blue/brown temp sensor wiring loom *problem*

[aze30]

my car has some sort of additional wiring loom from blue temp and brown temp guage sensor to a relay next to the fusebox.
it seems like a proper bmw jobby but looks like it was added later as in a 'dealer fit'
does anyone know why these were added and what the purpose was?
the reason im asking is because the temp guage wasnt working before, now ive unplugged this loom and plugged the original harness directly into the sensors, it now works.
car is a 320i m20 any help would be appreciated thanks.
Azzy

[Brianmoooore]

There was a problem with some M20B20s over fuelling while they were being started from cold. Instead of fixing the problem properly, presumably by modifying the ECUs software, they came up with this bodge, which uses a relay, triggered by the starter signal, to connect a resistor in series with the 'blue' temp. sensor, making the ECU think the engine is hotter than it really is.
I have disconnected and binned every example of this that I have come across, with no ill effects as yet.

[aze30]

thanks brian....i will do the same

[aze30]

thanks brian....i will do the same

[aze30]

Problem!.....came to start it from cold and it wouldnt start just coughed and spluttered so i plugged the loom back in and it started on WOT only.
Im guessing it would benefit from an ecu change or chip?

[aze30]

Any ideas guys?

[Brianmoooore]

Check the resistance of the blue temp. sensor at the ECU plug pins stone cold, and at full working temp. (see wiki).