2013 A4 running rich

[A4_Fire]

Hey,
I noticed lately that outside of the car I can smell a lot of fuel. My tailpipes have a lot of soot on them as well. This has lead me to believe it’s running rich.
It is tuned to stage 2, Downpipe and all that. But it’s been like that for well over a year, this is new.
I do my oil changes every 5-7,000km with liquimoly. Car had 50,000km when I bought it off a rich kid who probably didn’t treat it well. It’s at 85,000km now.
My initial thought is that the PCV piping has become clogged causing it to run rich. I changed the PCV when I bought the car but was lazy and didn’t do the pipes leading to and from.
Thoughts? Anybody have something similar?

[Bolshoi]

Did you replace with an OEM PCV? Check your diaphragm too, it wouldn't be the wildest thing for it to tear at 35,000km. I also had wet soot from my exhaust staining the floor before I fixed oil consumption.

[Theiceman]

why do you think a PCV would cause it to run rich ?

anyway how is the oil consumption , id check that, beyond that i will leave it to guys who know more about modded cars.

[A4_Fire]

I believe it’s the PCV because it helps recirculate I burned fuel is my understanding. It’s also a common issue with engine getting clogged or failing entirely from what I’ve read. Could be wrong tho

[Theiceman]

I believe it’s the PCV because it helps recirculate I burned fuel is my understanding. It’s also a common issue with engine getting clogged or failing entirely from what I’ve read. Could be wrong tho

pcv takes gasses and blowby out of the crankcase and recirculates them into the intake to be burned and is part of emissions . I would say it is not causing a rich running issue. There are people who believe this causes excessive buildup on the intake valves and it certainly may contribute, but i still don't think it would cause any of the issues youa re seeing.

[JLAllroad]

Scan for codes, report back.

That said, rich would/could be leaking hpfp or injectors, the latter is often accompanied by single cylinder misfires.


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[A4_Fire]

I don’t have any misfires, I have heard about the common HPFP failures and that has been known to make it run rich or lean. Definitely something I’m considering

[A4_Fire]

There’s no engine codes, but I checked the fuel trim numbers. Short is 0% and long is +10.8%. I’m told a combination of both numbers shouldn’t be exceed 10% or it’s rich and won’t throw a code until 20%
PCV diaphragm seems good, no vaccine leaks or exhaust leaks detected
My 2 main suspicions are now the PCV hose getting clogged, or HPFP failure

[JLAllroad]

There’s no engine codes, but I checked the fuel trim numbers. Short is 0% and long is +10.8%. I’m told a combination of both numbers shouldn’t be exceed 10% or it’s rich and won’t throw a code until 20%
PCV diaphragm seems good, no vaccine leaks or exhaust leaks detected
My 2 main suspicions are now the PCV hose getting clogged, or HPFP failure

Monitor hpfp hot idle pressure, turn engine off, it should continue to rise to 2-3x idle pressure, if it doesn’t it’s more than likely leaking, although again it could indicate an injector leak.


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[featherman]

Oil level rising, or does the oil smell like gasoline? Any hard starting issues? I had similar symptoms, and it was a leaky HPFP. Fuel diluting oil, PCV system picking up the fuel vapor and burning it in the cylinders.

[A4_Fire]

Update:
I went and smelled the oil throughly. It does smell like it has fuel in it. To be more sure, I compared it to my TT which has 3k on the oil and not noticeable smell. Fresh out out of the jug had no noticeable smell. But the A4 oil which has max 500km on it, definitely has a smell of something else. I’m 99% sure there’s fuel in the oil now. Making me think it’s the HPFP a lot more now

[Waffles_s4]

Update:
I went and smelled the oil throughly. It does smell like it has fuel in it. To be more sure, I compared it to my TT which has 3k on the oil and not noticeable smell. Fresh out out of the jug had no noticeable smell. But the A4 oil which has max 500km on it, definitely has a smell of something else. I’m 99% sure there’s fuel in the oil now. Making me think it’s the HPFP a lot more now

ITs either the injectors leaking or HPFP. Do you have hard starts specially in hot weather?

Pull the plugs, and open the door for the fuel pump tp prime. if u smell or see fresh oil in the cylinders, you know its the spark plug(s) leaking.

I just replaced my HPFP because of fuel in the oil.

[A4_Fire]

- FINAL UPDATE -

I replaced the HPFP as I suspected it was the culprit, also cam follower since I was already in there.
Since then fuel efficiency immediately improved dramatically. Used to spend 100km of fuel range travelling about 30km and now it’s closer to 35-40km of range (bc tune).

The smell of rich fuel out of the exhaust has been diminishing over time as PCV burns the fuel Vapor’s left in the oil (may change oil again just to be a good owner).

Thanks for all input and advice !

[silver_tt]

That is great news. I would change your oil now that the HPFP is swapped out -- your fuel dilution is probably off the charts so I would change it ASAP if you didn't already.