Injection Timing Accuracy & Warranty Protection
The coupling design allows injection timing adjustment by rotating the drive coupling—counterclockwise to advance timing, clockwise to retard timing. As documented in Isuzu AA-4BG1T workshop manuals, the two coupling bolts are loosened to make precise timing adjustments. A worn or non-genuine coupling causes injection timing drift, poor starting, reduced power, and increased fuel consumption. Using an uncertified coupling may void your Isuzu powertrain warranty. Choose genuine to restore precise drive alignment and maintain accurate injection timing.