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Newbie here. Got a question that surely has been covered a bunch of times, but searching the posts didn't turn up what I was hunting for.

I've tried this on other forums and what I got in response were assertions, general "I'm fer it" or "I'm agin it" comments, but no serious explanations. I KNOW some here can 'splain this to me.

I'm asking because I have a chip for my '04 Duramax truck, and thought of getting one my '05 Duramax. I de-installed the chip software from the '04, but the chip wouldn't install on the '05 due to engine changes that year. Before buying a second one for the '05, I decided to try a test. A half dozen or so times I alternately installed and de-installed the chip software on the '04 and made a familiar 60 mi round trip to town and back with no load or trailer. I got the same mpg (just at 22) regardless.

Which got me to wondering. I can see how acceleration and maximum power could be varied according to software parameters, but I don't get it about mpg.

Consider the scenario driving steady 60 mpg in OD pulling 3K lb trailer. This is how 90% of my truck's miles get put on. If software settings can affect mpg in this steady-state situation and a chip has better values for the settings, then it would be worth it to to me. Otherwise not. I really only care about mpg in the engine's sweet spot rpm range. The truck has abundant power for me as it is.

On the old farm tractors I'm familiar with, the injection, ignition, and timing are purely mechanical. The pump charges the injector, the cylinder compresses the air, the injector sprays, and boom.

On these high tech diesels, what parts of the cycle that affect mpg are controlled by software values? Fuel charge (volume, pattern, timing)? Are the injectors electronically controlled? Solenoid driven? Something else?

The speed shops are quick to tell me I should buy a chip and how good it's gonna be, but none so far has had an explanation of how and why.

Can someone shed some light on this for me, in a bit of technical detail, so I have an idea whether or not the chip is a good investment for the way I drive.?

Thanks,

Frank
 

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Stupid Has The Balls
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2,515 Posts
Tuning can control timing, injector pulse width, boost, de-fueling etc How this helps a little. Once you get some one who has EFI Live they will be able to go into detail
 

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I’m sure I will get flamed for this but here goes, IMO if all you are looking for MPG then the best item for that is your right foot. IMO any programming to get better MPG at a steady throttle is only doing so by running the engine to lean which is not good for the motor.
 

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Its just a worktruck
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Tuners only add mpgs if you drive like a grandma. I got my best mpgs with stock tuning around 70 mph. The MPG display on the dash is wrong. Add a tuner and the numbers get even more skewed. All aspects of a duramax are electronically controlled, even the torque converter.

I’m sure I will get flamed for this but here goes, IMO if all you are looking for MPG then the best item for that is your right foot. IMO any programming to get better MPG at a steady throttle is only doing so by running the engine to lean which is not good for the motor.
There is no such thing as lean or rich on a diesel. They are throttled off of fuel, not air.
 
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