GM Coolant temp Sensor Recalibration

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yellowlt1ta
MegaSquirt Newbie
Posts: 7
Joined: Thu Dec 17, 2009 7:56 pm

GM Coolant temp Sensor Recalibration

Post by yellowlt1ta »

I have MSII v3.57 runing on TunerStudios. I recalibrate the coolant temp sensor and turn on the car and when its hot i recalibrate it again and it shows me a very diffent temp than it did before. Is there something wrong with the sensor or am i not recomended to recalibrate it when the car is hot?

Thanks, Dave
Matt Cramer
Super Squirter
Posts: 2951
Joined: Sat Jul 03, 2004 11:35 am

Re: GM Coolant temp Sensor Recalibration

Post by Matt Cramer »

What data did you use for the sensor?
yellowlt1ta
MegaSquirt Newbie
Posts: 7
Joined: Thu Dec 17, 2009 7:56 pm

Re: GM Coolant temp Sensor Recalibration

Post by yellowlt1ta »

Matt Cramer wrote:What data did you use for the sensor?
I used the pre set data from tunerstudios. I make sure it says coolant temp sensor then i set the presets on the one that says GM and i set it to fahrenheit.
Matt Cramer
Super Squirter
Posts: 2951
Joined: Sat Jul 03, 2004 11:35 am

Re: GM Coolant temp Sensor Recalibration

Post by Matt Cramer »

Test it with the sensor in a cup of boiling water and see if you get a correct reading.
yellowlt1ta
MegaSquirt Newbie
Posts: 7
Joined: Thu Dec 17, 2009 7:56 pm

Re: GM Coolant temp Sensor Recalibration

Post by yellowlt1ta »

I will do so and get back to you with the results.
Monzsta
MegaSquirt Newbie
Posts: 3
Joined: Sun Jan 11, 2009 3:02 pm

Re: GM Coolant temp Sensor Recalibration

Post by Monzsta »

GM uses a funky dual bias resistance strategy in the ECU on the coolant temp sensor. If you are piggybacking the stock ECU and vampiring the signal the odd shift in scale is what you will see.

You must either supply the megasquirt with it's own coolant temp sensor or cut loose the factory one from the stock ECU and give the stock ECU a resistor to play with to read normal temps.
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