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Initial tune

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Hi guys and girls new tuner and this is my first question.I am trying to tune my own diesel first as if I screw it up its mine.I was wondering where you all get your initial tunes from.Is there a chart or info like add 10 percent fuel for bigger injector etc.I have a lean condition on my cummins and I have been adding fuel and adj accordingly.starts good now but way lean unless I full throttle then it bumps to 15:3 then back past 18:1.trying a big swing at it tonite but asking.Thsnk you everyone

You will probably be better to post your inguiry in the diesel section, most people do little or no diesel work.

Some general observations, though...

The timing of the injection - start to finish - can have a big affect on torque, as it's roughly the equivalent of ignition timing, and can have a detrimental affect on piston life with some engines because it can overheat some parts of the piston bowl if incorrect.

Over-rich mixtures burn hot and can result in EGTs that crack manifolds and damage the turbo's turbines.

Diesels don't have a "lean" issue, as with spark ignition engines, but I assume you're referring to a lambda of higher than 1.0?

Hi Bill

Frankly, to test the waters as a novice tuner on a CDI (I assume it is), is a bad idea. As Gord pointed out, start of injection is critical, especially on a turbocharged diesel motor.

My Lambda rule of thumb, on wide open throttle, on a street driven turbo diesel is 1.05 - 1.03 max.. Anything richer does nothing else but black smoke.

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