Defuel on LMM@WOT

B

Bondurch

New member
I have a defuel problem running WOT. I logged a number of runs at the track last night and found that on the bigger tunes I am loosing significant rail pressure. Some of the runs I logged the RP below 6000, thats freaking idle conditions. It would be great to get some experienced eyes on the log that i attached to see if I have a HP or LP fueling issue. Right now I am feel that it is LP issue and chalking it up to a dirty fass filter, it was dropping below 4 psi last night and its idling at 7psi...
 

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I checked you log, it seems to be holding fine up to 3500rpms. After that it really starts to drop off. What is you rev limit set at? What is your PW set to after 3500rpms? Have you logged it after you changed your filter?
 
Are you running stock tcm tune (shift points stock)? hows it act with the converter already locked, say a 2nd gear roll in TH mode?
 
DPC said:
I checked you log, it seems to be holding fine up to 3500rpms. After that it really starts to drop off. What is you rev limit set at? What is your PW set to after 3500rpms? Have you logged it after you changed your filter?
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Thanks for the response. I have another log after replacing the filters and I still have the defuel issue. I have noticed that FRP drop begins when the transmmission is about to shift. PW?
 
05_LLY said:
Are you running stock tcm tune (shift points stock)? hows it act with the converter already locked, say a 2nd gear roll in TH mode?
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I have adjusted shift points and disabled torque limits. The defuel does occurs when TC is locked. When I roll in at second gear the duramax fuels just fine, there is no drop in FRP. Interesting that you brought that point up. I just want to go :snoop:
 
You are reving to over 4200 rpm because you are blowing through something. I'm guessing the converter. It's not defueling because of lack of fuel but rpm limits by the look of that log.
 
I am running out the door right now to log the original tunes that I purchased. I have been tweaking here and there so maybe i have pushed some torque limits and TCM shift points. I will let you know how things go.
 
Bondurch said:
I am running out the door right now to log the original tunes that I purchased. I have been tweaking here and there so maybe i have pushed some torque limits and TCM shift points. I will let you know how things go.
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I was able to do a short run launching with 20psi. the delivered fuel pressure looks good through 1st gear then starts dropping after shifting into second. I logged the Fuel Rail Pressure voltage and noticed it is dropping after the 1->2 shift. The only change to the truck is that I lowered it back to stock height and running 32 inch tires. FYI i did not have this issue a couple of months prior when I was running 35" tires.
 

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look at the desired torque reduction? Im not big in to efi live yet but its showing its requesting allot of torque reduction
 
Here is an update on my low rail pressure issue. I have chatted with Rob and Dustin and have been assured that its not in the tune. With that information I began checking the fuel line starting from the tank working my way up to the rails. Well I ran across a leak at the T fitting for my second CP3. Here are a picture of what it looked like.. I will probably replace the rubber lines from the supply side of the filter running into the rail and the braided line running to the CP3. I'm betting that this will fix the issue!
I want to thank everybody for the assistance I just wish I could give back more.

My next post should be a 12.1 @ 115.00 mph. <----- finger crossed
 

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