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trouble with coolant sensor

Posted: Sun Mar 22, 2009 8:39 pm
by floppy
First a thanks to DIY for the smokin' fast delivery of a 3.0 MS2 with 2.888. Expected two weeks and received it in one!

This is a 350 chevy with factory TBI and 8-pin HEI.

Mt is reading the coolant at around 220 degrees when it is cold( 60 degrees). The sensors are all GM and the MAT sensor is fine. I have tried several different sensors with the same results also tried to calibrate with no quality results. There is a negligible difference if I unplug the sensor???

All of the sensors I have tested are right at 4.2 ohms at 61 degrees. The MAT sensor is correct and has a voltage of 3.111, the coolant is at .196 volts?

Also the MAP sensor was reading around 150 kPa, I burned a different MSQ and it went away on the second effort. What can cause the MAP to read high.

The motor fires right up and dies but I am inclined to cure the sensor problems before going any further.

tHANKS, mARK

Re: trouble with coolant sensor

Posted: Mon Mar 23, 2009 6:47 am
by Matt Cramer
floppy wrote:First a thanks to DIY for the smokin' fast delivery of a 3.0 MS2 with 2.888. Expected two weeks and received it in one!

This is a 350 chevy with factory TBI and 8-pin HEI.

Mt is reading the coolant at around 220 degrees when it is cold( 60 degrees). The sensors are all GM and the MAT sensor is fine. I have tried several different sensors with the same results also tried to calibrate with no quality results. There is a negligible difference if I unplug the sensor???

All of the sensors I have tested are right at 4.2 ohms at 61 degrees. The MAT sensor is correct and has a voltage of 3.111, the coolant is at .196 volts?
First question: Is the CLT sensor being shared with anything else, or is it hooked just to the Megasquirt?
Also the MAP sensor was reading around 150 kPa, I burned a different MSQ and it went away on the second effort. What can cause the MAP to read high.

The motor fires right up and dies but I am inclined to cure the sensor problems before going any further.

tHANKS, mARK
Usually this would be a miscalibrated MAP sensor, but it could also be a firmware corruption issue.

Re: trouble with coolant sensor

Posted: Mon Mar 23, 2009 8:59 pm
by floppy
First question: Is the CLT sensor being shared with anything else, or is it hooked just to the Megasquirt?
Yup, caught me in a rookie move. disconnected the dash temp gauge and MS is happy.
Usually this would be a miscalibrated MAP sensor, but it could also be a firmware corruption issue.
Your msq gives a high kPa but mine is correct?

Re: trouble with coolant sensor

Posted: Tue Mar 24, 2009 4:58 am
by Matt Cramer
The Nova had a 4 bar MAP sensor on it.

Re: trouble with coolant sensor

Posted: Tue Mar 24, 2009 5:28 pm
by floppy
Actually figured that was the deal. Where is the configuration for it in TS?

Re: trouble with coolant sensor

Posted: Thu Mar 26, 2009 5:06 am
by Matt Cramer
Tools -> Sensor Calibration, like in MegaTune.