Davies Craig EWP - preliminary results

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It may not be that critical that its precise, it could just need to be a step in the right direction! So the controller can operate better?


DD
 
Diesel Do said:
It may not be that critical that its precise, it could just need to be a step in the right direction! So the controller can operate better?
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That's just it, the pump is designed to respond appropriately to real temperatures - if it's not getting accurate temperature information then it's going to make "bad judgements." So hopefully it will perform better when properly calibrated :).
 
Diesel Do said:
If it makes it read ten degrees hotter then the controller should be able to do its job better? Maybe?
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Yes I think so. When you think about it, it seems a bit arse about face but I think it's right. The fans have been coming on alot lately and we know that they come on when the ECU reads 104, so its possible that because the pump thinks the temp is lower (and is therefore pumping less coolant around to encourage a temp increase) then the engine is getting hotter. So it might be hot instability rather than cool instability :confused:.
 
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If you link a variable resistor (pot) across the sensor which I assume is of the PTC type and put it in a pan of boiling water. You can turn the pot until the display reads 100°C . This way you will be pretty close to within a °or 2 anyway. I'd then measure the resistance on the pot and select a fixed resistor/s to give a permanent correction!!
 
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Freelaner said:
Why didn't they make you aware that the calibration of the sensor could be an issue?
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I don't think they know, this is a relatively new tech and I don't expect they've had enough user feedback to get it perfect yet. They have updated the controller in the past and it's supposed to be much better now, so they are improving it over time.

Nodge68 said:
If you link a variable resistor (pot) across the sensor which I assume is of the PTC type and put it in a pan of boiling water. You can turn the pot until the display reads 100°C . This way you will be pretty close to within a °or 2 anyway. I'd then measure the resistance on the pot and select a fixed resistor/s to give a permanent correction!!
Click to expand...

Yep that was our plan :).

The Mad Hat Man said:
How about a 20k variable resistor?
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That's what they suggested, any particular reason for the 20K figure? I don't know all that much about these components :).

Will.
 
WLJayne said:
I got a reply from DC, they said I could attatch a 20KΩ resistor in parallel to the sensor. Ok so that's something, though surely the resistor would need to be different depending on how far out of calibration the sensor is? But hey it's something to try.

Will.
Click to expand...

Don't forget they say in parallel, not in series.
This would shunt directly across the sensor. I would imagine that 20k is a pretty high value, so as not to destroy the controller.
 
The Mad Hat Man said:
Don't forget they say in parallel, not in series.
This would shunt directly across the sensor. I would imagine that 20k is a pretty high value, so as not to destroy the controller.
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Yes they very kindly included a wiring diagram with the email - so yes basically make sure it's parallel :D!
 
WLJayne said:
Yes they very kindly included a wiring diagram with the email - so yes basically make sure it's parallel :D!
Click to expand...

If I remember correctly the total resistance in a parallel circuit is always less than the value of the lowest resistor! So you are actually lowering the value;) which means it thinks its hotter cos the value decreases with temp rise!

I need to get out more:D


DD
 
Diesel Do said:
If I remember correctly the total resistance in a parallel circuit is always less than the value of the lowest resistor! So you are actually lowering the value;) which means it thinks its hotter cos the value decreases with temp rise!
Click to expand...

Right. Gotcha. So how does that translate into us sticking bits to it, exactly?
 
WLJayne said:
I'm just trying to get my head around the 20k value, why this and not say 10k or 30k? I'm just a little baffled as to why that number seems "good." :).
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it is to do with the impedance of the sensor. (no idea what that is), but DC should know the correct value. trust em. (initially) ;)
 
They're trying to reduce the resistance! If it was in series it'd make sense cos you add the resistors together, simples. But put em in parallel it's a lot more complicated but it'll reduce the resistance by a set amount. Sooo......... Crap it makes sense to me:D


DD
 
I thought so:)
Measure the resistance of the sensor and you can calculate the resistance at any given temperature! What more do you want;)


DD
 
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