Subject	Re: OEM coolant temp sensor
Posted by	Stadsport (PHX) on September 10, 2011 at 5:36 PM
	This message has been viewed 269 times.
In Reply To	OEM coolant temp sensor posted by rojoloco (San Diego) on September 10, 2011 at 04:18 PM
Message	The problem with using the OEM sensor is that it's voltage-to-temperature relation isn't linear. Because of this, the ECU has to use a table to convert the voltage into a real temperature. So, it would probably "work" in that a gauge might move, but it will pretty much never return the right temperature... and unfortunately, since it's not linear, you can't fix it with a resistor to "offset" the reading to be correct. That might fix it at one spot, but make it further off at another spot. As you can see from the chart, most of the operating range IS pretty linear, but as soon as you get to around 200F, the scale starts becoming too stretched and the gauge wouldn't read correctly, and this is right around where you'd actually want the gauge. As far as I know, you're stuck getting an aftermarket temp sensor/sending unit for an aftermarket gauge.
Follow Ups	OEM coolant temp sensor - rojoloco (San Diego) 16:18:01 09/10/11 Re: OEM coolant temp sensor - Stadsport (PHX) 17:36:23 09/10/11 Something else I just thought of... - Stadsport (PHX) 17:57:09 09/10/11 Where did you get the graph or data from? (n/m) - Wright (Ca) 18:02:10 09/10/11 Stock 90 TT map. (n/m) - Stadsport (PHX) 00:46:06 09/11/11 I use a Techtom CMX-100 plugged into the OBD port - Got Z? 20:26:00 09/10/11 Where did you buy it from? (n/m) - rojoloco (San Diego) 21:52:32 09/10/11 I bought it from Autovation in 2003 - Got Z? 22:50:28 09/10/11
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