This applies to AUJP and ANHT and likely to all other $8d masks.
Just make the following changes:

ADX-Add the 16-bit Value ‘Distance Travelled’:

ADX Conversion:



XDF-ALDL Words #49 and 50-Change the addresses reported as below:
ALDL #----Current Address----New Address
49----------3130----------------3085
50----------3131----------------3086

 

You could also make it so the ecu doesn't wipe that value at key off. Would be more useful.

 

I was wondering why the distance and fuel used values in the ALDL stream are incorrect? They are used in the '90 & '91 Y body cars.

RBob.

 

Hmmm. Interesting that accum distance and fuel were OK in other masks but not in 8d. 8d accum distance (L0134) is either a GM bust because it's a 1-byte variable, or maybe they were using it for debugging and forgot to change the ALDL stream. Accum fuel (L0130) looks like a variable for debugging, because the calculation makes no sense for accum fuel. 2-byte L012E has some promise of reporting accum fuel (cumulative BPW sent to the injectors since ECM power-on), but does not appear to include adjustments for either low PW or Injector offset voltage, and the latter can be a big chunk of the final PW. Another code mystery!?

 

The accumulated distance is a roll-over counter. This needs to be taken care of in the equipment that is using that value.

The accumulated fuel value is the same, a roll over counter. The low PW and offset compensation isn't included as fuel isn't being delivered at those times. These compensations make up for dead time in the injector(s).

Note that it is three bytes of accum fuel starting at L012D. This value is multiplied by 8 then saved in L0130 (2 bytes).

RBob.

 

Correction, discovered tonight that $8D doesn't use the accumulated distance for the CIM/CCM. Instead it sends it the current MPH, along with the accumulated fuel. Not sure why as that is the method GM used on the x-fire and '85-'89 TPI cars. Worked there, maybe they slowed down the ALDL request rate. That would do it.

RBob.

 

I'm with you and understand the above + the correction.



However, you've completely lost me on this one unless what you mean is that the compensations are not in the ALDL stream. Then OK. But the Fuel Out code snippet below seems to clearly show that the 2 compensations are added to BPW and the sum is delivered to the ECM. If the injectors are not fired to deliver ALL that fuel, how is that happening? Really puzzled.

 

The injector compensation times that are added make up for the injector dead time and incorrect flow. This is the period of time where the injector has been activated but isn't (yet) spraying the full flow of fuel.

Because it is dead time and incorrect flow it isn't included in the IP fuel accumulator. Only the volume of fuel that the ECM calculated for the engine is in that value. This is why it is so important to have the correct injector compensation values.

RBob.

 

RBob, I misinterpreted what you said. To clarify, I understand dead-time, latency, lag time or whatever it's called and understand that the low PW and offset voltage compensations are provided to make up for these situations where the injectors are not flowing at their linear rate.

I read too quickly "...Isn't being delivered ..." in your reply below and interpreted that to mean the compensation fuel sent to the ECM was not being "delivered" by the injectors. That caused my confusion and "Really puzzled" comment.
"The low PW and offset compensation isn't included as fuel isn't being delivered at those times. These compensations make up for dead time in the injector(s)."
It further prompted my posting of the code showing the total fuel requirement being sent to the ECM.

So all is now good. Sorry for the confusion and thanks for your replies.