[Diesel Tech]

My reason for bring the fuel gauge into the discussion was to get people to think not argue over the fact that they are not dead nuts on. Why GM chose what to do and how to do it is up to them. Yes, the fuel gauge stay full for way to long and at 3/4 tank you will not have 3/4 tank truly in the tank. Just the same your ECT gauge will not be spot on but in GM's mind it's good enough. If you do not like it get a different gauge but it is what it is.

 

[SCCOtech]

Whoa, hold up with the attacks!

You quote information on the " Fuel Gauge ", then address my physique, then address Your core issue.

If it is OK with you, let's at least get on the Same Page @ the Same Time.

:shrug: What the hell? Dude I didn't do any of that stuff you just made up, and I don't appreciate you attacking me about it or anything else! I see where you "throw your weight around" onto other people around here and it seems to be allowed, but *I* am not gonna be your doormat! :wardude:

I agree lets get on the same page! :Thumbup: What I asked before is totally relevant to the ECT gauge discussion here, and the question was:

So which of you have actually checked to see what each degree of the motor represents on the temp gauge?

Anybody that hasn't done this checking really shouldn't be commenting on it I don't think, because all the supposition and guesswork and opinions in the world can never replace FACTS! :rockon:

 

[Guest]

Ok guys...its getting just a tad bit heated in here. Lets try to keep the discussion civil and not get personal. When information comes out that people are able to chew on, debate and continue the discussion, everybody wins.

Now...I don't know squat about GM's, but from the jist of this thread, discussions revolve around the accuracy of GM's gauges...is that correct?

FWIW...if your gauges are reading real time...ie reflecting some known number on the "normal" sweep...then you are way ahead of my Ford. My cluster is nothing more that idiot lights with a needle.

And my fuel gauge acts much in the same way...I can drive what seems to be forever with the needle above Full...but the minute that needle gets to 1/2 tank...it sure falls quick.

Carry on....

Thanks
Dave

 

[killerbee]

:shrug: What the hell? Dude I didn't do any of that stuff you just made up, and I don't appreciate you attacking me about it or anything else! I see where you "throw your weight around" onto other people around here and it seems to be allowed, but *I* am not gonna be your doormat! :wardude:

I agree lets get on the same page! :Thumbup: What I asked before is totally relevant to the ECT gauge discussion here, and the question was:

So which of you have actually checked to see what each degree of the motor represents on the temp gauge?

Anybody that hasn't done this checking really shouldn't be commenting on it I don't think, because all the supposition and guesswork and opinions in the world can never replace FACTS! :rockon:

I have to laugh. I must be one of the only folks that finds idahofox funny. Always short on words, sometimes it takes me hours to see his humor. I am sure he didn't mean to offend you. He is like me, short in the diplomacy skills, and often speaking a foreign language.

I did measure ECT voltage once upon a time to translate accuracy. Something like this.

gauge ...................actual

160 (first mark) ...100-120
185 ....................150-160
205 .....................190-210 this is the normal needle position
210 ......................210-225
230...................... 240-250
245 ..........................255+



IMO, not bad for an oem temp gauge. The biggest discrepancy is down low, during warmup. They should label that tick mark 120 instead of 160, and the whole gauge would be more "honest".

Hope that helps

 

[TheBac]

Um, guys.....I'm sorry I brought up the fuel gauge. Kinda took this thread in a whole different direction, didn't it? Oops...



I have a question, though. It was brought up in Cookesville's thread.......

Has anyone outfitted their O/H truck with more-accurate gauges and other weather-reporting devices so they get a complete picture of what's happening to- and by- the engine? Wind speed, direction, etc.......
It would almost be like a weather-station-on-wheels, I guess.

 

[Diesel Tech]

I did measure ECT voltage once upon a time to translate accuracy. Something like this.

gauge ...................actual

160 (first mark) ...100-120
185 ....................150-160
205 .....................190-210 this is the normal needle position
210 ......................210-225
230...................... 240-250
245 ..........................255+

So where did you come up with these numbers from? I own 1999, 2004 and 2006 trucks, all the coolant gauges are the same. They all work the same. First mark is 160 then there are three small marks, then a large one. Three more small then 210. Three more small, one large, three more small and 260.
If you assume the gauge to be divided evenly by the marks (6.25* per mark)you can only come up with some of the numbers you've posted. On top of that I have never had any of my trucks have the needle on any mark other than the bottom mark! Once the truck starts to warm up the needle always points in between one of the marks and moves in steps from one to the next.

