Originally Posted by
Jim P
Again, boost timing table does NOT get used UNLESS it?s final output value is greater than the air density table the ECM would otherwise be using.
If the ECM would be using air density table 1 and at a given point it would be commanding 2*BTDC but at the same given point in the boost correction table the commanded timing is 8*BTDC(assume multiplier table set at a value of 1 across the board for simplicity sake), the ECM will not use air density table 1, it will use boost correction table and give that commanded output of 8*BTDC from the boost correction table.
Almost everything in the 5.9 ECM?s for how the ECM decides to use which table, air density tables or correction tables, is set to MAX WINS. If the boost correction table is set so no matter what the final output from the boost correction table and it?s multiplier table is less than what it would be from the air density table selected by the ECM, the ECM could care less about the boost correction table, no matter what you set it at so long as it?s final output is less than what the air density table would put out, it will have zero effect on final main timing. The moment the final value from the boost correction table and its multiplier table becomes greater than what it would be from the selected air density table, the boost correction table becomes your ?main? timing table if that?s what you want to call it. There is no ?main timing table, there are multiple timing tables for a multitude of conditions and factors for their different purposes. There are parameters in the ECM that defines how all these different tables get chosen for different conditions and factors. Like in the 04.5-07 ECM, air density table 4 is used for very low air density conditions AND when the engine is in protection mode.