Results 1 to 5 of 5

Thread: Closed loop when very rich?

  1. #1
    Advanced Tuner
    Join Date
    Sep 2011
    Location
    Portland, OR
    Posts
    518

    Closed loop when very rich?

    I was tuning a 6.0 turbo 2 bar setup today. Fresh tune with SD 80lb injectors.
    It was rich and responding to VE changes. I had it in closed loop just to verify that the WB was reading correctly.
    We took a break and discussed the FPR setup which is from a 98 corvette.

    The owner had it plumbed to the intake manifold as if were vac/boost referenced. After some research, it's not that kind of FPR.

    So we checked the fuel pressure. It was 95psi at the rail!
    We unplugged one of the two parallel fuel pumps and it went to 58 psi.

    So went back to the untuned VE table and started over.

    It went back to very rich, and would not go to closed loop. Or at least the O2 wouldn't switch. Flatlined at 895mv. STFT steadily decrease to -33%. Thing is, the air fuel goes to 14.7.

    This is all at idle btw. DBW 03 Silverado starting file.

    I'm a bit lost. Is it possibly so rich the STFT have limited out causing no O2 switching?

    Spent all day on the truck, 95+ out, so we stopped there. I failed to save the log after changing the FP and seeing this behavior.

    Also, I'm not confident I have all of the Siemens Deka injector data correct. If someone could check my work, I would appreciate it.

    Ron
    Last edited by RonSSnova; 08-11-2014 at 01:15 AM.
    Y2K C5 A4 Coupe (10.78 @ 127) Cathedral port 6.2
    S476 L33 5.3 69 Nova 8.76 @ 158 Drive to the track street race car
    06 Cobalt SS bought new

  2. #2
    Senior Tuner
    Join Date
    Feb 2009
    Posts
    1,931
    Yes, you can max out stft and still be so rich as to not cycle. Not at PC so can't look at tune.

  3. #3
    Advanced Tuner
    Join Date
    Sep 2011
    Location
    Portland, OR
    Posts
    518
    Good to know. We need to get the running FP checked as well.
    Thanks!
    Ron

  4. #4
    You could probably just take your 95psi VE table that you started on, and chop it down by a specific percentage. That might get you near to what it actually needs to be at. For example:

    80# injectors @ 58psi = 92.38lb/hr
    80# injectors @ 95psi = 118.23lb/hr

    So multiplying the parts of the VE table that you have already done by 92.38/118.23= 0.781. Might get you near. ALso, I sent you a PM Ron.

  5. #5
    Advanced Tuner
    Join Date
    Sep 2011
    Location
    Portland, OR
    Posts
    518
    No progress on this. My friend had some life issues get in the way. So hopefully he will rebuild his fuel system so it runs the correct pressure, and is boost referenced. And doesn't cavitate etc.

    Jordan, where did you go?
    I've sent a couple of emails.

    Ron