[urq] Freq valve failure?

[dgraber460 at aol.com]

Are you sure it is not a Oxy-fuel vapor lock issue? My WX had a nasty time with the Oxygenated fuels. It vapor locked more in the winter when the switch was made for smog consideration. The FV can't compensate for air bubbles in the fuel. Just a thought.
I probably have a FV I could send. I'll check tonight.


Dennis 
Denver



-----Original Message-----
From: Eric J. Fluhr <ejfluhr at austin.rr.com>
To: urq at audifans.com
Sent: Tue, Apr 26, 2011 11:44 pm
Subject: [urq] Freq valve failure?


Gang, 
 
Has anyone experienced a faulty fuel frequency valve that fails when it gets too hot? 
 
I have been facing a problem with my '82 WX whereby it runs great at first drive (good stoichiometric 
fuel control). If I stop somewhere and then restart it after a short rest, it runs exceptionally lean (I have 
a wideband O2) at anything off-idle. At idle, it runs a tad rich. Recently as it is getting very hot here, it has 
started switching to this behavior live when the car is already hot and heat-soaking sitting in traffic. 
 
I have been testing various subsystems over time, without luck. Now I am focusing on the FV. 
I have measured the FV duty cycle at the test connector, and the computer is behaving correctly: 
~5% duty cycle at idle, ~92% duty cycle off-idle as it tries to compensate for the rich & lean mixtures. 
Just this evening I decided to disconnect the electrical connector for the FV while the car was having 
this problem, and it behaved approx. the same on the ensuing drive. 
 
So, the smoking gun points at the FV, but have never heard of one failing. I'm not sure if these can even 
be sourced, as it seems to be unique to the WX at least based on part number. I'm wondering if I can 
use a more readily available model (e.g. MC) and just change the hoses crimped to the ends. I need 
an inexpensive solution because I have a 20vt waiting in the wings and just need the car to survive long 
enough to prep that. 
 
Any help/info is appreciated. 
 
Thanks, 
Eric 
'82 Urq, limping along  
_______________________________________________ 
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/