Have a 2009 Buick
Lacrosse 3.8L that has slight oscillating power surges between 37 and 42mph, with no
driveability issues other than this one and no DTC
codes. Graphic monitoring of the engine ignition timing
with Torque software indicates oscillations between 23 and 27 degrees in precise agreement with the power surges.
Lab scope indicates Ignition Control Module (ICM) X3, X18 and camshaft signals to the ICM are within parameters.
IC timing control from the Powertrain Control Module (PCM) to the ICM appear within parameters. Has anyone
experienced this same issue and if so were you able determine a solution?