Funwithmonkeys Posted March 10 Report Share Posted March 10 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 Quote Link to comment Share on other sites More sharing options...
Vaughan Posted March 10 Report Share Posted March 10 Can you attach a copy of your tune please. Is the ECU wired piggyback to a factory ECU or standalone? Quote Link to comment Share on other sites More sharing options...
Funwithmonkeys Posted March 10 Author Report Share Posted March 10 datsun 510 march 2024.pclr It is a standalone. I have a AEM water temp gauge that is reading the same as what is showing on real dash within 2c. Quote Link to comment Share on other sites More sharing options...
Adamw Posted March 10 Report Share Posted March 10 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. Quote Link to comment Share on other sites More sharing options...
Funwithmonkeys Posted March 10 Author Report Share Posted March 10 It is a AEM 30-4402. Thee was no calc table with it so I added those 2 using a multimeter and reading the gauge. I can just add in more cells and get it to extrapolate if that is the problem. Quote Link to comment Share on other sites More sharing options...
Adamw Posted March 10 Report Share Posted March 10 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. Quote Link to comment Share on other sites More sharing options...
Funwithmonkeys Posted March 11 Author Report Share Posted March 11 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. 30-4402.pdf Quote Link to comment Share on other sites More sharing options...
Adamw Posted March 11 Report Share Posted March 11 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. Quote Link to comment Share on other sites More sharing options...
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