MAT temp vs MAT table (S

MAT temp vs MAT table (S_AUJP)

asked on the TGO but figure i will ask here too since i dont see some over there....

Ive noticed for awhile now that the data being spit out by the ecm doesnt correspond to the correct cells on the table. yesterday i spent about 30 min trying to figure out how far off it really is using the data tracing feature. had to make drastic changes in the values so the engine would respond enough for me to notice. so the issue is, say the IAT temp indicates 20*C, ill go to the corresponding cell and adjust the value at 20*C, nothing. then ill move up the the next cell which is (iirc) 44*C, adjust that value, nothing. then the next cell 56*C, adjust that and engine responds right away. so from my tinkering ive found that the indicated temperature from the datastream is about a 30*C difference from the table. this makes it difficult to fine tune since the difference is that great. would there be something wrong with the conversion in the ADX? either way i need to be able to adjust the value in the table that directly corresponds to the indicated temperature from the datastream. and help will be appreciated!

IAT, MAT ADX value is same as ECT value, both sensors read the same : X * 1.350000 + -40.000000

The way to test IAT sensoe is the same as ECT:
http://www.gearhead-efi.com/Fuel-Inj...erature+Sensor

But your thread says MAT and your question is IAT? IAT reads incoming air and at cruise should be same as ambient temps, can rise some at idle when air intake track is being heated from underhood temps. MAT reads air temp inside intake manifold so it is heated and will never match ambient temps.

Just to be clear of code, some IAT actually use a blend of ECT to come up with MAT...

As far as the table, it is just like a VE table, actual number is not what is in that cell but rather a computation of that cell and surrounding cells.

its an IAT sensor I just used the MAT to identify the table. IAT functions as normal. if i use the datatracing to adjust value in VE table, like idle for instance, ill change the cell the is highlighted. the cell that is highlighted(by the datatracing bubble) is the actual cell im adjusting, no descrepancy. for the MAT table the cell hightlighted by the datatracing bubble doesnt match up with the corresponding value in the next cell directly to the right. i have to guess and its usually about 2 cells higher up in the range. im going to try and get some pics, seems like no one understands what im asking LOL. i need to work on my engrish

*edit* since the readout from the IAT is non linear it uses the lookup table, engine off and cold, the value seems to closely match ambient air temps. now for the equation in the XDF, it uses: 1.000000*X+0.000000. does that seem right?

*edit2* just looked at the ANHT hac and found this(below). not totally sure what im looking at lol
;--------------------------------------------------
; MAT COMP Vs MAT
;
; TABLE is MAT COMP COUNTS
;--------------------------------------------------
LD7FC LDX #$87FD ; MAT COMP VS MAT TBL (^.5)
JSR LE3D0 ; 2d LOOK UP, NO OFF SET
;
LDAB #128 ;
MUL ; * 128
ADDD #$7480 ; MAT = ((MAT^.5)+233)*128
PSHB ;
PSHA ;
;
PULX ; ((MAT^.5)+233)*128, (Denom)
LDD $86DD ; CYL VOL & UNIT CONV, 159d, (LITRE)
FDIV ;
STX L006D ; SAVE INV MAT, CYL VOL & SCALING TERM
; CYL VOL/((MAT^.5)+233)*128
;
RTS ; RETURN TO MAJOR LOOP EXE

But the way the ECM/PCM uses the temps of IAT or MAT to adjust fueling is differant. Your now an IAT and cold temps going to a MAT ECM so it thinks the engine is cold and adding fuel, when the engine is not cold. It's confused!

The XDF conversion looks correct.

I did see a thread or write up awhile ago on Thirdgen.org about switching MAT to IAT, it's there take a look.

the write up instructs to use the inverse table, which is enabled since im using the IAT. ill put together a video later if i have time at work lol. its hard to explain whats really happening with a keyboard

alright heres a short video, i tried to explain it as best i could, the F-22's were flying around my house full afterburner. literally a million acres of airspace and they have to fly directly over my house, idiots. anyway, heres the video, hope i explained it well enough LOL. oh and on the way to work i was able to get the table a little closer, variations are about 5-6 BLM counts now, and idle fuel is alot better.

http://www.youtube.com/watch?v=IQUyS5wfLMo

I see what you mean and wondering if the XDF is off, which it may be but I doubt it. I think what is happening is your not taking into account Interpolation. The reading is not from one cell, it's from that cell and surrounding, so to see a change you would have to change 3 cells! It should be a smooth tranistion.

And/Or your MAT temp on dashboard is in F and the MAT in XDF is C. Are you using the MAT C value in ADX for Data Tracing?

Also I've never done the MAT to IAT swap, but normally this is a calculation to the fuel mixture in VE table, not a tuning adjustment. Look at stock MAT settings and they max out 128 counts when engine is warmed up, yours never hit 128 that I could see? Again I've never done this so just a thought...

HTH!

i understand what you mean about interpolation, but i have to skip a cell to see any results. its weird and a little frustrating at times lol. i only have the dashboard set for *F, and everything else is *C. its only like that because every metric i know is imperial. the upper portion of the table used to be 128 but in vegas heat it would start to lean out. once there is a smooth transition in temperature i plan on moving to the inverse table. im using a layout that was suggested on the TGO but theres a nice cliff in the lower load section of the VE table. im going to tweat those so its a nice smooth transition from one cell to the next. i just wanted to figure out why the MAT comp vs. MAT table is off so it makes tuning easier for others in the future. Thanks for the help!

