Narrowing down my start issue (84 4kq) [with suggested procedure]

[John Cody Forbes]

Correct me if I'm wrong, but isn't the DPR essentially a WUR in a small plastic case and mounted to the metering head?

-Cody (mobile)

On Aug 17, 2010, at 12:21 PM, "Ben Swann" <benswann at verizon.net> wrote:

> Cody,
> 
> This is probably why they did away with the WUR and went CIS-E. Indeed, the WUR is the
> main reason these fuel pressure tests were used.  CIS-e does not use it (WUR) and
> basically there is less need to do fuel pressure tests.  BTDT thinking I'd trouble shoot
> CIS-e the scame way as CIS, only to find out it became an irrelevant waste of time, and
> all the connections were competely different from CIS.
> 
> This reminds me of the story about the old man called out of forced retirement to fix a
> critical system so folks could have their Electiricity back.  He used to work on the
> system that he helped design and implement.    The officials stood around watching as he
> climbs down a manhole with a large screwdriver and comes up less than a minute later
> after turning a control switch with the screwdriver.  He hands them the $500 bill and
> they complain - Why so much? since all he did was to turn a screw to reset a breaker.
> He replied, " Yeah, but I know which screw on which control panel and in which manhole
> in which street."  "Come to think of it, don't you think I ought to charge you more -
> how much is the outage costing you per minute?"
> 
> Ben
> -----Original Message-----
> From: John Cody Forbes [mailto:cody at 5000tq.com] 
> Sent: Tuesday, August 17, 2010 10:14 AM
> To: audi at humanspeakers.com
> Cc: Ben Swann; quattro at audifans.com; Johnny B
> Subject: Re: Narrowing down my start issue (84 4kq) [with suggested procedure]
> 
> I have two five gallon buckets filled to the brim with bad warm up regs diagnosed with a
> simple fuel pressure test that takes 5 minutes. Changing parts on hunches and well meant
> educated guesses may work for those with parts cars or a fleet of similar cars, but in
> the professional world my customers don't want to hear "yeah I changed the temp sensor,
> see if that works". There is a test procedure for everything that can lead to fixing
> problems by only changing the things that are actually broken 90% of the time. I
> understand that not everybody has all of the equipment that a shop does, but in this
> case a fuel pressure gauge set is very inexpensive (cant they be had at Harbor Freight
> for like $40?) and would take a minute or two to install and KNOW what is going on with
> the fuel pump, injectors, DPR, and others. CIS is not like a carb or EFI system where
> the system pressure is important, but can be 10% off before it's noticeable to the
> driver. The system pressure on CIS is not even very important, but the control pressure
> that controls the movement of the metering plate is *critical*.
> 
> Now with that all said, is it possible this problem is ignition related? OP mentioned
> that the PO changed many things in the fuel system and had it looked at many times.
> Could it possibly be that he was barking up the wrong tree? IIRC the car in question has
> a basic ignition system (vacuum advance distributor, no ECU), right? It's sort of
> unlikely, but maybe the advance is sticking all the way retarded for a time?
> 
> Also, a smoke test would be pretty useful just to be certain of the vacuum system. I've
> made a "smoke machine" before out of a quart paint can with the lid soldered shut, some
> WD-40 or ATF as smoke fluid, two pipes soldered to the sides to let air in and smoke
> out, a propane torch to make the smoke, and an electric tire pump to do the air moving.
> Sounds silly, but I discovered and fixed a few small leaks on a car that way. 
> 
> -Cody (mobile)
> 
> On Aug 16, 2010, at 2:35 AM, Huw Powell <audi at humanspeakers.com> wrote:
> 
>> 
>>> Now that you have gotten to the point of things that Cody and Huw, 
>>> and others are pointing out, they may want to suggest clever ways to 
>>> do these tests.  Although I have done most of these in my ownership 
>>> of CIS cars, in most cases I never needed to go to the point of fuel 
>>> pressure tests  since I usually got things sorted by then.
>> 
>> I have never - NEVER - seen any need for fuel pressure tests.
>> 
>> Vacuum leaks and the resulting maladjusted static fuel mixtures, 
>> endlessly.  On almost every CIS engine I have encountered.
>> 
>> --
>> Huw Powell
>