The attached log shows an anomoly that I can't seem to sort out. The issue is with the spark advance starting at frame 62. The timing goes from about 13 degrees to 7 degrees and then back again. This causes the car to buck in the middle of the RPM range. It typically happens in 3rd and 4th gear. I've followed the spark advance modifiers, but can't quite come up with the calculation that results in the final spark advance. Does anyone know the exact formula for the final spark advance on an E38 ECM? This just started happening since it has warmed up here in Houston (~88 degrees) so I'm thinking IAT modifier?
E38_0072-SPARK.efi