Code: EGR and CTS conversions

[EagleMark]

I have those notes as well. It seems someone figured out how to disable EGR with 3 values (on low vac, on high vac, and TPS%), when it should only take the Enable Temp which is where I found this issue!

Then the Coolant temp conversion issue...

[jim_in_dorris]

Okay Mark, when you have time, look at the log just before your truck dies for fueling. I think that it may be part of the EGR correction VS Vacuum VS EGR D.C. I haven't completely figured out that table, but it looks like it gets to that table with the D.C. = 0, but is assuming a D.C. of 30% If that is the case, then it takes away fuel and your truck dies. Not positive that is it yet, but preliminary look at it indicates that may be happening. LMK

[1project2many]

But in TunerPro XDF looking at:
LD299 FCB 64 ; xxC COOL, Min for CLS LP Enable
Hex is 40h, TP shows in calculated view as 64d. Is it as simple as the decimal value shown for hex is Celcius?

It's as simple as using the lookup chart you posted from the ALDL DS file.
40 hex is 64 decimal. Lookup 64 decimal on the chart and it crosses to 80 deg C.

From AFBW:
LD1B3 FCB 199 ; 20c COOL FOR EGR ENABLE (1K PU) TBL 3

From AKMJ:
LD1B3 FCB 139 ; c COOL FOR EGR ENABLE (1K PU) TBL 3 <-- 45C

From ANMW:
LD1B3 FCB 131 ; 48c COOL FOR EGR ENABLE (1k pu) TBL 3

The values all match up.

That table you listed seems a little off to go all the way to 200*C. That would be a significant difference in the conversion. ?

That table is the conversion. It could also be written as :

A/D
HEX
DEGREES

COUNTS
COUNTS
Deg C

-------
------
-------

255
FF
-40

251
FB
-30

250
FA
-25

247
F7
-20

245
F5
-15

241
F1
-10

237
ED
-5

231
E7
0

225
E1
5

218
DA
10

209
D1
15

199
C7
20

189
BD
25

177
B1
30

165
A5
35

152
98
40

139
8B
45

126
7E
50

114
72
55

102
66
60

92
5C
65

81
51
70

72
48
75

64
40
80

56
38
85

50
32
90

44
2C
95

39
27
100

34
22
105

30
1E
110

26
1A
115

23
17
120

21
15
125

18
12
130

16
10
135

14
0E
140

13
0D
145

12
0C
150

0
00
200

The additional value above the maximum temp read by the CTS (152 deg) is "padding" to complete the lookup table. Without it, in case of an error caused by unexpected incorrect resistance (think Ebay $1.99 Power Mod!), the ecm could accidentally look up a value that's actually another variable.

Since it's also non linear which end is wrong? Or both ends? As long as the middle is accurate this is what matters. How many times do you see -40 or +200 Celsius?

Neither end is wrong. The "extra" values just complete the table. And FWIW when I lived in MT I saw -40F and below regularly enough to know it shows as -43C on the scantool and it sets a CTS code since "it just can't be that cold out for that long!"

I believe it is still on in many cases where a guy turned EGR off by EGR enable temp. Wonder why you go lean? Opps, 70% of fuel because of EGR...

Which is why my notes say to use Vac and TPS values to disable EGR. But setting that table to the same values as BPW and making sure EGR can't open means fueling won't change even if ecm is commanding EGR.

[EagleMark]

It's as simple as using the lookup chart you posted from the ALDL DS file.
40 hex is 64 decimal. Lookup 64 decimal on the chart and it crosses to 80 deg C.

That explains a lot... except the numbers you used above were for Closed Loop Enable Temp.
LD299 FCB 64 ; xxC COOL, Min for CLS LP Enable
In the disassembly this is one that does not have "(1k pu) TBL 3" and the vehicle enters CL at 64C ? Not 80C as the lookup would suggest.

[EagleMark]

Now more confusion in the conversion based of AD table.

The actual conversion from a GM paper is N = (E + 40) * 256 / 192.

Not sure what N and E are?
Newer masks use 0.75000 * X + -40.000 where 75 is 192 divided by the 256

So we are back to 192 and not what the AD table3 which has temps from -40 to 200 which is 240, not 192?

Ahhh! Now I re read your post it is just padding above 152C, this is why 192 is total, 152 + the -40 = 192 and not 240? Right?

[1project2many]

the numbers you used above were for Closed Loop Enable Temp.
LD299 FCB 64 ; xxC COOL, Min for CLS LP Enable

Didn't catch that.

Not sure what N and E are?

The post says what N and E are. One is "Real world" number. Other is "engineering unit."

Now more confusion in the conversion based of AD table.The actual conversion from a GM paper is N = (E + 40) * 256 / 192.

For $42 the conversion is posted with the table. It's a lookup table and it's not linear which means this formula doesn't apply.

Newer masks use 0.75000 * X + -40.000 where 75 is 192 divided by the 256

Same thing. But as I warned, different ecm's handle CTS differently in hardware so hopping from mask to mask, ecm to ecm, maybe not such a good idea.

[1project2many]

So I was curious to see how the pay for software handled this issue. Turns out it doesn't. The CTS values that use the lookup table are not available for modification. Well, so much for that.

Can TP load multiple files to edit as one calibration? Maybe we can use a lookup table and link the CTS values to that somehow. The lookup table can be saved as a separate "segment" of the calibration and it loads each time you load the .bin file...

