Aldl LT1 datastream

[yoheer]

Hi. Im trying to adjust my arduino gauge
I cant get IAT data.
Trans temp and coolant works
I believe it is A274 datastream
All I get is negative 40 always.

Word 25
MATDEGND NON-DEFAULTED MAT VARIABLE
DEG C= .75N - 40
DEG F= 1.35N - 40

I don't know why but I cant get this data from the protocol

[kur4o]

IAT is byte 24, counted from zero.

If you use it as a word that might explain the odd readings.

[yoheer]

It is byte not int?
coolant and trans temps are int
upd
Oh i see my mistake. I used wrong datastream
I'll check

[yoheer]

I want to add wideband reading. Using Kur40's pcm patch with d31 or d27 pin.(eehack uses pin27. d31 in the patch description)
What datastream data should I use?

It is written Byte 36 mode1 msg1 (patch)

Is it instead of SDINMW1 input mode word 1?
This is from mode 1 msg1, 36 word
Is it correct?

[NomakeWan]

D27 is the spare unused ADC input. D31 is the ADC input for the A/C pressure sensor.

According to EEHack's definition file for $EE, the A/C Pressure input is a Byte (8 bits) at Offset 26 in a Mode 00 message (F4 00). Pin D27 input would be read as a Byte (8 bits) at Offset 54 in a Mode 00 message (F4 00).

[yoheer]

thnx, I'll check
I believe it is mode 1 msg 0 byte 55 ALDL message
and it is not used in description

[yoheer]

I get ~128 values at idle. Very similar to blm.
Is it correct? How to convert it to AFR if yes?
10-20 afr wideband

Also I have an issue with MAF
It is mode1 msg0 word47
GM/SEC = 512N/65536

If i use this formula I get 0 value
Datastream value is 200ish

[NomakeWan]

According to the EE definition file for EEHack, MAF gm/s is a Word (16 bits) at Offset 45 in Mode 00 (F4 00). The calculation you posted is correct. If your datastream value was 200, then the result should be 1.5625 g/s according to that equation. Perhaps you implemented your math function incorrectly?

Converting wideband voltage to AFR depends on your wideband O2 controller. Normally the instruction manual will give you the equation required to convert its voltage into AFR. You only have Byte resolution here since it's an 8-bit ADC, so 0V~5V is 0~255. How to convert 0~255 to X:1 AFR will depend on your Wideband controller. Check your controller's documentation.

[yoheer]

I'll check math function.

It is SLC2 Free by 14point7
This is what i found
0[v]@0.68[Lambda] linear to 5[v]@1.36[Lambda], 10[AFR] linear to 20[AFR] equivalent for gasoline

[NomakeWan]

Okay, then that sucker is incredibly simple. It's a linear equation.

If you want to display as AFR (Gasoline) instead of Lambda (any fuel), then:

AFR:1 = N*(10 / 256) + 10

For example, if N is 128 (~2.5V), then:

AFR:1 = 128*(10/256) + 10
AFR:1 = 128*(0.0390625) + 10
AFR:1 = 5 + 10
AFR:1 = 15
15:1 AFR

[yoheer]

I appreciate your help

[yoheer]

Can't make MAF work

A274 GM datastream description

ALDL MODE 1 MESSAGE 0 DATA LIST
Word #46
GP6EAFND GMP6-E NON-DEFAULTED AIRFLOW (MSB)
I get value 2 at idle
If I use math function GM/SEC = 512N/65536 then I get 0
I tried word#47 GP6EAFND+1 GMP6-E NON-DEFAULTED AIRFLOW (LSB)
~200 at idle and it decreases when pushing the pedal.

[steveo]

i dont think you're understanding 8 and 16 bit numbers very well, thats a 16 bit unsigned integer. msb and lsb.

[NomakeWan]

What steveo said. If the MSB of the 16-bit Word is 2 and the LSB of the 16-bit word is 200, then the complete value of the 16-bit word is 712. Plugging 712 into the MAF conversion equation from earlier, it comes out to 5.5625 gm/s at idle. At hot idle my '95 Corvette hovers around 7 gm/s, for comparison.

[yoheer]

Thanx guys, i've already fixed it and it works.I was trying to get data from 1 byte, not 2. Time after time.