Lower Coolant Sensor

[gottasix]

Cade..
A frequent lister, Jan just helped me out with this last week. subject
.`Misfiring 85 4kq`.
Below is what Jan sent me..

The temp sensor tells the ECU when to lean the mixture.  It starts at a
resistance of 2.5k ohms at 68degF(higher when colder), and gradually drops
to
300-500 ohms when the engine is warm.  Sounds like you're running way rich.
If the sensor is the problem, it has failed at a resistance greater than
2.5k
ohms.

Two quick things you can do:
1)  Warm up the car, remove the connector from the sensor and put a resistor
of 300-500 ohms into it.  Go drive  -- normal behaviour, problem located.
2)  Remove connector from sensor, put 2.5k ohm resistor into it.  Measure
resistance of the sensor.  Should be a minimum of 2.5k ohms.  Start car and
warm up.  Monitor sensor resistance as car warms.  Should show smooth
decline.  No decline -- further confirmation.  Replace sensor -- under $30.
You can find these at any WorldPac distributor  -- www.thepartsbin.com, etc.
Most ship free on orders >$50(order Mann oil filters).

There are other things to check, but this is a start.  Ring back if this
isn't the problem.

HTH.  Make sure you tell the list what fixed the problem.

Jan Pinkowish
'85 4ksq
Bristol, CT

Best of luck..
Jeff

----- Original Message -----
From: "Cade Carvell" <ccarvell at nbsusa.com>
To: <quattro at audifans.com>
Sent: Sunday, February 09, 2003 9:46 AM
Subject: Lower Coolant Sensor


> Hi,
>   In the quest to determine my wierd inconsistant idle problems (87
> 4KQ), I started to check sensors.
>   While I had the engine running, I pulled the conector off the lower
> coolant sending unit, and the engine exihibted very similiar issues as I
> had seen when the car acted up.  Obviously it was worse, the engie
> barely ran, dash lights started to come on and off, etc.
>   Is this normal?  I would think that the computer should go into some
> kind of closed loop, and limp.  I let the car do this for 30 seconds,
> then realizing that it would not even out.  Pluged back in the car came
> right back.
>   Since I noticed a little bit of green coloring, assuming that this is
> were my slow leak in the cooling system is, I am going to replace this
> part.
>
> But should the car die like that, or is there something else that may be
> wrong, and this just helped point it out.
>
> Thanks again everyone,
>
>
> Cade Carvell
> National Business Systems, Inc.
> 2919 West Service Road
> Eagan, MN 55121
> Office: 651-994-4400
>
>
>