Water temperature sender unable to calibrate

adamnreeves
Posts: 18
Joined: Sat Mar 01, 2008 7:06 pm

Water temperature sender unable to calibrate

Postby adamnreeves » Wed Apr 18, 2012 11:14 pm

This has been a long standing issue I have had for a while, in fact from day one. I have the Potenza branded Dash2 installed in a Westfield. All the sensors except the water temperature read correctly.

For some reason the temperature has always been out, wandering. I have replaced the sensor three times now. Tried different ones. Last one I have checked the resistance from 13 to 100 centigrade and inputted the respective voltages based on a 910ohm resistor voltage divider. Still it does not read correctly. I have even used the dash2 to read back a relative value at certain temperatures using the ECU temperature as a reference and calculated a formula based on this. Still the temperature wanders. I introduced extra grounds into the loom. I have ran a completelty new wire from the sensor to the dash. I have checked the resistor itself and all the other connections, all seems fine. I am baffled.

I presume the +5v reference voltage is applied across all analgoue inputs so if this unstable then I guess it would affect all the sensors? Could it be a faultly A-D convertor in the unit?

osborni
Posts: 497
Joined: Fri Dec 07, 2007 9:08 pm
Location: USA, Michigan

Postby osborni » Thu Apr 19, 2012 12:06 pm

How much does the sensor "wander"?. I see a ~20-30*F variance in water temp over a session on track... Depends on engine load and vehicle speed.

Where does the sensor get its voltage supply from? The dash or the vehicle? Your last sentence implies the dash....(?)

The alternative is to either build your own from a VDO (or similar) sensor and see what happens or use a three wire sensor (google LM19) and pot it into the brass sensor body.

Some parts of the engine are poorly grounded as well. Did you run a ground wire directly from the lump or metal the sensor is located in?
BMW 2000 M Coupe

Support

Support

Postby Support » Thu Apr 19, 2012 5:04 pm

Hi Adam,

If the sensor is wondering alot which is no way temperature related and you have replaced everything except the DASH, then i suspect the A to D is faulty. You could confirm this by trying a different input on the DASH.

If you would like us to take a look at the DASH please send me an email.

Kind regards,
Kieran


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