ignition/ poor running problems

[Huw Powell]

> 1987 4kcsq 105k mi

> Concerning the ignition system the Bently manual/
> Bible lists diagnostics and system descriptions for
> the 4cyl CIS-E and gt coupe
> CIS-III engine however there is nothing more than a
> page of statistics for the 5cyl JT (?) coded CIS-E
> quattro engine.

It's in there somewhere.  It's also fairly simple.  Start at the wiring
diagram for your car, the ignition system should be completely shown on
tracks 35 to 43.

> Am I to assume that the JT engine ignition is the same
> as the 4cyl system?

no

> Does the JT have a knock sensor and warning light? A
> hall sender and receiver?

No knock sensing.

There is a hall sender on the distributor (the small plug on the side),
which feeds a simple transistorized coil triggering device mounted above
your glove compartment.  There is a vacuum advance canister which I
believe mostly advances the timing as the throttle is cracked open, and
centrifugal advance for higher rpm's.  These are both easy to
troubleshoot with a timing light.

> I have been troubleshooting an intermittent poor
> running condition where the engine suddenly looses
> power and runs as if the timing
> is off, sputtering and possibly backfiring through the
> intake ( a loud popping noise of the air flow sensor
> plate in the intake is heard
> when throttle is applied at time of poor running).

> Knock sensor warning lamp #1 does not light up...
> my fuel relay #10 has no fuse slot!!

that's because the instructions you are following are not for your car.

Look up "ignition" in the index, that small page of specs is about all
there is to your ignition system.  it is fairly robust, and if you make
sure your cap, rotor and plugs are changed regularly and that your spark
plug wires are good, it should be trouble free.

> What might be the possible problems with the timing??
> The spontaneous behavior, surfacing and disappearance
> of the condition make
> me think that the problem is electrical, I.E.
> ignition.

The chances are this has nothing to do with your ignition (unless you
moved the dist and changed the timing, or some other fluke problem like
that).

Cars this old need some thorough preventative maintenance, and this is
more likley related to the overall functioning of your fuel system and
its associated electrical connections, and the various hoses involved in
the intake tract.

You will, in your Bentley, find a very nice two page diagram of every
component of your fuel system, followed by specs and diagnostics for
most for the devices.  Try looking under fuel injection controls and
continuous injection system in the "Engine" section.

You should check every piece of the system, undoing and cleaning *all*
electrical connectors, including the ground wires going to the intake
manifold and "spare" fuse on the side of your fusebox (it powers the
CIS-E computer).  Carefully check and as much as possible replace all
the hoses and molded rubber pieces on the engine.

Verify the reliable functionality of each component of the CIS-E
system.  Clean everything under the hood one part at a time.

I know this sounds like a lot of work, but just trying to hit some
defect with a "magic bullet" on a car like this is foolish, it is ready
for a more comprehensive understanding and also it's fifteen year
maintenance interval...

http://www.humanspeakers.com/audi/fifteen.htm

--
Huw Powell

http://www.humanspeakers.com/audi/

http://www.humanthoughts.org/