Timing maps for our trucks are almost impossible to find on the web. So I made a home brew data logger. I've had some success monitoring the timing reference signals and the fuel injection solenoid on the back of the pump. This is NOT a CAN bus sniffer. I drove around with the logger and captured some data. The no load timing is pretty easy to log but full load is tricky since my truck is an automatic its hard to lug down low. The logger isn't quite fast enough to catch rapidly changing RPMs, well it can but the rpms won't be nice whole numbers on the 100's so some of the data points are missing or latent. I am noticing a jump in the timing full load advance around 2900 RPM to 3000 RPM. I'm seeing no load timing from 11.5* BTDC @ 800 rpm to about 26.5* @ 3200 rpm. Loaded it's around 12 to 20 up to 2600 rpm. Then ramps up to around 25+ at 3000. I have included some spreadsheets one is raw data and the other is some I tried to sort and filter. The APPS volts are included > 3 volts is WOT. The injection duration in degrees is also included full fuel seems to be 34 degrees (crankshaft) of injection so load is pretty much scaled to injection duration. Perhaps a spreadsheet master will chime in with some nice tables and graphs.