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Thread: IDC vs fuel pressure questions

  1. 03-16-2009 #1
    b727pic
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    IDC vs fuel pressure questions

    just a little background. 2004 GTO procharged 408, Meth injection / boost referenced FPR, Mototron 60's. etc....Car is running pretty strong, just trying to fine tune my AFR and timing.

    My scan this morning showed an issue with Injector duty cycle.

    Conditions:

    IAT: 70*
    AFR: 10.02 (with meth)
    Fuel Press: 82.6 PSI
    KPA: 206.4
    RPM: 6151
    IDC: 101

    My static fuel pressure is set to 60 PSI.

    Obviously I am out of injector at these settings. My question is, do I ditch the 60's in favor of the newer 72's or whatever the latest high impedance injector is out.......or should I crank up my static pressure 10-15 PSI and retune accordingly?

    I have heard of guys pushing alot more HP than I am still running 60's, just don't know all the tuning details.....

    appreciate the input.....
    2004 GTO M6, 403, Callies, compstar, wiseco, QTP HV oil pump, QTP 2 piece timing cover, EDC custom AFR 235's, LS6 intake, P1SC-1 Procharger maxed @ 13psi, 224/232 600/600 114 EDC custom cam, JBA shortie headers (thanks California) custom boost referenced return style fuel system with surge tank, walbro 255, staged magnafuel 4303, Dual LC-1, Dual Aeroforce Interceptor gages, Nexus fP and boost gages.
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  2. 03-16-2009 #2
    redhardsupra
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    bumping up FP 25% would give you <12% more fuel. what is your AFR without meth? i think you're running out cuz you're commanding a boatload of fuel.
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  3. 03-16-2009 #3
    b727pic
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    Quote Originally Posted by redhardsupra View Post
    bumping up FP 25% would give you <12% more fuel. what is your AFR without meth? i think you're running out cuz you're commanding a boatload of fuel.
    Been awhile since I ran without Meth. looking at some past logs my IDC were around 75%-80% however that was at 170 KPA vs my current 206? I have commanded AFR of 11.5:1, my AFR with Meth is showing 10.09:1. You bring up a very good point, I was told in the past just to let the AFR go fat with the meth vs tuning for it....However I just realized that my LC-1's are programed for 10.0:1 to 18.0:1......I'll bet my AFR is extremely rich given I am up against my programming limits.

    I guess the best course of action is to simply start over without the meth and dial her back in.

    you have answered my question though, if in fact I am out of injector, sounds like I need to look into some 80's vs upping the base pressure on the 60's.

    Thanks...
    2004 GTO M6, 403, Callies, compstar, wiseco, QTP HV oil pump, QTP 2 piece timing cover, EDC custom AFR 235's, LS6 intake, P1SC-1 Procharger maxed @ 13psi, 224/232 600/600 114 EDC custom cam, JBA shortie headers (thanks California) custom boost referenced return style fuel system with surge tank, walbro 255, staged magnafuel 4303, Dual LC-1, Dual Aeroforce Interceptor gages, Nexus fP and boost gages.
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  4. 03-17-2009 #4
    Cantalope Kid
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    I was thinking the same thing. I had my injectors at 96% on a stock bottom end LS1 this past week. Realized later at WOT I was for some moron reason commanding PE to 11.0. Deetadee! Backed it down to 12.8-13.0 @ WOT. IDC = 78%.
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  5. 03-17-2009 #5
    WS6FirebirdTA00
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    I like higher fuel pressure with the bigger injectors, it is better in many ways.
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  6. 07-06-2009 #6
    Ironmancan
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    Why? Please explain?
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  7. 07-07-2009 #7
    WS6FirebirdTA00
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    That way (when using a referenced FPR) you can run a smaller injector so you do not have to worry about low pulses are lower engine speeds.
    Sulski Performance Tuning
    2000 WS6 M6 - LS6 (long block, refreshed top end), 10.8:1 CR, 90 mm ported FAST, Exo-Skel, 227/232 cam, QTP HVMC, EWP, GMMG, 9" w/4.11s
    2018 Sierra SLT 5.3L A8 - Airaid intake tube, GM Borla catback, L86 Intake/Ported TB
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