any time. let me know if you need help decifering it or getting it burned on a new chip. I use the re-writeable ones from Moates, makes life much easier than having to use a uv light to erase the ole eprom chips
Hey guys, I am wanting to put together an economy tune for the obd1 6.5. I realize most of the older fellas who began this thread are nolonger active but I am in the hopes that some of you all might have some input on this. searching online reveals nothing for these engines and tuning details so I am going at this mostly blindly.
I wanted to start with the fuel table accelerator pedal vs rpm, seeing just how much the fuel (mm^3) can be reduced without going into a too lean of a condition and still be able to lessen fuel consumption overall. below is the stock fuel table shown in TunerPro for my 95 truck. is reducing these numbers by 5% too much across the board? I'm sure all you DB2 guys know when the fuel screw has been backed out too much. as for myself, I haven't really been around a diesel engine running too lean, so I don't know what to look for!
Looking at the table, the max mm^3 fuel is 66.25 at 100% throttle and 1800 rpm, reducing that by 5% would result 62.94mm^3.
the lowest fuel rate with the first increment of the throttle (6.25%) is 6.56mm^3, this reduced by 5% would be 6.23mm^3.
a question would be weather that decrease would gain any mpg's without turning it into a 3 legged dog in a race! if 5% isn't going to change much, what would normally be good percentage for an economy tune?
I am just beginning to learn more about tuning and took this one as a personal learning hobby, but my ultimate goal is to come up with two custom tunes, the economy one and one that's a slight step up from stock for performance. Later I might try to combine the two into a single tune to have the best of both worlds.
I hope he can give me some pointers, searching hasn't revealed much on this subject. I did read an article about a "lean" running diesel and it seems it not about the fuel but looks like it point more at timing adjustments for economy or performance. I see other tables in the tune that seem to change the timing by a degree or two depending on temps as the CTS adjusts with cold or hot weather. on a gasser the CTS changes fuel. maybe the fuel table is the wrong tree to climb on for an economy aspect.
Everything being equal, changes in injection timing have more affect on MPG than fueling amount. It is the percentage of fuel burn efficiency (completion) that determines MPG. You can leave the fueling rate the same and change the point at which the fuel is injected to give it more burning time and hence a more complete burn - that produces more energy, hence power, in the stroke and resulting better MPG - up to a point where the beginning of the combustion process is too soon before TDC and it actually worsens efficiency and MPG because the combustion is now fighting the crank rotation and upward movement of the piston.