[A8] 99 a8 emissions problem

[Cody Forbes]

A "large" evap leak is a pinhole larger that .010". If its that small you wont be likely to find it without a smoke machine.

-Cody (mobile)

On Oct 25, 2011, at 8:55 AM, Jason Wilkerson <wilke_jb at yahoo.com> wrote:

> Guys,
>  
> I have an issue with my 1999 A8. The CEL came on the other day. Two codes - 
>  
>     16839/P0455 - Evap system, large leak
>     16825/P0441 - Evap system, incorrect flow, intermittant.
>  
> I have checked the following:
>  
>     Purge valve, pulled vac on the engine side, no leaks. Tested electrical operation, works fine. Tested on car and it modulates     like it should - OK
>  
>     Fuel expansion tank for leaks, visually and with pressure - OK
>     
>     Fuel cap and neck - OK.
>  
>     Fuel tank lid with seals for sender and fuel pump - OK.
>     
>     Carbon canister under spare tire - OK.
>  
>     Evap test pump - Not sure?
>  
> Here is the run down:
>  
>     Before the CEL illuminated, I was hearing a 'whining' sound coming from the pass rear wheel. Turns out it is some sort of check valve in the expansion tank above that wheel. I don't think this is the problem, but just a symptom.
>  
>     Not sure if it is relevant, but before I started to hear the 'whining' and before the CEL, I backed into a building. It was not hard and really didn't even put a mark on the car, but - it would seem that it was about the same time that this happened and the same time that it currently takes to reset the CEL.
>  
>     I pressure checked the whole fuel system last night and found nothing leaking.
>  
>     I'm leaning toward the evap test pump - I may have to buy one anyway because I broke one of the fittings off trying to remove it to look for anything obvious.
>  
> SO - any suggestions? I am at a loss. Thanks in advance.
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