1984 4k - no start

[Ben Swann]

Vittorio,

Test the Hall sender with a VOM - you should see it go ~4V to < .5 V as it goes in and
out of window.  Ref. Bently for procedure.  You may have compound problem, so get spark
first.

If the DPR (differential pressure Regulator) is dirty/cruddy/rusty, it will create a
blockage and no start.  You can remove for cleaning. Get DPR O-ring kit from dealer.  A
light cleaning with very fine emory paper 800 grit or higher may help.  Clear any
blockage in port orfices with carb cleaner ( wear safety glasses).

O2 sensor! Will cause poor running as you describe and even stall the car, but usually
problem happens after engine is warm and goes into closed loop.

Rule out Fuel Pump relay by jumpering  - can use orange relay to simply have fuel pump
turn on constant with key. - use for diagnostics only.

Ben

[Date: Tue, 4 Aug 2009 10:42:59 -0400
From: "Bares, Vittorio" <Vittorio.Bares at nuance.com>
Subject: 1984 4k - no start
To: <quattro at audifans.com>
Message-ID:
	<624BC75DA4460545849070E141EBCD6B05926631 at BN-EXCH01.nuance.com>
Content-Type: text/plain;	charset="us-ascii"

So, has new wires, rotor, cap, plugs - was running fine - then about a week ago, while
driving it - it just stopped running.

I cleaned the contacts on the coil - started again, but wasn't running well. Almost as
if it was running on 4 cyl (it is a quattro 5cyl :-)). I was trying to diagnose by
pulling one sparkplug at a time while it was running, not much change when I did so -
consistently for all 5 plug wires.

Pulled the plug on the temp sensor in the rear of the head - no diff.

Pulled the plug on the sensor that is on the fuel distributor - no diff.

This morning - no start...

No spark.

I'm thinking hall sensor??
 
Vittorio -]