MAT temp vs MAT table (S_AUJP)

[34blazer]

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!

[EagleMark]

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.

[34blazer]

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

[EagleMark]

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.

[34blazer]

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

[34blazer]

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