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Thread: Question about Injector Pulse and Duty Cycle - log and tune file provided!!

  1. #1
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    Default Question about Injector Pulse and Duty Cycle - log and tune file provided!!

    Hello All,
    I've had a wideband on each bank on my TA for a couple weeks now, and during tuning, I've been noticing some really weird stuff with the read AFR's, so I looked online, and saw something about the ground offset of the LC-1's. So, I checked mine, and everything is fine in regards to my LC-1's. So, I dug further and started noticing that the injector pulse widths, and duty cycles per bank sometimes are really different, and can causes different AFR readings per bank. I do have an LS7 with stock intake, so I know about the lean condition on the passenger side bank, but it tends to swing widly along with the injector pulses that are going to that bank. Does anyone have any idea why the PCM is commanding different pulse width per bank? Its just driving me nuts trying to dial in my VE tables. I'm running COSv5, and my latest log file is provided...along with my tune file.

    Thanks!
    Adrian

    P.S. In order to OPEN the Log file, you have to change the extension BACK to .zip, and NOT .efi

    I had to zip the log file and then change the extension back inorder to upload it. Thanks!
    Attached Files Attached Files

  2. #2
    Lifetime Member jfpilla's Avatar
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    I don't see anything unusual. When you hold the TP constant it all looks steady. When you change TP there are slightly different AFR readings, but nothing that is abnormal.
    2003 red vert
    Mods:
    LS7 crate engine, wet sump, 24xx reluctor
    LPE 100mm MAF
    Vararam, cold air intake and bridge
    RPM Level 6/4L60e trans
    3.42 gears
    Yank SS3600
    1-7/8" AR headers
    Z06 exhaust
    470rwhp 437rwtq
    1/8th mi-1.526-60'-6.862-1/8th-@100.74mph

  3. #3
    Joe (Moderator) joecar's Avatar
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    Looks ok to me, left/right banks are not really very different from eac other.

    You could possibly run a little richer at higher throttle.

  4. #4
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    Well, i'm glad I finally got some other opinion. I've been stressing out about it a bit lately. Also, sometimes when I'm shifting into third just normal driving, it feels like it hits a wall for a second and then picks back up. Watching my AFR when it does this, the PCM stops sending fuel for that second (AFR 21 or so) for some reason and I can't figure out why. As far as the AFR between the two banks, is it alright that at, lets say, idle, that the AFR differs sometimes by a whole point? Like the right bank will be reading 14.5 and the left reads 13.5? I mean, my drive ability is pretty damn good for the huge cam I have (barely any bucking between 1400-1800 rpms) and I get nearly 25-28 mpg on the highway, but I just get nervous, and am working to get it as close as possible.
    JoeCar, can you shoot me an example AFR table?

    Any other suggestions about my tune? I'm running a MAF less SD tune, and I'm running 42lb SVO's, are my injector flow rates correct? Anything else that seems out of wack or crazy? Its a 427 LS7 headed motor. Sorry if I seem like such a newb, I've been tuning for almost 2 years now, but I've been in Iraq for the past year, so I'm not too confident with my tuning ability at the moment haha.

    Thanks a ton,
    Adrian Mejia

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