E37 unpredictable spark timing and lean cruise
I'm sure this is simply due to my inexperience, hoping y'all can :help2:...
Vehicle is a 2007 Cobalt running on 100% Methanol.
The setup we have here is a Dynocom Dyno, with our own internally developed software (using a Labjack for data acquisition) that controls the dyno with a PID control loop to hold the car at a specific RPM by providing a signal to the dyno's Eddy brake. I hold the throttle at a specific air flow (by monitoring the grams/cyl PID on the computer screen). We then sample the load cell output and use that to calculate power and efficiency, record that and manipulate timing to achieve maximum efficiency, and thus best mileage which is the goal of this project. The problem I am having is that I cannot seem to predictably manipulate spark advance using EFILive...the advance numbers being reported just do not correlate with the parameter file. For example I can add 4 degrees of advance at a specific RPM from .08 to .20 grams/cyl of air flow (three cells). When I run the car I will see something like the .08 air flow cell having 6 degrees more than the parameter file, and the .20 cell having 6 degrees less than the parameter file (this is very consistent, and I am not able to find a spark parameter that is causing this), and often the reported advance numbers just do not change after adding (or subtracting) timing from the parameter file (I tend to go in about 2-4 degree increments). I have (only for the sake of testing) zeroed out all of the various spark advance multipliers, so as not to effect final advance, and set the max torque reduction via spark to zero...this has had no effect.
Again I'm sure there is something simple and stupid that I'm missing, I just don't know what the heck it is!
Oh and also wanted to ask if this ECM supports lean cruise?
Thanks in "advance" (pun totally intended :grin:)
Bill
EDIT: probably worth mentioning that high octane and low octane spark tables are kept identical to each other