[EagleMark]

You can compare another bin file, use it to copy and paste, but nothing like your describing?

Can't build a lookup table because TP will only use space on bin...

Could add the AD Lookup table to Parameter comments of each parameter? Found another fool proof way is using a Patch, there's options to add XDF items in several forms, one is a Patch. I already built one for Spark Advance and BPW to be added to data stream in place of 02 cross counts and Prom ID, works sweet, no way to make a mistake (if built right) then just use it again to remove patch. This could be fool proof way to turn things on/off if we know exactly what temp/hex they turn on off.

Still does not help the actual Parameter from showing an accurate temperature, not sure it ever will? Maybe they should all be referred to look at comments to set as per AD lookup?

There is one other option that I have no idea what it's for or how to apply it, X Y function? If you right click in Parmeters you can add new XDF item and one is this x y function...

[1project2many]

That X Y function is what I was looking at. That and maybe I could get creative with referencing values elsewhere in the calibration.

The only other thing I can think of is to display the value in decimal and make dang sure there's a note visible that says "use lookup table for correct value."

[EagleMark]

The only other thing I can think of is to display the value in decimal and make dang sure there's a note visible that says "use lookup table for correct value."

Since the lookup is not in the bin, this would be only option?

[gregs78cam]

Well I just spent about 3 hours coming up with an equation, a function really, that comes pretty darn close to the lookup table you posted. First I plotted it in AutoCad, to see just what type of curve it looked like, then I started manipulating it on this page:

Function Grapher and Calculator

Try this:

(-.033x+5.1)^3-.00055x^2-.09x+65.

I will graph it on my TI-85 and trace it to see how close it really is, later when I am not so tired.

[EagleMark]

Well I don't doubt your math skills, but TunerPRo does not like that at all! Once I use it, raw hex changes to 80 and calculated turns to 69c, doesn't matter what the hex was? Take it out and hex goes back to what it was, hex should never change because of a conversion, only the calculated view should.

So I added an X to (X-.033x+5.1)^3-.00055x^2-.09x+65 and it was exactly opposite correct on AD chart, before TunerPro freaked out again?

[gregs78cam]

You say it's opposite, like if you inverted one column in the posted table? I'll have to work on it some more when I have time.

[EagleMark]

Yes, I got it to work twice and looked at the AD table, compared to what hack said and it was inverted. Then TP went weird on me again? Don't know if it's my TP, or one of the math symbols? Your conversion keeps telling it to look up at prior post! ^ LOL!

AD count was 218 which should be 10c

But it spit out 159c which is about AD count 10

[1project2many]

Greg, that's some pretty creative thinking. You can actually see the curve in TP in the .adx file. By choosing acquisition then edit definition then lookup tables and table graph. If the formula is entered into excel and plotted against the lookup table the center is close but at the ends it doesn't track as well. For a hex value of 12 the formula returns 167 and the actual temp should be 150. In fact all of the calculations are off by more than 10 degrees from 95 deg C to the top of the chart. I think the final value of 0 = 200 is throwing off the generated formula on that end. At the low end of temp 255 should equal -40 degrees and the formula returns -30. That's a fair amount of error. But, and this is a big "but," we're really close between the temps of -25 and +40 degrees so what you did put us on the right track.

Mark... Tunerpro doesn't appear to like exponential functions. It can handle the beginning of the formula ok, (-0.033 * X + 5.1) , but it chokes when I try to add ^ 3. So the solution seems easy, just make it happen manually. To replace ^3 you can do this: (-0.033 * X + 5.1)*(-0.033 * X + 5.1)*(-0.033 * X + 5.1). Same thing and it works just uses more characters to type. Looking at the rest of Greg's formula, it doesn't look like there's anything hard to duplicate like "^-.22" or "^1/2" so we can replace the next one, 0.00055*X^2, with (0.00055*X)*(0.00055*X). The rest of the math is fairly basic so the entire formula looks like this:

(-0.033 * X + 5.1)*(-0.033 * X + 5.1)*(-0.033 * X + 5.1)-(0.00055*X)*(0.00055*X)-0.09*X+65.00000

This seems to give the same values as Greg's original formula when I plotted it in Excel so at least we're on the right track.

Greg, the only request I have is can we maybe get a little closer? It might help to plot more data points and fill in some missing values in the table. I'd try but my student version of Matlab from 2002 timed out and I doubt I can get another at the same price. Here's the chart of actual temp vs calculated:

Dec.   Temp    Calculated Temp
255    -40    -30.14303088
251    -30    -24.48907949
250    -25    -23.130875
247    -20    -19.18549165
245    -15    -16.66077163
241    -10    -11.85685448
237    -5    -7.368801361
231    0    -1.198779667
225    5    4.338171875
218    10    10.05995342
209    15    16.36256143
199    20    22.15233544
189    25    26.87357165
177    30    31.43218098
165    35    35.13518638
152    40    38.6133927
139    45    41.9984557
126    50    45.76409689
114    55    49.98754647
102    60    55.3115149
92    65    60.85763814
81    70    68.39727848
72    75    75.88135942
64    80    83.66449427
56    85    92.62673901
50    90    100.188625
44    95    108.5224338
39    100    116.0905388
34    105    124.2539974
30    110    131.231531
26    115    138.6211405
23    120    144.4420738
21    125    148.4586571
18    130    154.6917862
16    135    158.9885572
14    140    163.4004221
13    145    165.6500537
12    150    167.9291057
0    200    197.651