Factory gauge reading hot
#1
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I recently installed a megasquirt 2 as well as a new coolant temp sensor on my MSM. I have noticed now at 200 or so at idle the factory temp gauge reads about 3/4 to pegged.
the MS shows around 200 at idle and I can point my laser thermometer at the back housing and get a similar number.
the gauge is a different story it is constant showing pegged if I’m doing anything where the temps is over 205.
any suggestions? Maybe a bad sensor?
the MS shows around 200 at idle and I can point my laser thermometer at the back housing and get a similar number.
the gauge is a different story it is constant showing pegged if I’m doing anything where the temps is over 205.
any suggestions? Maybe a bad sensor?
#6
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The factory gauge is calibrated to the factory sender. I would replace the aftermarket sender you bought with the oem sender. In addition, if you want to run your aftermarket gauge, you can run a splice connector to run your sender inline with a radiator hose like this.
I don't know the factory hose inner diameter off hand but I am sure you can figure out what the correct size is.
I don't know the factory hose inner diameter off hand but I am sure you can figure out what the correct size is.
#7
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The factory gauge is calibrated to the factory sender. I would replace the aftermarket sender you bought with the oem sender. In addition, if you want to run your aftermarket gauge, you can run a splice connector to run your sender inline with a radiator hose like this.
https://www.amazon.com/Mishimoto-MMW...00860GFCS?th=1
I don't know the factory hose inner diameter off hand but I am sure you can figure out what the correct size is.
https://www.amazon.com/Mishimoto-MMW...00860GFCS?th=1
I don't know the factory hose inner diameter off hand but I am sure you can figure out what the correct size is.
#8
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My understanding is that you want the aftermarket gauge to be on a spearate sender than the oem one. This is because the oem sender has a specific resistance curve and the process of introducing an additional circuit (the aftermarket gauge) can cause a resistance change to what the stock gauge reads. Your best bet is to make them 2 separate systems and check again.
#9
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My understanding is that you want the aftermarket gauge to be on a spearate sender than the oem one. This is because the oem sender has a specific resistance curve and the process of introducing an additional circuit (the aftermarket gauge) can cause a resistance change to what the stock gauge reads. Your best bet is to make them 2 separate systems and check again.
The NB sensors use two different elements in the same sensor housing. One is used for the ecu temp and utilizes 2 of the pins, the other is for the gauge and utilizes the remaining pin and grounds through the housing. If the gauge is reading high then the resistance reading through that element and it's associated wiring is to low. The most likely cause for that would be the wrong sensor. It looks like NB1 and NB2 sensors don't even have the same resistance curves for that element which means they can't be interchanged. Here's a thread with some info. https://www.miataturbo.net/megasquir...-values-74383/
If you have a multimeter you can confirm this very easily. Why did you replace the sensor in the first place?
#10
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Ahh, good catch @SpartanSV If you are correct, then I misunderstood what he was saying. Either way, I think the best course of action at the present moment is to get the correct oem sender for the back of the head as step 1 and move from there.
I also think it would be good to make sure the correct sensor curve is selected in tuner studio just as a double-check.
I also think it would be good to make sure the correct sensor curve is selected in tuner studio just as a double-check.
#11
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I don't think he has an aftermarket gauge. He has the temp reading from his megasquirt and he has his factory temp gauge which shows hot at anything over a 205 reading in tunerstudio.
The NB sensors use two different elements in the same sensor housing. One is used for the ecu temp and utilizes 2 of the pins, the other is for the gauge and utilizes the remaining pin and grounds through the housing. If the gauge is reading high then the resistance reading through that element and it's associated wiring is to low. The most likely cause for that would be the wrong sensor. It looks like NB1 and NB2 sensors don't even have the same resistance curves for that element which means they can't be interchanged. Here's a thread with some info. https://www.miataturbo.net/megasquir...-values-74383/
If you have a multimeter you can confirm this very easily. Why did you replace the sensor in the first place?
The NB sensors use two different elements in the same sensor housing. One is used for the ecu temp and utilizes 2 of the pins, the other is for the gauge and utilizes the remaining pin and grounds through the housing. If the gauge is reading high then the resistance reading through that element and it's associated wiring is to low. The most likely cause for that would be the wrong sensor. It looks like NB1 and NB2 sensors don't even have the same resistance curves for that element which means they can't be interchanged. Here's a thread with some info. https://www.miataturbo.net/megasquir...-values-74383/
If you have a multimeter you can confirm this very easily. Why did you replace the sensor in the first place?
the link provided was very helpful. I will continue to read through it.
#17
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Yeah but potentially the ground voltage of the engine is lifted compared to the ground voltage of the gauge. This means the gauge sees less resitance since the voltage drop across the thermistor is less. So very plausible the missing ground strap might cause the gauge to read hot.
thanks guys. All fixed.
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