Temperature gauge Calibration ref Easimap value

[Spuddy Supersport]

Hi

 

Is it possible to alter the Water Temp Guage reading to read correct to the value shown in Easimap.

In Easimap it was saying 90°C, but the guage was showing 75°C?

Any thoughts?

[Benton]

I stand to be corrected, wouldn't be the first time!  , but I thought there were separate temp sensors, one for the ecu and one for the coolant gauge?

 My gauge incidentally corresponds well at the top end of the range but reads slightly under at the lower.

[Jonathan Kay]

Yes, Sevens typically use separate sensors. Which model is yours?

Please let me know if you'd like copies of the wiring diagram.

Jonathan

[Spuddy Supersport]

Mine is a 2009 Supersport 1.6 Sigma engine.

[Jonathan Kay]

Thanks.

IIRC you should be able to see two sensors.

Would you still like the indication on the gauge to match the ECU? That should be possible with some modification to the gauge's circuit, and there are some commercial devices that might do the trick. Here's John Vine's experiment with a Spiyda Gauge Wizard in the fuel gauge system.

Jonathan

[Spuddy Supersport]

If it was a calibration within easimap i would have a go. otherwise i'll leave it alone.

Thanks for your help.

[John Vine]

I imagine that, like the Duratec, your Sigma has two water temp senders, one for the ECU and the other for the gauge.

The Spiyda is a neat little unit that reads a fuel or temp sender signal and adjusts it so that the gauge displays a "corrected" value.  It's not difficult to set up, provided you can record a range of sender values.  I don't see why it wouldn't work with your temp gauge.

I'd intended to use it to correct the woefully inaccurate fuel gauge on my Duratec.  I'd got as far as calibrating it, but my plans came to naught in the end.  The gauge reading was getting corrupted by spurious voltages (of unknown origin) in the sender circuit whenever I turned the power on.

If you're interested, I can lend you my (unused) Spiyda unit to play with.

JV 

[aerobod - near CYYC]

There is a temp sensor calibration curve that Easimap can alter in unlocked ECUs, unfortunately the Caterham standard ECU is locked and the calibration is not accessible. 15C is quite a difference, though, as the 2 sensors are usually quite close together in their location and would normally give a similar value, if everything is working correctly.

[Benton]

Guess you need an infrared thermometer to test which value being displayed is closer to the truth to start with.

[aerobod - near CYYC]

If both sensors use the most common Bosch calibration curve, then if the ECU sensor is correct a 680 ohm resistor in parallel with the gauge sensor will correct it from indicating 75C to show 90C. If the gauge sensor is correct, a 130 ohm resistor in series with the ECU sensor will correct it from 90C to show 75C. This is assuming that the problem to rectify is having better accuracy at normal operating temp, with less concern about accuracy elsewhere in the temp curve.

Bosch Calibration Curve

[Spuddy Supersport]

thanks for info, ill look into doing this

[John Vine]

That's a neat solution, James.  But shouldn't the 680 ohm resistor be in parallel rather than in series?

JV

[aerobod - near CYYC]

Well spotted John, typing too fast ahead of my thoughts there, it is in parallel to reduce the resistance, I fixed the details.