Follow-up: RE: '86 4kq no wanna take gas, Capt'n

[mike mcclurg]

Bernard,

Sorry that I got this thread so late. It looks like
you have discovered essentially the same fix that I
have made to my son's car.
I disconnected the connector at the sensor and wired
in a VCR tracking control variable pot that is now
located below the dash. It only uses about a quarter
of a turn from starting to fully warm. And you are
right, you can almost tune it for fully warmed by
using the instantaneous mileage display.

Mike
--- Bernard Littau <bernardl at acumenassociates.com>
wrote:
> You might appreciate my interim kludge fix while I
> waited for the new temp
> sensor to come in.  The Bentley mentioned a 15K ohm
> test connector, so I got
> 3 4.7K ohm resistors and wired them in series, and
> used the resistors
> instead of the temp sensor as a starting point to
> run the car.  It was still
> way rich, so I added a fourth resistor.  Way worse;
> duh, it must have a
> negative temperature coefficient -- no wonder it
> hardly runs at all when you
> disconnect the temp sensor.  I went to two 4.7K ohm
> resistors, and that got
> me to the parts store and work.  On the way home I
> went to one 4.7K ohm
> resistor, and that was better but not perfect.  The
> next morning, I started
> the car with the three resistors, and drove it out
> the driveway and up our
> dirt road to the mailboxes.  There I grabbed the
> paper and went down to 1
> resistor.  I drove that way to Starbucks (10 min),
> grabbed my latte, and
> connected 2 of the 4.7K ohm resistors in parallel
> (2.35K ohm) and went to
> the part store to pick up the new temp sensor, and
> on to work.  Car ran
> great from start to finish.  Gee, I don't need a
> temp sensor, just a few
> resistors and some test clips :-)
>
> The new temp sensor must have even less than 2.35K
> ohm resistance once the
> car is fully warm, as my real-time gas mileage on
> the instrument cluster
> showed even better gas mileage than with the
> resistors in parallel.  In
> fact, it gets better mileage with the new sensor
> than it ever did before,
> which kind of confirms the sensor was bad for a long
> time.
>
> Just as a side note to a long side note: the
> real-time gas mileage display
> was showing 5.0 MPG during much of the bad periods
> when the sensor had
> failed. (5.0 is its minimum reading, so it was
> likely lower)  The MPG
> sometimes got to 6.0 or so.  Hardwired at 14.1K ohm,
> the MPG hardly got
> above 8.0, even though the car ran tolerably.  I am
> amazed at how well the
> car actually ran when it was using 3-4 times as much
> fuel as normal.


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