Aldl LT1 datastream

[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.