[urq] Ideas for rough running continued - Solved!

[Stephen Redford]

----------Hi Ben ,  I gather from your post that you are talking about a Urq '83-'85 US model ?    I was not aware that  I had a hall sender on my '85 Urq.  I thought I just had a distributor...  Javad said that was one of the things I was going to have to get from a wrecking yard and install before I could buy/use his electronic fuel system , because his system requires a Hall Sender ... ??   Am I misunderstanding something ... Stephen - feeling ignorant    :)))


  ----- Original Message ----- 
  From: Ben Swann<mailto:benswann at comcast.net> 
  To: ekellock at gmail.com<mailto:ekellock at gmail.com> 
  Cc: urq at audifans.com<mailto:urq at audifans.com> 
  Sent: Thursday, April 07, 2005 6:06 AM
  Subject: Re: [urq] Ideas for rough running continued - Solved!


  I don't know if this will help, but as I am sorting out mine presently, have
  gleaned some information on the way things work with the WX engine.

  One thing that you may not be aware of is that the idle control is done by
  advancing the timing which is different than on the later MC Turbo and the
  NA engines.  I don't recall there being an idle compensation valve/switch
  that lets more air in as the RPMs drop.

  In any case, these events are triggered by the primary signal output by the
  hall sender - this signal/lead/wire goes directly to the F/TCU (Fuel Timing
  Control Unit) and processes  this signal  in conjunction with the Speed and
  Reference signals (flywheel sensors), Manifold Pressure, Coolant temp and
  air intake senders to advance and retard the timing..  The processed signal
  is output  to the fuel pump relay and Ignition Control Unit and presumably
  the tach.

  By use of the Idle Switch located on the throttle body, the Idle Stabilizer
  Function of the F/TCU is switched on if the engine speed is below 820 RPM
  and the ignition timing advanced/retarded to regulate the idle speed.

  Again, I haven't seen any reference to an idle air stabilizer valve like in
  many other cars, although there appears to be an auxiliary air valve -
  probably used during warmup and simply controlled by the thermo time switch,
  which is just an educated guess.

  BTW adjusting the distributor will do nothing for the timing.  It is either
  "in window" or not.  Of course it is good to have the distributor set so
  that the hall windows are dead center, which would  be best should there be
  any slop in the mechnics of the distributor.  By using the two flywheel
  sensors in concert with the hall signal, the F/TCU knows exactly what the
  crank position is and the signals are synchronized.

  Diagrams help to explain this and the best source are the two documents
  online "Audi Turbo Quattro Introductory.Service Training Information: and
  corresponding "Maintenance and Adjustments". These two documents will
  explain things far better than one ever could in an email.  Perhaps someone
  has these links - I lost all my links in a hard drive crash and am presently
  rebuilding them.

  HTH

  Ben

  [Date: Wed, 6 Apr 2005 19:41:22 -0600
  From: "Ed Kellock" <ekellock at gmail.com<mailto:ekellock at gmail.com>>
  Subject: Re: [urq] Ideas for rough running continued - Solved!
  To: "UrqList" <urq at audifans.com<mailto:urq at audifans.com>>
  Message-ID: <000a01c53b12$e8fa6020$9f0a2146 at clspco.adelphia.net<mailto:000a01c53b12$e8fa6020$9f0a2146 at clspco.adelphia.net>>
  Content-Type: text/plain; charset="iso-8859-1"

  I may have had an "AHA!" moment.

  I went out the adjust the distributor subsequent to my weekend post
  and Ingo's response to see if anything changed with my ignition
  cutout.  It didn't.  The car started easily but sure enough the
  ignition cutout is still there.

  As I sat there opening and closing the throttle, I noticed that the
  cutout seemed to occur as soon as I lifted my foot.  Once in a while
  it would happen a moment later as the rpms fell.  It did it reliably
  enough that I believe I can connect the behavior with the symptom.
  Not high rpm's involved, most of the time it was nothing over 2500.

  When the ignition cuts out, the tach needle drops every time but the
  fuel gauge seems to be unaffected.  And the relay in the fuse panel
  that clicks doesn't do it every time, only when the duration of the
  cutout is longer.

  What's the gizmo that holds the idle up a bit until the car warms, the
  idle control?  I think the temp sensor for mine is somewhat defective
  because the rad fan had already kicked on once before the idle control
  let the idle drop down to a more normal warm idle.  As soon as this
  occurred the cutout started happening by itself repeatedly but not
  necessarilly enough to kill the engine.  When I opened/closed the
  throttle to keep it running I found that I could reproduce the cutout
  much more directly always on decel or lift throttle.

  Anyway, all of this reminded me of Ingo's sticking fuel plate spring.
  Now, maybe I'm pairing apples and oranges a bit here, but the
  similarity is interesting at very least.

  Is there any relation between the lack of air flow and resulting fuel
  cutout as in Ingo's case and the ignition trigger?

  Ed]

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