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· Junior Member
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What KB has posted in text is correct or very close, however the cloak pulled over the eyes of the end user isnt represented well until you graph it.

This is the result of someone else's work.
Here is a graphical representation ECM Calculated ECT vs. Factory ECT movement.
 

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A "dumbed down" operating temp range on the gauge seems to be common for most car manufacurers. I work with Honda/Acura everyday and have seen plenty of times a gauge reading of what would appear to be normal really be 20 or more degrees from it, positive and negative. Their gauge is very vague, not giving numbers just a range. It will be a 90* sweep gauge with cold being horizontal and hot vertical with a red dash. The gauge value and the ECM value are taken from two different sensors in the same location. A picture courtesy of American Honda and a few of my scribbles.
 

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I imagine it is normal for manufacturers to do this. They don't want customers in complaining about "normal conditions". I guess it is just a bit unethical to freeze a guage in 1 position for 30*, it is my opinion that some degree of dampining is ok, but 30* seems a bit much.

I used to work with some very sensitive equipment that monitered down to parts per trillion and you had to smooth the trend or it would jump all over the place (within the accuracy of the instrument) and engineers would freek ("it moved 80 PPT, why"? "Because it is accurate to +/- 100 PPT"). Depending on the freek himself, we would change it to average somewhere between 1-10 of the last samples.
 

· Senior Member
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It appears that 200 degrees indicated on the OEM gauge is actually a range; 190 to 215 degrees.

Two questions:

1. Does the ECM provide accurate values, but the software associated with the guage represents values as indicated?

2. If so, is it possible to reprogram the software associated with the guage to represent accurate values; if not with EFI Live; by other means?
 

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The ECM will report the temp as accurate as it measures it, meaning, if the sender itself is not spot on (resistance vs temp) then the ECM will not be spot on (refer to Steve's table posted earlier to see why).

The cluster could be 100% correct, however, it's the needle movement calibration that can be wrong, or as manufacturers call it, within specification :sly:

I've re calibrated the speedo needle on my LS1 car because above 70MPH GM got a little excited, so when you were doing say 90MPH, the needle sat at 97MPH and as it goes faster it gets worse.

Cheers,
Ross
 

· BUG JUICER and
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1,256 Posts
Fwiw

Article

"Incorrect water temperature: Here we have a situation where the water temperature can differ up to 15ºC and the temperature gauge in the vehicle will not move from the normal position. This is how the cars are built ."
 

· BUG JUICER and
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1,256 Posts
Fwiw

Article

"Incorrect water temperature: Here we have a situation where the water temperature can differ up to 15ºC and the temperature gauge in the vehicle will not move from the normal position. This is how the cars are built ."

15 C=27 F
 
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