Hey guys,

I'm disappointed to introduce myself to the forum in this manner, but unfortunately I was forced to join as to discuss the problem I have with my car

I always enjoyed reading the wealth of info on this forum, as well as enjoying the vast number of beautiful photos of other members cars on here!

Long story short, my 2006 audi a4 2.0T 145km shows the following symptoms:
- Doesn't start after filling up unless I floor the gas pedal, and will run VERY rough at first - the problem goes away after driving off and car starts flawlessly until I fill up the next time
- When I first run the car in the morning when it's cold, upon breaking I hear a knocking noise coming from the rear on the drivers side
- CEL light is on
- VAGCOM shows codes for an EVAP large leak and intake manifold getting stuck
- My wonderful mechanic says the car creates a vacuum when it's not supposed to?
- My wonderful mechanic replaced some celonoid valve which broke again within a day of driving
- Since the problem started, the engine sounds odd... very hard to explain but it does excessive muffled "clicking" noise that it didn't do before

Anyways, after extensive research on the forums, I believe I found the exact problem - N80 purge valve

So, I will replace the N80 purge valve, as well as the check valve that comes before it and the broken celenoid valve (perhaps it's even the same part? forgive my limited auto tech knowledge)

But my actual reason of this thread is:
What the hell is that knocking sound that I hear if I break when the car is cold in the morning??? What do I replace to get rid of it? I'm pretty confident it is related to the whole EVAP problem as it all started happening simultaneously.

 

Evap leaks are usually caused by not tightening the fuel cap, and EVAP purge valves. It could also be the fuel tank, LDP, EVAP canister, or any hose or line between these.
Do you top off your fuel tank?
When the pump stops you should stop. If you don't the evap canister can fill with fuel. This can damage the N80. If the N80 sticks open it causes an evap leak(usaully not a large one though.) The knocking you hear is the Leak Detection Pump (LDP). It runs to check for EVAP leaks. If a leak is present you are more likely to notice it because it runs longer.
N80s
What is the fault number for the intake?
Anyways you probably need an intake flap motor and/or the updated ECM software.

 

Hey,

Thanks for the reply.

Yes, it turns out my girlfriend tops off the fuel tank everytime she fills up!!!! Well used to.

My mechanic is getting back to me with quotes for replacing the N80 valve, check valve before it, and intake flap motor.

When I first got this problem, I replaced JUST the n80 valve and it broke 2 days later... ? Hopefully by replacing what I named above it won't break again.