[V8] Audi crankies

[Acadianlion]

I'm driving the V8 sixty miles four times a week right now. That's 
pretty much a minimum, and the sixty miles are a guestimate because my 
speedometer is cranky and doesn't work the entire trip.  The ride is 
over two-lane, rural roads with extremely light traffic...sometimes I 
see only one or two other cars the entire trip once past the stop light 
in Brooks Village.  Anyway, yesterday it was rainy and coolish but not 
cold.  My stumbling problem appeared to be gone until I got to Route 7.  
The left turn onto Route 7 at the blinker begins a sharp hill that is 
perhaps a third of a mile in length so the car is working to 
accelerate.  Immediately upon turning onto Route 7 and climbing, the 
lumpy, cylinder miss reappeared.  CLEARLY the engine was not firing 
properly on eight cylinders at that point.  By the time I got to the top 
of the hill and load was removed from the engine, it smoothed out, but 
for the next five or six miles, I could feel the engine's uneven running 
through the steering wheel.  This was the most pronounced it has been in 
some time.  Ten miles later, I felt something "give" and the engine was 
smooth again, all the way to the end of the drive.

When I came out of the session, it had been raining quite hard, but no 
trace of the roughness was present for most of the trip home which was a 
complete retrace of the trip out. Hilly, open countryside.  A bit of 
stumble but not at all as bad as during the first part of the trip.  The 
car had been in the closed garage over night and spends ALL its nights 
there.  But I am again wondering about distributor caps or wires.  It 
seems strange a plug might be fouled, partially or mostly clear and then 
foul again. Once again I am thinking of buying some plugs and changing 
them out myself to see what that does.  The car goes to the wrench next 
month for its inspection and an oil change.

Oh, and the speedometer.  It continues to be cranky.  Yesterday for the 
first few miles it worked fine, then quit.  On the return trip, it 
worked fine after the first few miles.  This might be temperature 
related, but if that is the case, why does it sometimes work when 
started cold, then once fully warmed, quit?  I no longer think it is a 
ground issue in the cluster.  Rather I am leaning hard toward the idea 
that the sender is faulty as Dave Saad said, and will check that.

Oh, and one more cranky issue.  We went to Sam's Club last week and we 
usually take the 100 Quattro Avant for that trip.  We were mostly there, 
driving in, in-town Bangor traffic when the car began to steadily lose 
power.  And lost power it did to the extent that it would only crawl and 
was mostly unresponsive to the accelerator. This was potentially serious 
as we were fifty miles from  home.  I was able to get the car to crawl 
into Walmart where I dropped my wife.  I knew the fuel was low...perhaps 
a quarter of a tank at that point, so I restarted the engine and drove 
back onto the road. Surprising that when I restarted the engine after 
only a moment or two of sitting, the car came right to live and behaved 
as though nothing was wrong. I drove a mile to a station and filled the 
tank. Later, I picked up my wife and we drove across the city to Sam's 
and did our shopping.  The return trip was uneventful, no loss of power.

My analysis:  In late December there was a new fuel pump installed, but 
the fuel filters were not changed.  I may have an occasional 
sludge/clump of something that is working its way around a fuel filter 
or line causing a momentary blockage or restricting fuel flow.

ALSO:  for years and tens of thousands of miles this car has 
periodically thrown a "check engine" light.  It comes and goes.  The 
wrench has pulled the codes on this antique car dozens of times. No 
obvious issue. His diagnosis is perhaps a distributor or something 
electronic, but since the car runs fine, and ALWAYS runs fine and the 
same way with no outward issues that seems related to the check engine 
light, I have not thrown diagnostic dollars at this phantom. Yet it 
occurs to me that this might be an incomplete firing issue that occurs 
from time to time and gradually the catalytic converters have become 
become fouled.  Saying that though brings the question of how is it that 
once fouled how do they clear in a matter of seconds when the engine is 
stopped.

I suspect this to be a fuel pressure issue.  It has happened three times 
prior to last week, always after running for thirty miinutes or so, and 
always clearing when the engine was stopped and restarted.

Do you out there in the Audi Brain Trust agree that this likely is a 
fuel pressure/filter issue?  (Oh, yeah....I really need to get the fuel 
sender replaced in this car.  I didn't buy one when I bought the pump 
and the wrench feels the fuel gauge reading wrong is a sender issue.  (I 
thought we figured out years ago that that was not the issue, but I'm 
getting old as is the car....)).

Roger

Oh, yeah....I'm thinking about life after these two Audis.  The wagon 
has 207,000 miles on it, and aside from the paint really getting thin on 
top, the car works extremely well nearly ALL of the time.  I really like 
my V8. Still and all....so I am having a mild fantasy about an Acura 
ZDX.  I'd like to see on "in the flesh" someday.  To my knowledge there 
are none in the state.  I wonder why I like this odd fish?