[V8] A8 emissions problems

[Jason Wilkerson]

Thanks for the reply guys.  I did a slight overpressure test last night.  I put probably 0.25 psi on the tank and lines last night.  Went around with soap spray on all fittings tank tops, etc.  Found one small leak around sender on tank.  Re sealed it, reset codes.  We'll see what happens.  I think I still hear the noise though, so I'm not getting my hopes up yet.  If this doesn't do it I'll replace the evap purge valve - at least I can re-sell it when I'm done if it doesn't work.  Thanks again.


From: "dsaad at icehouse.net" <dsaad at icehouse.net>
To: v8 at audifans.com
Sent: Tuesday, October 25, 2011 1:47 PM
Subject: Re: [V8] A8 emissions problems

Jason, most cars I have looked at have some sort of pressure sensor on the
gas tank.  If it will not hold vacuum maybe that is the source of the
problem?  Maybe in the "crash", something came loose on the tank?

This actually might tie into what I was going to post today anyway - that
all the fuel lines under the hood are likely ready to fail if they came
with the car (talking about V8s here).  I had to remove mine for the
steering rack R&R and both the supply and return lines broke.  They were
baked to a crackly crunch and brittle as glass.  Same for the two rail to
rail hoses on the manifold.  The supply hose broke as I was re-installing
it.  The return hose broke while I was driving a few days later. 
Fortunately the motor was cold and I was close to work or it could have
been ugly.

I had the supply hose rebuilt a few years ago  and it was the worst of
them all. The hose they used did not hold up to the heat at all.  This
time I went with a hi-temp hose so we will see how that goes.  The shop
did not have anything like the OEM hose - which has some sort of hard
plastic inner.  I hope that is not a problem - but really don't have a
choice at the moment.  Cost to rebuild all four hoses was under $25.  I
have heard that the hard plastic inner is needed for proper/precise
operation of the fuel injectors so I will let you know how it runs after I
get it back together.

The hose I used is rated for oil temps of 300 degrees,  made by Parker,
and is blue.  He had some stainless braided stuff but it was lower temp
rating.



Dave



> Guys,
>   I know this is the v8 forum but I have come to realize you all are a
> wealth of info on audis in general.  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.
> _______________________________________________
> Audifans V8 mailing list
> Send posts to: mailto:V8 at audifans.com
> Manage your list connection: http://www.audifans.com/mailman/listinfo/v8
>
> You can help keep the audifans site running by shopping at
> http://audifans.com/shop/
>
>


_______________________________________________
Audifans V8 mailing list
Send posts to: mailto:V8 at audifans.com
Manage your list connection: http://www.audifans.com/mailman/listinfo/v8

You can help keep the audifans site running by shopping at http://audifans.com/shop/