From: andyg@microsoft.com (Andy Gillcrist)
Subject: GTI ignition trouble?
Date: 06 Nov 92 20:46:23 GMT
Organization: Microsoft Corporation
Distribution: usa



Hi once again,

Well, I just got my '89 GTI 16V back from its 60K service (actually,
62.7K).  Got a new timing belt, other belts & hoses, filters, fluids,
plugs, cap & rotor, and a heater core!  Compression is 205/195/210/205.
Nothing like a major tuneup to get the Fahrvergnugen quotient back up
where it oughta be.  I didn't replace the oxygen sensor due to momen-
tary budget constraints, but it'll be one of the next things I do.

So it's been running just fine for a week or so now, but as of yesterday
it's got a new problem:  the dreaded Intermittent Power Loss which most
of us liquid-cooled pilots have had from time to time.

In my case, the engine alternates randomly between running fine and
stumbling along at low power.  The period of this cycle ranges randomly
from less than a second to half a minute or so.

I suspect I've got one cylinder randomly not firing.  When it's missing,
there's a definite "d-d-d-d-d-d-d-d-d-d-d-d-d-" which is both heard in
the exhaust and felt through the car's body.  At cruise (3-4000 RPM),
the "d-"s happen about 10-20 per second (I can't count accurately that
fast), which works out to about 600-1200 per minute, which is roughly
1/4 of the RPM -- more evidence that one particular cylinder is unhappy.
It doesn't seem to be related to acceleration -- though the roughness
is much more noticeable under load.

Like I said, I just got new plugs, cap & rotor, and I've checked the
cap & rotor myself and they are indeed new parts and don't appear to
be defective.  I don't think this is a fuel delivery problem, or a dying
injector o-ring, 'cause in that case it'd run like crap all the time
instead of intermittently like it does -- that, to me, suggests an
electrical short or something of that nature.

Now, many of you are thinking "It's that new gas with [m]ethanol!  They
SAID it might cause problems like this."  I believe I can rule this out,
as the new stuff has only been on sale here since last Monday, and I
haven't bought gas at all since the Wednesday before.

So it really seems like an ignition problem to me, and I think I can
safely assume the coil is okay, as are the plugs (3 of them at least)
and the cap & rotor.  The fact that only one cylinder seems to be
involved makes me think I've got a dodgy plug wire.  Now, my question
for the net is:

How long can one expect an ignition harness to last?  60K seems to me
like a short time.  What's the earliest any of y'all have had to replace
the plug wiring on your car?  What are the symptoms when it starts to
die?

I see the 16V wiring harness from Neuspeed for over $100 (can't remember
exactly).  Before I blow that much on new parts that may or may not
solve my problem, I'd like to know what others think of my diagnosis.
Anyone else ever have this happen?

I'm also concerned that the unburned fuel is doing a number on my
catalytic converter.  Anyone know if this is a problem?

On a sort-of-related note, I finally fixed the flaky ground in my
stereo!  The doofus who installed it (not me, unfortunately) had the
whole system grounded to the ANTENNA SHIELD.  I'm pretty sure this
isn't standard practice.  :-)  The physical ground for the antenna is
the metal-to-metal contact where the antenna mounts to the roof, and
over time the metal nut tends to loosen and corrode a bit, hampering
the ground connection.  So I added a high-quality ground wire from the
radio cage to the ground stud behind the fuse box, and hey!  No more
static and ignition noise!

That's all for now.  Thanks to all who've responded to me in the past
on r.a.v, and thanks in advance for advice on my ignition problem.

-- 
Andy Gillcrist, SDE   | "Every five years or so, I look back   |     ///
Microsoft Corporation |  on my life and I have a good laugh."  | \\\///
andyg@microsoft.com   |     -- Indigo Girls, "Watershed"       |  \XX/ Amiga!