Just did a 200-mile highway drive and observed about 24mpg. I bought this truck expecting nearly double that. That made me sad. Browsed a bit and discovered that even according to the "estimates" of the EPA, the California model gets some 4mpg less than the Federal emissions one. That made me angry.
My factory repair manual mentions that the CA model has a timing retard device, but doesn't go into detail. What is this device and how do I disable it? This thread mentions a custom (non-California) injection pump having dramatically improved efficiency. Is that just due to the retarded timing, or is there something else in the pump that's essentially wasting fuel? Does this engine have any other emissions equipment?
As a sidenote, I just picked up two spare engines and an additional two spare turbos, which are the wastegated type (my stock one is non-wastegated). I would expect improved power and much improved drivability from the newer turbos, but what about fuel economy? Also, can I just hook up any old vacuum line to the wastegate actuators and have them work, or do I need to do something else to prevent overboost? I'm a newbie when it comes to any kind of FI.