[urq] Sudden lean running 10v

[Keith Lloyd]

Mike
I had something similar back in 2006. Car would pull like a train under 
initial accelleration but when I then changed up it went totally flat (meter 
showed lean mix at that point). If I lifted off and re-applied the pedal it 
would pull again (with a rich mixture as one would expect). Never got to the 
bottom of it. It got better with time. One lister asked if I had recently 
run a fuel additive or injector cleaner through it which I had. This may 
have dislodged crap which clogged things intermittently. Perhaps you have 
done the same? Even now occasionally I notice that the mixture is a little 
leaner than normal  for a trip or two (yes, I run a permanent AFR meter). I 
still have suspicions around the WUR or perhaps the needle sticking in the 
metering head but as it is now very occasionally a problem I can't bring 
myself to dive in to find the cause. It might do more harm than good. With 
lean mixture it's probably not best to try an italian tune-up to fix it but 
if it was a lesser car than a quattro I might try it or with someone elses 
:-)
Yours does sound like a fuel delivery issue - unable to supply sufficient. 
And you have the "advantage" of a permanent rather than intermittent issue. 
In the past people have said the three things to check are fuel presure, 
fuel pressure and fuel pressure. I guess if you run the tests you ought to 
be able to narrow it down.
I'm afraid I can't help more but I will be interested to know what it was 
whe you do fix it.
All the best

Keith

'87 WR (in warm sunny Worcestershire)

----- Original Message ----- 
From: "Brandon Rogers" <brogers at terrix.com>
To: "'Mike Del Tergo'" <mdeltergo at hotmail.com>; <urq at audifans.com>
Sent: Monday, June 27, 2011 5:04 PM
Subject: Re: [urq] Sudden lean running 10v


> No good answers here - just a few thoughts...
>
> Did you do the t-belt - off a tooth?
>
> Do you have a local "neighboring" car that you can compare all your
> electrical connections?
>
> Have you re-adjusted or checked freq valve duty cycle on the DMM?
>
> Brandon
>
>
>
>
> -----Original Message-----
> From: urq-bounces at audifans.com [mailto:urq-bounces at audifans.com] On Behalf
> Of Mike Del Tergo
> Sent: Tuesday, June 21, 2011 6:38 PM
> To: urq at audifans.com
> Subject: [urq] Sudden lean running 10v
>
>
>
> Ihad the engine pulled last fall to clean up the engine department and 
> drop
> in my rebuilt rack. Finally got a chance to play around with it after the
> engine went back in and had a lot of electrical connections to correct 
> that
> the wrench was not sure of.  I have had an O2 in it for some time with an
> AFM.  Car starts fine cold and hot, and shows correct very rich on cold
> start.  It would always go to full rich under firm acceleration.  Now 
> after
> the engine pull, I barely get mid range AFR and dreaded pinging if I goose
> it.  Car will slowly rev past 4K so IAT switch seems fine.  Hwy cruise is
> fine.  Both throttle switches show on/off functionality so I am at a bit 
> of
> a loss.
> Ideas?
> _______________________________________________
> Audifans urq mailing list
> Manage your list connection: http://www.audifans.com/mailman/listinfo/urq
> http://www.audifans.com/kb/List_information
>
> Pictures/Polls/Database at: http://autos.groups.yahoo.com/group/urquattro/
>
>
> _______________________________________________
> Audifans urq mailing list
> Manage your list connection: http://www.audifans.com/mailman/listinfo/urq
> http://www.audifans.com/kb/List_information
>
> Pictures/Polls/Database at: http://autos.groups.yahoo.com/group/urquattro/
>
>