If your going to solve an over heating issue you first need to get real information from real equipment, not make it up as you go. :shrug:

 

[killerbee]

These are measured numbers, against ECT sensor voltage, then converted using delphi's own part spec chart for voltage vs temp. Then compared with the analog gauge reading you see on the left. Interpolations have been made for 185 (between major tickmarks) and 205 (normal needle position in this vehicle), notwithstanding parallax error.

This was done at every stage of warmup, then past steady state heat removal, into overheat stage.

This data is over a year old, from an unreflashed 04.5 LLY.

Anyone with a predator or any real time scanner can do this for themselves.

IMO, overheating has been remedied, so for me, the discussion of gauge accuracy is mute. The worst part of the gauge IMO, is the high degree of innacuracy it has when the needle comes off the wall at 160. It leads the driver to believe that the motor is quite warm, and it is not. I don't really care about the upper range accuracy, as the DIC is quite accurate and repeatable, with triggers based on digital voltage supplied as input for PCM message and defuel actions...

 

[killerbee]

Now I have answered your question, I'll ask mine again, as it was overlooked. I am very interested in your answer.

Steve, have you been able to find evidence of stepwise ECM programing, something that would point to intentional factory programming, that makes for stepwise (gauge) movement ?

...as you have asserted, we don't just make things up as we go.

 

[Diesel Tech]

I have no dog in this debate, just need to know what was used. Since an OEM coolant or transmission gauge will not read the values you've posted I will take it for what it is worth. Just so you know the OEM gauge does not read as a linear gauge. It reads in steps. So when the gauge is in one position it will step to the next once it reaches the set point. If you were to watch the gauge on a dyno (so we can watch the gauge and not the road) as we have you would see it sits still then all at once move to the next point. On my personal trucks it seems to be about one line each movement. The problem is at the lower portion of the gauge each step is about 12* and in the middle it's about 35* per step.

Anyone that knows me knows I am a stickler when it comes to repeatable testing. You have to be if you want to learn something from the data reported. You should be able to repeat the same test over and over and get the same results and if you cannot then you need to determine why. That's the only reason I spent any time at all with the OEM gauges. Our customers report things back to us and I need to understand what they are saying and the gauges drove me nuts until I spent the time to see what was happening with them. Now they are used only as a reference point when a customer reports to us as I know what they do and do not do. To try and point out temperature changes like 182 Vs 185 just is not going to happen, just like 220 Vs 235 is not going to happen using the factory gauge in a Duramax. It gives you an indication of the area the temperature is in and that's it!

These are measured numbers, against ECT sensor voltage, then converted using delphi's own part spec chart for voltage vs temp. Then compared with the analog gauge reading you see on the left. Interpolations have been made for 185 (between major tickmarks) and 205 (normal needle position in this vehicle), notwithstanding parallax error.

Were these voltages base on the 300 ohm pullup specification or the 4K ohm specification? I suppose you already knew the ECM uses two different pullups that change the scale being used didn't you?

Since there are two post running on this I have quoted it all here for you.

How can you with any degree of accuracy say where 205 is............ you cannot as the gauge does not show it, just as you cannot for any other temperature number. I cannot either unless we instrument the engine or datalog the buss. If you spent the time to do the testing as we have done you will find just what we did. As far as Gauge calibration that is not done in the ECM but the dual ECT sensor calibration is, as is the switch point for the sensor scales. The Gauge is handled in the Dash computer. I've done the testing it appears that you have not.

