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temp issue


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Hey guys, 

I'm using a Atom II and I am having an issue with it not reading the correct temperature in the ECU. The Highest it will read is 77c. If I adjust my fan to turn on at anything over 77 it will never turn on. The gauge in PC link rises correctly till 77 and then just stops. if I attach my tablet with real dash I can see the temp continue to rise. Is there a setting I am missing somewhere?

thanks in advance

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Your cal table for the temp sensor only spans from 40 to 170°F, 170°F is about 77°C.  In fact with only two data points I doubt it shows correct temp at all, a temp sensor wouldnt usually be linear.

What sensor do you have?  Your temp sensor calibration will need to span the range of normal operating temperature.  


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30-4402 is an oil temp gauge.  Or do you mean just the sensor from that kit is being used?  You cant connect both an ecu and gauge to the same sensor as they will both have pull-ups that will make both read wrong.  

Sorry just looked again, it says oil/trans/water temp gauge.  I guess it comes with different faces or something.


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It comes with multiple faces and It has a analog output to go to an ecu. I ran the car from 40F to 210F and added a bunch more data points. It reads within a couple of degrees the while way. It seems to be a pretty linear output. I have contacted AEM about getting a calc table for it. Thanks for the help Adam. 


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Ploting your existing calibration gives me a Y-intercept of -35, which is coincidentally close to -32, so I suspect 0V = 0°C or -32°F.  Playing around with round numbers for the span, I reckon 5V = 150°C or 302°F fits the best.  

Your existing cal numbers in blue with my guess in orange:



But be aware, you still have a 1K pull-up on the temp inputs, so the gauge should still read correct, but the analog voltage that the ecu receives is going to be biased. That could be anything from a tiny difference to a massive difference depending on how the analog output is generated in the gauge.    

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