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sailorbob · 09-03-2005, 06:03 AM

My observations on the BASE and ALTITUDE spark tables are that from the eec-iv codes I've seen on MAF equipped cars the two tables appear to be a hang over from the pre MAF and very early MAF equipped cars that still ran BAP sensors. The code for the base spark calculation interpolates between the two tables according to barometric pressure. Now on later MAF cars the BAP sensor was dropped because there is no need for it and Ford set the tables to the same values in virtually all of the cells (I've only seen the odd couple of cells that differ in most codes and these typically only by 0.25 degrees). For tuning purposes both tables should be altered and set to the same value to avoid the interpolation shifting away from what we desire (or causing us to enter a false value to compensate).

For normally aspirated tuning, as an alternative to having to update both tables, I change the address of the ALTITUDE table within the spark table lookup routine to point to the BASE table, this means I can zero the values in the ALTITUDE table and ignore it.

09-03-2005, 06:03 AM	#3
sailorbob Junior Member Join Date: Aug 2005 Posts: 29	Re: EECV timing explained My observations on the BASE and ALTITUDE spark tables are that from the eec-iv codes I've seen on MAF equipped cars the two tables appear to be a hang over from the pre MAF and very early MAF equipped cars that still ran BAP sensors. The code for the base spark calculation interpolates between the two tables according to barometric pressure. Now on later MAF cars the BAP sensor was dropped because there is no need for it and Ford set the tables to the same values in virtually all of the cells (I've only seen the odd couple of cells that differ in most codes and these typically only by 0.25 degrees). For tuning purposes both tables should be altered and set to the same value to avoid the interpolation shifting away from what we desire (or causing us to enter a false value to compensate). For normally aspirated tuning, as an alternative to having to update both tables, I change the address of the ALTITUDE table within the spark table lookup routine to point to the BASE table, this means I can zero the values in the ALTITUDE table and ignore it.