 

[killerbee]

I'm not worthy

:bow: I'll quote you :

"So when the gauge is in one position it will step to the next once it reaches the set point. If you were to watch the gauge on a dyno (so we can watch the gauge and not the road) as we have you would see it sits still then all at once move to the next point. "

I have no reason to disagree with what you say you have seen, but I have never seen this behavior. stepwise fashion as you are describing. Like a quarts second hand is what I am hearing. I have never seen anything except steady fluid movement

I am just trying to learn something here.:Thumbup: Poking at me with what you perceive is lack of expertise is waste of my time. :itsdeadAll this testing "you have done" and no controverting data to dispute my claim? If you think my chart is wrong, then post what you have and lets compare them. Prove me wrong, if you think thats productive, but give something we can learn from.:hug:






:bounce :bounce :bounce :bounce :bounce :bounce

BTW, my chart was never meant to be a precise claim. It wasn't created under lab conditions, it was done to get a handle on ballpark trustworthiness of an imprecise analog gauge. As anyone can see it has a large range. The "205" you keep picking at, is an estimated analog gauge needle position. Mark calls his 203, whatever. Knock yourself out. It is good to 5 degrees at the most with head movement and parallax error alone. Do I care? No. The needle width alone is 3 degrees, and....I don't care. On an analog, I care about 20 degrees disparities. I don't care if the 12 oclock (210) position represents actual 215 degrees, or 205, or 208. I supplied a range that you will see on this vehicle. And it is "accurate" for what it is! I posted it because I think a lot of people would get use of the fact that a "160" reading, is actually only 110 in the motor. A 50 degree disparity! That is the worst part of THIS gauge IMO. Maybe yours is different. In fact the the first 2 tick marks represent an actual temperature range that is triple the 6 degrees suggested by gauge graduations. That is why it moves so slow at first, and then quickly as it approaches 210. But at around 210, it is a fairly accurate representation IMO.

I can't address your scale question, I don't know the answer, from something archived a year ago. but if you think my data is wrong, say so, but PLEASE have something in its place to claim. No drama. Prove me wrong. I'm wrong all the time.:damnit

 

[idahofox]

Some of what I believe has been over looked here, is the Core to the original post.

The ECT dampening is mathematically derived by an algorithm using the Data collected from the sensor. The gauge displays the " Mean Value " of the Data collected. It is Not an instantaneous nor even an average value of coolant temperature.

...The Gauge Does Not Lie.

​

" Mean value " is a number between the smallest and largest values of a set of quantities; the nth root of the product of n factors. The mean value of 2 and 8 ( the mean proportional between 2 and 8 ) is the root of ( 2 X 8 ) or 4.

----------





A computer can not store data in analog form, a variable resistor ( in a bridge circuit ) can not provide data in digital form. Enter the Analog/Digital ( A/D ) converter. The bridge circuit feeds the analog side of the converter, the digital side feeds data ( pulses ) to the computer.

Were these voltages base on the 300 ohm pullup specification or the 4K ohm specification? I suppose you already knew the ECM uses two different pullups that change the scale being used didn't you?

​

I have tried to understand this statement, why would we change the scale of the analog data, the EC can only manage/use digital data. Further, a " pullup " function is to prevent a bridge node from exceeding a specific value ( zero can mathematically be positive or negative ) and is not functionally a part of scaling. I am not arguing, trying to understand.

----------

I have conducted five " Test " of my OEM ECT gauge in the past few days.

The needles progression across my gauge face is fluid, without " Steps " or " Ticks ".

FWIW.

 

[Diesel Tech]

Maybe this will explain it better than I have done but the ECM uses two different pull up resistors to scale the sensor, only the ECM knows when it uses which one. The ECM then reports the temperature out on the data buss which is read by the dash computer and then converted and displayed on the analog gauge. As you can see from the charts below the reason is to gain range from the sensor for accuracy. One pull up value gives better cold readings and one gives better warm readings. So you cannot use a fixed voltage reading to know what the gauge on the dash is going to read. The bottom line is you cannot use the OEM gauge for anything other than an indication as to what the temperture range is, using it for test purposes is not valid.

