View Full Version : Need help with cmdfuel limiter
CS5.9
January 13th, 2016, 05:46 AM
I've been trying to get that last bit of power out of my truck on a stock fuel system. my problem has been a commanded fuel drop past 2800 rpm. If i torque on it its fine as soon as i downshift it starts to tapper off downward to 122 cmdfuel at 3150 rpm. I've read every forum in this cummins 5.9L section and have tried a ton of different things ( one at a time of course). Here is a data Log. Frame 3600 shows it well. Any help would be awesome. Thanks :)
19159
Move'n Up
January 13th, 2016, 06:09 AM
One possibility: In the upper RPM range it's hard to maintain 100% load which as that load tapers off will cause a drop in fueling.
CS5.9
January 13th, 2016, 06:34 AM
Interesting... is there any references to load in any tables? i know i can view my calculated Load on my display in my truck. What variables create the calculated load output.
Move'n Up
January 13th, 2016, 06:56 AM
Take a look at this thread
https://forum.efilive.com/showthread.php?24094-Help-with-csp5-2800rpm-fuel-issue
CS5.9
January 13th, 2016, 07:16 AM
Thanks man i have read that one over and over. ill keep digging.
Dom_c13b
January 15th, 2016, 07:03 PM
What's your rail pressure at in the upper rpms? You might have to have full fueling down in the 120mm^3 range in order for it to keep full fuel at a lower rail pressure. You might also try and tweek the current conversion table a bit to keep rail up in the higher load areas. I've had a truck startpulling fuel due to rail not keeping up and was able to get full fuel by doing this.
CS5.9
January 15th, 2016, 07:22 PM
Between 155-165 mpa. I found what was pulling my commanded fuel down it was a pid rpm limiter. Apparently even with all the pids disabled the rpm limiter in the pid section was still pulling fuel some how. I got full fuel now to about 3400 rpm but after that it starts pulling fuel slowly agian all the way up to 4200rpm. Guess I'll just keep data logging.
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