to see if anything weird is up.

[ryguy85]

So I did a bit more investigating and I think I have a leaking HPFP. I removed the engine cover shortly after turning off the engine and noticed a small fuel bubble on the top of the HPFP where it looks like the n276 valve threads into the main body of the pump (see red square on pic below). The part number on the top of the electrical connection on the valve is 06J 127 025G which comes up as the whole pump assembly itself in any search.

Questions:

1. Can I just try tightening this fitting or is it advisable to just change the whole HPFP since it doesn't look like that sensor on top is sold separately anyway?
2. Is it difficult to change the HPFP? I still have warranty but I am tuned so I am guessing the dealer might not be able to warranty this kind of fix.
2. I'm assuming this is the cause of the smell but is there anything else I should look into or be aware of?



pic from the top.

[ryguy85]

I confirmed today again that it's definitely coming from the top of the HPFP. Right after a 10 min drive the pump was dry but after i let the car sit and cool off for 15 mins I came back and there was definitely some fuel around the threads of the N275 valve.

I found it odd that the valve didn't get wet right after the drive and that I had to let it sit a while first. I'm inclined to think it's something to do with either what the position of the solenoid when the engine is off or its just the back pressure in there that eventually leaks out.

Either way I'm going to see what the dealer can do since I'm technically under warranty. Or il make this a fun diy.