Adjusting fuel used

[rgullett83]

Hey I was curiuos if any of you LBZ tuners, have been able to correct the DIC? There is a member on Diesel Place that has a good write up for this, but unless I cant read, I have not been able to find this table to adjust. Since I tuned it the DIC fuel used, and mpg is way off. Any suggestions?

Riley

[Jasondt2001]

Good question, I'd like to know as well.

[JoshH]

No way to adjust it on the LBZ. I think the LLY and LB7 have those tables though.

[rgullett83]

yeah thats what I thought. I was hoping maybe ross would chime in saying maybe in the next update it would be possible.

Riley

[GMCfourX4]

I've been trying to correct my DIC by adjusting B0720 (Main Injection Pulse). My theory is that if I can change the injector open time to match what the DIC THINKS is being used. My truck has always been off by 2 - 2.5 gallons (DIC reads high, actual fuel consumption is lower), so I upped B0720 by 10%, and found that I went a bit too far, so I'm going to re-adjust it back down a bit. I figure I should be able to get B0720 really close, then adjust engine power using timing and B1102 (Torque Based Fuel).

Can anyone with more experience tell me if I'm heading in the right direction?

-Chris

[GMPX]

It goes out of whack if you change the main pulse table, if you need to adjust the pulse times above what GM has set as stock in table {B0720} then try just adjusting the commanded mm3 instead via {B1161 & B1177} as an example.
For example, if at 100MPa and 10mm3 the ECM is commanding a 1036uS pulse time but you want 1200uS, then try adjusting the commanded mm3 that corresponds to the matching RPM/Torque point up to 30mm3 (which happens to have 1278uS as the pulse time).
This way your fuel usage reported to the DIC will be accurate, the fuel usage unfortunately does not factor in the changes made to {B0720}.

Cheers,
Ross

[rgullett83]

Thanks, Ross I may give that a shot, if the performance is still there that would be awesome

[GMPX]

The performance can still be whatever you want.
There is just a few different ways of getting there.
1 - Change the desired torque in B1161 (as an example).
2 - Change the desired fuel rate in B1177 (as an example).
3 - Change the pulse time in B0720

The only thing is, changing 1 or 2 will affect the DIC 'correctly' and the changes will be passed through to table B0720.

Cheers,
Ross

[GMCfourX4]

I made a spreadsheet that should simplify the adjustment. It takes the actual fuel used as a percentage of the DIC's fuel usage, then adjusts the injector open time by that amount (it does take into account the "opening" time of the injector by comparing the 1mm and 2mm times). Let me know what y'all think.

-Chris

[Jasondt2001]

That's a NIFTY spreadsheet GMC. I'll have to give it a shot! Thanks for the contribution!