Does anyone know how the MAP is defined and the proper conversion from volts to kPa in the subject ads? Using the attached specification (which I think is for 0D A217 Engine v1_0), the arithmetic doesn't work out right. I haven't been able to find a spec specifically for v30 $OD A217.ads.

From the attached spec:

Volts = N*5/256
kPa = (N+28.06)/2.71

The "Manifold Pressure Volts (DC)" outputs from my recent log are mostly around 10 to 13 volts. Using 11.5 volts in the above equations I get 227.62 kPa. I am completely ignorant about all this tuning stuff but I'm pretty sure this ain't right.

Maybe I've got other issues that I'm not sharp enough to recognize. There is some history in this thread: https://www.thirdgen.org/forums/tbi/...turn-idle.html but for current specifics: Rebuilt '94 4.3L TBI bored .030 over, 16196395 BJFD (switched from BJLA to accomodate the manual transmission). Using "Advanced $0D v175.xdf" and TunerPro RT.

I've also attached some compined logs. I am trying to work on my fuel tables. SOme direction would be appreciated.

 

MAP ADC converted to volts will be from 0 to 5 V min/max. Usually the ECM outputs the MAP value in ADC counts. Which can be converted to voltage or to KPa. As such:

volts = N * (5.0 / 255) Note, sometimes 5.1 is used in place of 5.0

Kpa = (N * 0.369) + 10.415 Note, sometimes 10.354 is used in place of 10.415

N being the value from the ALDL stream (MAP in ADC counts)

RBob.

 

Thanks RBob. I thought the MAP in volts should be between 0 and 5 so I am lost as to why it shows up between 10.45 and 13.64 volts in my logs. No matter how I manipulate the numbers I can't seem to come up with volts or kPA's that make sense. Do you have a guess about what I am looking at and/or how to convert to something useful?

I really hate to waste this data but I wonder if I should start over with a different defintion.

Your input is appreciated.