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LBZ Practice adding fuel

Practical Diesel Tuning

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Discussion and questions related to the course Practical Diesel Tuning

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Figured I would play around with a file to get more familiar with building files. Truck is a 2006 LBZ that my friend had at his shop. Right now I am just concentrating on adding additional fuel and I had some questions. I attached the example and stock file below.

Is it good to put all the additional fuel in via the Main Injection PW table? I added 20% to the last 3 row of fuel pressure.

I left the Torque based base fuel qty alone, but I modified the driver demand table to ask for 150 ft.lbs more torque in the 100% throttle column which I believe will cause the fueling to increase. Stock the max value ask is 630.6 ft.lbs and now I am asking for a max of 780.6. I assume this will drive it to value higher in the torque based fueling table. I also see tunes where people leave driven demand stock and just increase the torque based fuel along with the pulsewidth table. One way more correct than another or just two different ways for the same results?

Attached Files
  • 2006-Chev-2500HD-6.6L-ENG-A40-Allison-20fuel-main-inject.hpt
  • Attachments may only be downloaded by paid Gold members. Read more about becoming a Gold member here.

  • 2006-Chev-2500HD-6.6L-ENG-A40-Allison-OEM-STOCK.hpt
  • Attachments may only be downloaded by paid Gold members. Read more about becoming a Gold member here.


Adding fuel via the PW table is the easiest, but least refined method. It defeats the trucks ability to maintain stoichiometric/smoke control, messes with the CP3 pump flow calculations, and skews the trucks ability to calculate the actual torque.

IF I were using that method, I would avoid adding fuel to the lower mm3 sections of map and stick to the far right 3 or 4 columns (90-120mm3) instead of the rows.

Last quick note on your throttle adjustments: Log your torque and fuel rates so you know where you're at. Making assumptions is will get off center pretty quick in this business.

Hope this useful,


So more refined method is Torque Based Fuel table?

Ask yourself, does the ECU know the following?

- The actual Torque the engine is producing

- The actual fuel rate in mm3/mg being injected

- The actual amount of air being supplied

- etc. etc.

The more of these you can answer yes to, the more refined the method.