Coolant Temperature Sensor for CIS-E

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Hi,

My car (a 16v) has been experiencing some really bad hesitation for the
first 3 - 5 minutes of driving when started cold. I can cruise up to a
stop sign, make a complete stop, rev the engine to about 1100 and very
slowly release the clutch. The rpm then drops down to 800, the car
shudders as if shivering for about a half second, and slowly lurches
forward until about 1300 rpm when it begins to run normally. There is no
noticable power loss except below about 1300 rpm. The problem goes away
when the car heats up to the little white mark.

Lately I've also been surprised at my gas mileage. I calculated it out and
am only getting about 17 - 19 mpg. It feels like its running rich. The
exhaust is the poofy grey of an older car. I drive very efficiently,
rarely cruising above 2400 rpm. I'm not tickling the redline at every
opportunity. I should definately be getting better mileage than that.
After reading Bentley in the fuel section under CIS-E, I came to think
that maybe it was my coolant temperature sensor at fault. The sensor is
located in the block, its a single terminal, and its almost directly below
the distributor. I went outside to take a look and discovered that the oil
leak from my distributor had completely coated that whole side of the
block with both black, sooty oil and drips of somewhat runny yellow oil. I
carefully checked each connector for the thermo time switch, cold start
enrichment valve, etc. and they were all clean, non-corroded contacts.

Except for one. The coolant temperature sensor connector was not insulated
from the oil with a rubber gasket and latching connector and all that. It
was just a hard plastic-covered slide-on .250" connector and it was
drenched with oil. I used a paper towel to wipe off as much oil from the
area as I could, but I didn't have time to try cleaning the oil out of the
female connector on the wire. It was pretty clear by looking at it that if
it if it was making contact in some manner, it was doing so with a huge
jump in resistance. It took several passes over the male connector in the
block just to get it to look like metal.

Returning to Bentley, I found that the resistance of the sensor increases
as the temperature decreases. So because CIS-E richens the mixture when
the engine is cold, the resistance of the oily mess caked on there would
cause the mixture to be constantly richened, and I'd loose fuel economy,
power, acceleration, and when the engine is cold and more volatile, it
would hesitate. Makes sense, right?

Well now that I think my diagnosis is correct I have to figure out what I
should do next. I could replace the sensor and splice a new wire in with a
shiny new connector on the end. But that wouldn't solve the problem in the
long term. The oil leaking from the distributor would gum it up again and
I'd be back to square one in a few weeks. What I really need is a better
single-conductor oil-insulated connector. Either that or a lot of
electrical tape wrapped around the connection (not ideal, for more reason
than one including temperature). The best solution would be to fix my
distributor oil leak, but I can't afford a new distributor right now, let
alone a new windshield, some quality rims, euro headlights or anything
else. The engine has to come first. I could probably buy all that stuff
five times over by the amount of gas I could save by fixing this problem.

So, my question is what should I do to fix this. All ideas welcome. I
realize this is kind of an idiotic way to ask the question, but I just
want other peoples opinions.

Thanks,

-Toby

--
'87 Flash Silver Metallic Scirocco 16V

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