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Diesel Specialist, Formerly SSonnentag
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Discussion Starter #1
OK, lets say I crank up the Pedal Position to Desired Torque table by 15%, should I crank up the Desired Boost Levels table by 15% as well?

Obviously I probably don't want to apply a simple 15% factor to the entire tables, but in general do we want to raise boost along with torque (ie fuel)?

Thanks.
Shawn
 

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dont touch the boost tables-they are very touchy-if you raise the desired boost the target position has to be modified too-its pretty tricky-you will see an increase in boost by a couple pounds if the fuel and timing are changed
pedal position is also very touchy-be careful down low or you will have full throttle at idle
 

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If you add say 15% to the Throttle/Torque table then you will be adding fuel but maybe not 15%. Boost is something that you can adjust even without changing fuel. GM has tuned these trucks for emissions not performance and/or economy. When adjusting Boost you should find out what the max is and not go beyond that. In the B2206 table you subtract the Baro reading from the numbers and you get what the desired actual boost is. Just don't mess with the vane position tables until you can't acheive what you need with the Desired boost Levels tables. I changed mine a little and ended up with 40psi boost. That's a little high for my turbo and probably yours too.
 

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Actually if you increase the Pedal vs TQ you shouldn't need to add any boost as the boost follows the fuel rate and RPM.
 

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Diesel Specialist, Formerly SSonnentag
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Discussion Starter #6
My goal is to get my cruising EGT down. I have enough power at present for daily driving (I estimate 450 RWHP). But freeway cruising at 70 mpg has my EGT's hovering around 800-850 degrees. Just getting up to speed on the freeway will spike my EGT up to 1400 degrees without even getting on the pedal. This seems too hot to me. If I'm racing or something I expect high temps, but just a steady merging into traffic is putting me up into the red on my pyrometer. I don't like that.

So if I add boost I was thinking my temps might drop some. If adjusting the boost tables doesn't add air, what will? I keep reading that high EGT's are caused by a rich fuel condition or unspent fuel escaping the cylinders to burn on it's way out the exhaust system.
 

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Diesel Specialist, Formerly SSonnentag
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Discussion Starter #8
Cobra#3747;1590458; said:
What is your altitude?
I live at around 350 feet. I frequent -30 to 4100 feet. I rarely get up to elevations of 7000-8000 feet.
 

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Take the desired vane position table for high elevation egr On, copy and past it to the low and med alt table. Then up your desired boost tables on low and med elevation. If you hit the table for about 20% starting around 40-50 mm3 and 1200-1400 rpms, dont forget to adjust both the egr on and egr off tables. This should get the result you are looking for. At this point, you will probably want to smooth out the tables some and remove some of the highs and lows that show up for no real reason.


Or Email me your tune and I will adjust it if you want

[email protected]
 

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Let the cruising EGT run where it may. If anything decrease boost a bit would be my suggestion.

You can use the scan link to see where you are cruising and what areas to change if you so desire.
 

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If you take the B1115 table and increase the 100% 1600rpm value from 900 to 1000 then doesn't that increase the fuel volume portion of B1102 since the pulse width will be extrapolated to a larger value to make the fuel volume delivered larger for the given torqe requested? I'm just trying to understand. I don't think this is the way to adjust power but I think you can add a little power at the WOT position using this.
 

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Diesel Specialist, Formerly SSonnentag
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Discussion Starter #12
lakingslayer;1590851; said:
If you take the B1115 table and increase the 100% 1600rpm value from 900 to 1000 then doesn't that increase the fuel volume portion of B1102 since the pulse width will be extrapolated to a larger value to make the fuel volume delivered larger for the given torqe requested? I'm just trying to understand. I don't think this is the way to adjust power but I think you can add a little power at the WOT position using this.
I'm WAY up over 1000 for at least half of that table. It certainly adds power. :D
 

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Kennedy;1590730; said:
Let the cruising EGT run where it may. If anything decrease boost a bit would be my suggestion.

You can use the scan link to see where you are cruising and what areas to change if you so desire.
Decrease boost to lessen the backpressure on the engine to help reduce EGT's while cruising?
 

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Cobra#3747;1590716; said:
Take the desired vane position table for high elevation egr On, copy and past it to the low and med alt table. Then up your desired boost tables on low and med elevation. If you hit the table for about 20% starting around 40-50 mm3 and 1200-1400 rpms, dont forget to adjust both the egr on and egr off tables. This should get the result you are looking for. At this point, you will probably want to smooth out the tables some and remove some of the highs and lows that show up for no real reason.


Or Email me your tune and I will adjust it if you want

[email protected]
You seem to have some insight in to how these pcm's work, I wonder if you would mind commenting on my theory in this thread ?

http://www.dieselplace.com/forum/showthread.php?t=129164
 
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