AD counts Deg C Deg C
0 150 150.75
4 150 110.25
8 150 87.75
12 150 74.25
16 147.75 65.25
20 138 57
24 128.25 51.75
28 122.25 47.25
32 114.75 42.75
36 110.25 38.25
40 104.25 35.25
44 99.75 32.25
48 95.25 28.5
52 92.25 25.5
56 87.75 23.25
60 82.5 20.25
64 78 17.25
68 75 14.25
72 72 12
76 66 9
80 63 6.75
84 60.75 3.75
88 57 2.25
92 53.25 -2.25
96 48.75 -5.25
100 44.25 -7.5
104 39 -12
108 35.25 -15
112 27.75 -18.75
116 20.25 -24.75
120 12 -32.25
124 0 -40.5
128 -39.75 -40.5

 

[killerbee]

The existence of this thread, is to certify the usefulness of the gauge. Diesel Tech, I see and understand that the gauge is worthless for testing purposes. I don't think that has ever been in dispute.

It was not brought up for testing purposes, as far as I know, but could appreciate where that might be assumed, we all live in different worlds. Yours is an analytical one, as is mine at times. I would never use it solely as a reference to demonstrate improvement of a mod. I would use ECM scanning of some type, or my own temp sensors.

But most of the readers won't do that, they simply use the gauge, so for them:


Are the numbers wrong, and if so, please correct them, so the requestor has his answer.

gauge ...................actual

160 (first mark) ...100-120
185 ....................150-160
205 .....................190-210 this is the normal needle position
210 ......................210-225
230...................... 240-250
245 ..........................255+

I also realize that the rate of change has a lot to do with what we read on the gauge, a considerable lag exists when things are changing quickly.

You will have to explain this ticking gauge also. I am lost on that one. I have never seen a ticking ECT gauge, on any vehicle.

This is one dead horse. If you are not disputing the numbers, just my aquisition method, then I am done.

Thanks

 

[Diesel Tech]

All that I have been saying all thought this post is you cannot use the gauge to report improvements in coolant temperature with any degree of accuracy. You seem to want to use it, now your agreeing that it's no good. So when you refer to it as the reason the overheating is solved I just cannot buy it. If you are going to report improvements install a real set of gauges and datalog before an after results. Until you do the work properly it will be questioned, as it should be.

 

[idahofox]

Diesel Tech,

First: Let’s put this to bed, " The OEM gauges are not laboratory instruments and can not provide scientifically usable information, period ". None issue for me.

- - - - - - - - - -

Next: Is the chart in your post #32 a file from data logging, is it proprietary, if not, are there similar files some where in the public venue ?

Some additional questions if I may be permitted.

The AD counts column:
1. What is the mathematical base ?
2. If it is base 10, why does it increment by 4 ?
3. Does each line represent a sample in time ?
4. Is time synched to a computer/AD clock tick ?
5. What is the sample rate ?

The data columns:
1. I presume these annotations represent data and not formula.
2. Whereas data is not stored ( in real time ) in its analog form, was this data collected from a logging event ?
3. Does the data represent analog data ( from the sensor bridge ) or digitized data ( from the EC/buss ) ?

- - - - - - - - - -

Thank you for your patience with me. I have this large void in my gray matter I working to fill. :Thumbup: ,:thanks: .

 

[Diesel Tech]

The Data provided is from a disassemble of the code within a 2004 LLY ECM. So if you can disassemble the code you can find it too. The Column values are the values used by the ECM to generate the the temperature value that is used to be displayed. The ECM switches the pullup resitor that feeds the ECT Sensor and the A/D value is read and convertered. So if you look at an A/D Value of 72 and the ECM was useing the 4K pullup that wold be 12*C, but, if the ECM was using the 300 ohm pullup it would be 72*C. So you need to know what the ECM is doing before you can generate the ECT value. The A/D counts column is the analog to digital conveter output in counts.

In laymans terms the analog signal is converted to a digital value. The digital value is looked up in a table that assigns a value to it based upon which pullup resistor is being used. That value is then transmitted on the buss to the dash controller or anything else that's reading the buss. These are the lookup tables used for the 2004 ECM. Hope this helps you understand.

 

[idahofox]

It does and Thank You Very Much.

 

[AZMAX]

Whether you like TX or not he has some good data on his site about the gauge.

 

[idahofox]

Is that data different than what is Posted Here ? ? ? ?

I have never been to that site.

 

[AZMAX]

I think it is all new data.