Post your XDF and ADX with a log and I'll make the data tracing work with C...

Quote:

Originally Posted by EagleMark

Post your XDF and ADX with a log and I'll make the data tracing work with C...

Mark,

The data is already converted for *C, the *F is only for the dash. If anything id like to convert the everything to *F and tweak the table to be able to use the entire table and not half of it.

I have yet to see ANYTHING that indicates that there are ANY differences in bins and the function in the ECM of IAT or MAT. The ONLY difference I have seen over the years is the name is a mere description of where the sensor is installed, but does not indicate any functional differences.

so ive put some thought into this little problem, came up with a possible solution. If the XDF item(MAT comp vs. MAT) is edited, would it be possible to shift the right column up slightly(like two cells up) to make adjustments a bit more accurate?

Quote:

Originally Posted by Six_Shooter

I have yet to see ANYTHING that indicates that there are ANY differences in bins and the function in the ECM of IAT or MAT. The ONLY difference I have seen over the years is the name is a mere description of where the sensor is installed, but does not indicate any functional differences.

Tempretures are very differant. What INT temp makes no fueling change? What MAT temp makes no fueling change. Then match up columns. It can work. Newer stuff has IAT and ECT blend table for Dynamic Air Temp.

Quote:

Originally Posted by 34blazer

so ive put some thought into this little problem, came up with a possible solution. If the XDF item(MAT comp vs. MAT) is edited, would it be possible to shift the right column up slightly(like two cells up) to make adjustments a bit more accurate?

The reason it does not line up is data tracing is from a tempreture and the value is counts.

Quote:

Originally Posted by EagleMark

Tempretures are very differant. What INT temp makes no fueling change? What MAT temp makes no fueling change. Then match up columns. It can work. Newer stuff has IAT and ECT blend table for Dynamic Air Temp.

The reason it does not line up is data tracing is from a tempreture and the value is counts.

i understand that, the data matches up with the temp in the left column. but the right column is off, thats what im trying to fix. so when i adjust the value at a certain temp, it acutally is an adjustment to the corresponding cell. no guess work even keeping interpolation in mind.

I think I figured out why that is not accurate... MAT is counts and your data tracing with C tepm. It need a lookup table.

Code:

;* A/D degrees A/D ;* counts C Inv ;* ------- ------- --- ;* 255 -40 0 ;* 251 -30 4 ;* 250 -25 5 ;* 247 -20 8 ;* 245 -15 10 ;* 241 -10 14 ;* 237 - 5 18 ;* 231 0 24 ;* 225 5 30 ;* 218 10 37 ;* 209 15 46 ;* 199 20 56 ;* 189 25 66 ;* 177 30 78 ;* 165 35 90 ;* 152 40 103 ;* 139 45 116 ;* 126 50 129 ;* 114 55 141 ;* 102 60 153 ;* 92 65 163 ;* 81 70 174 ;* 72 75 183 ;* 64 80 191 ;* 56 85 199 ;* 50 90 205 ;* 44 95 211 ;* 39 100 216 ;* 34 105 221 ;* 30 110 225 ;* 26 115 229 ;* 23 120 232 ;* 21 125 234 ;* 18 130 237 ;* 16 135 239 ;* 14 140 241 ;* 13 145 242 ;* 12 150 243 ;* 0 200 255

ill have to figure out how to change that in the ADX, thanks!!! my weekend doesnt start until next tuesday, ill try and look into before then.

I also wanted to be able to use more of the MAT counts table for better resolution, considering my max IAT temps maybe get to 140*F or 60*C on a hot vegas day. so i was just looking at the $8D hac and at L87FD i can see all the bytes.

-------------------------------------------------------------
; MAT COMP Vs MAT
; TABLE is MAT COMP COUNTS
;-------------------------------------------------------------
; VAL BIN MAT Deg c
;----------------------------------
L87FD: .byte 0x00 ;= 0, 0 -40
.byte 0x0C ;= 12, 12 -28
.byte 0x18 ;= 24, 24 -16
.byte 0x24 ;= 36, 36 - 4
.byte 0x30 ;= 48, 48 8
.byte 0x3C ;= 60, 60 20
.byte 0x48 ;= 72, 72 32
.byte 0x54 ;= 84, 84 44
.byte 0x60 ;= 96, 96 56
.byte 0x6C ;=108, 108 68
.byte 0x78 ;=120, 120 80
.byte 0x80 ;=128, 128 92
.byte 0x80 ;=128, 128 104
.byte 0x80 ;=128, 128 116
.byte 0x80 ;=128, 128 128
.byte 0x80 ;=128, 128 140
.byte 0x80 ;=128, 128 152
;

Now could i just open up hex editor and change each byte starting at, say, -12 or 0x0c and end at 72 or 0x48? Or would that mess up the checksum? i would change the XDF and ADX to match as well.

That may confuse the ECM as well? I wouldn't mess with it, just fix the ADX...

Quote:

Originally Posted by EagleMark

That may confuse the ECM as well? I wouldn't mess with it, just fix the ADX...

understood. I need to get my feet wet and ive been wanting to change that for awhile now. Ill continue to ask around or until I become too impatient and change it anyway to find out what happens LOL.