1984 4k - no start quattro Digest, Vol 71, Issue 30

[Scott]

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Message: 4
Date: Sat, 19 Sep 2009 19:14:01 -0400
From: Huw Powell <audi at humanspeakers.com>
Subject: Re: 1984 4k - no start
To: "Bares, Vittorio" <Vittorio.Bares at nuance.com>
Cc: Ben Swann <benswann at verizon.net>, quattro at audifans.com, Tony
    Hoffman <auditony at gmail.com>
Message-ID: <4AB565B9.3060007 at humanspeakers.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed


> Well the car starts and runs. After its warm though, it no longer
> starts. Today it would need to sit for just a few minutes before it
> started again.

This is common issue which Audi altered quite a few things over time to 
"prevent".  It could be a combination of a faulty fuel check valve 
(letting pressure drop) and heat soak at the head, vaporizing fuel in 
the injector lines.  Can result in long cranking, or even no-start until 
things cool a little.

Heat buildup has also, IIRC, been implicated in intermittent Hall 
senders on the dizzy.

> While running, I can tell it isn't running well on the low end.

Might be a completely different issue.

> For the no-start the O2 sensor may make sense as it seems to have
> trouble after warm up.

O2 sensor not used while starting.  Easy to test when warm running, 
though - voltage should cycle up and down between about .3 and .7 volts 
DC every few seconds.

> For the not running well - I'll take a shot at the DPR.
> 
> Now to your comments - I thought the DPR was the assembly directly
> over the fuel meter arm sitting on top of the airbox. Which is the
> fuel distributor?

The DPR is the little grey box on the front of the fuel distributor with 
an electrical connection.  Two bolts hold it on; there are two small 
o-rings to make sure you don't lose (or have new on hand).

Have you made sure *all* the electrical connections (especially CIS ones 
of course) under the hood are clean?


-- 
Huw Powell

http://www.humanspeakers.com/audi

http://www.humanthoughts.org/


------------------------------

Message: 5
Date: Sat, 19 Sep 2009 19:28:54 -0400
From: "Bares, Vittorio" <>
Subject: RE: 1984 4k - no start
To: <audi at humanspeakers.com>
Cc: Ben Swann <benswann at verizon.net>, quattro at audifans.com, Tony
    Hoffman <>


Message: 6
Date: Sun, 20 Sep 2009 12:58:50 -0400
From: "Ben Swann" <benswann at verizon.net>
Subject: RE: 1984 4k - no start
To: "'Bares, Vittorio'" <Vittorio.Bares at nuance.com>
Cc: quattro at audifans.com
Message-ID: <006201ca3a13$a0c00990$0201a8c0 at swansong>
Content-Type: text/plain;   charset="us-ascii"

Yes - remove and take apart as best as you can.  Use very fine emory paper to 
get the
surface clean.  They are difficult to take apart, and so just as well to spray 
carb
cleaner through the orfices.  Lastly - replace the O-Rings, dealer has a kit.  I 
may
have an unused kit.
 
Ben

  _____  

From: Bares, Vittorio [mailto:Vittorio.Bares at nuance.com] 
Sent: Saturday, September 19, 2009 5:28 PM
To: Ben Swann
Cc: quattro at audifans.com
Subject: RE: 1984 4k - no start



Hi - back to the 4k now that the S6 is running well.

 

The DPR - are you suggesting opening it up and cleaning it? Just want to be sure 
before
I do since ETKA doesn't have an exploded view of the internals.

 

Thanks!

 

Vittorio -

  _____  

From: Ben Swann [mailto:benswann at verizon.net] 
Sent: Tuesday, August 04, 2009 9:38 PM
To: Bares, Vittorio
Cc: quattro at audifans.com
Subject: 1984 4k - no start

 

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:  
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