'86 5000TQ no start...

[John Forbes]

Thanks for all the suggestions so far. Tomorrow I think I'll try again on
getting diagnostic mode. I started today back in the Bentley before I
recieved any of the replies (straight from work to working on the car,
ckecked emails after I got home at 2:45am :-( ) back at trying to get into
diagnostic mode again. First thing I noticed was a big laugh at the time - I
must not have been paying enough attention, the first time I went through
trying to get into diagnostic mode I was in the wrong section of the book! I
had been reading from the 84-85 Turbo section rather then the 86-88 Turbo
section and the process is very different. (For those not enlightened) The
earlier version after cranking you must hold the WOT switch closed while the
throttle is at idle position for ~3 seconds then the code reads out on the
tach; the later cars such as mine after cranking you must insert a fuse into
the spot on the fuel pump relay for ~4 seconds then the code reads out.
Still same though, no go after many tries, the fault light doesnt light up
or anything. Incidently this helped me narrow the problem down a bit. When I
went to insert a fuse into the relay there was already one there, which
caused about two hours trying to figure out why without the fuse I had no
fuel pump, and why with it the fuel pump ran after a short delay when
ignition was turned on, but stoped as soon as the motor cranked over. Then
it hit me. Has to be something involving loss of power during crank. So I
had my friend helping me install a test light on the blue&black wire on the
resistor pack of the coil - lo and behold, power was cut when cranking.
First thought was ignition switch, which of course isn't covered (at least
not that I could find) in the bentley, so I pulled the wires off the back of
the switch and manually figured out what each is with a test light and a few
jumper wires. Upon cranking now using jumper wires instead of an ignition
switch I still had same problem, no fuel pump and no coil power when
cranking, but then after a few times of testing this way I noticed that it
would give power back to the coil and start the fuel pump for maybe half a
second immediately after I stop cranking, but only sometimes. Obviously
something is being very very strange here. After hooking the ignition switch
back up it did the same thing. I'm thinking theres got to be a short
somewhere in the main harness involving cranking power, but I dunno. Being
my first Audi, and the first one with electrical problems thats ever been to
my shop (work at a Porsche shop) its got me stumped as far as thinking of
something from knowladge, but I know its something that eventually with help
of the bentley and you guys I'll be able to figure out.

The worst part thats really annoying is that I have a MegaSquirt EFI
controller ready to go, but I wanted to drive the car for a bit with the
stock systems just to make sure the motor and driveline are healthy. I even
have a Q-list code chip ready to go in my spare ECU, was planning on swaping
the ECUs after I knew the CIS and ignition was right (maybe a few days of
driving) so I could have some fun until I got my EFI parts finished (fuel
rail, injectors, TPS). Which leads to another more simple question. I
remember reading somewhere that the CIS injector inserts in the manifold
come out easily and I can put EFI inserts in very easily. Any thruth to
this, and if so where can I get a set?

Thanks again,
-Cody

----- Original Message -----
From: "james accordino" <ssgacc at yahoo.com>
To: "John Forbes" <john at craincorporated.com>; <quattro at audifans.com>
Sent: Wednesday, January 15, 2003 4:33 PM
Subject: Re: '86 5000TQ no start...


> This might seem stupid, but do you get 12 volts input
> at the coil?  Solid spark from the main coil wire
> while cranking?
>
> Jim Accordino
>
> --- John Forbes <john at craincorporated.com> wrote:
> > This is a multi-part message in MIME format.
> > --
> > [ Picked text/plain from multipart/alternative ]
> > Hi all. I've been chasing ingition problems with my
> > 5ktq for over a month now and its getting pretty
> > frustrating. It seems to have been an intermitent
> > problem, sometimes it will start and run fine, then
> > a minute later it will be back to no spark. Until
> > recently; I guess now it has made up its mind, past
> > few days I've been solid with no spark. When going
> > through the ignition testing in the Bentley I first
> > tried the on board diagnostic to no avail, couldn't
> > get the car to switch into diagnostic mode. I then
> > went through testing every component thats covered
> > in the ignition secion of the manual. When testing
> > the hall sending unit everything came back ok, even
> > the wiring tested good. The bentley suggested
> > replacing the hall control unit, is this the same as
> > the main ECU? I have already replaced the main ECU
> > with one from Specialised German Recycling so I just
> > ignored it and went to the next steps. I got to the
> > coil and it suggested replacing the coil, so I did
> > with a known good one, but still no spark. I've
> > already replaced virtually everything, the hall
> > sensor, the ecu, the coil, cap & rotor, both
> > flywheel sensors and checked all wiring to be good,
> > but still no spark. Any suggestions about where to
> > go next?
> > --
> >
>
>
> __________________________________________________
> Do you Yahoo!?
> Yahoo! Mail Plus - Powerful. Affordable. Sign up now.
> http://mailplus.yahoo.com
>