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Thread: Error in my tune-$100 to find it for someone

  1. #21
    Lifetime Member 5.7ute's Avatar
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    Quote Originally Posted by joecar View Post
    My understanding: when cold the sprayed fuel takes longer to evaporate; when hot it evaporates sooner.
    That is how I understand it too Joe.
    FWIW I would be pulling timing to see if the problem goes away. Standard knock sensor settings could be incorrect for the new position of the sensors.
    I would also be triple checking ALL of my earths, these can have a tendency to only show issues when hot.
    The Tremor at AIR

  2. #22
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    Actually, I think most people agree the larger the value the sooner it fires the injector in relation to TDC.

    Recently I've read articles about firing the injector closer to TDC for emissions which does make sense. For example, fuel in a cold port is in no way going to atomize, it would just pool up big time, but firing the injector when the valve is open it would be drawn in directly without pooling up.

    I guess if the injector wiring is incorrect it should still run OK. I base this on batch fire injection and batch fire works fine.

    So I'm back to thinking it's timing, go to a dyno and watch what the timing is doing.

    Again, you can do a 5000 to 7000 RPM blast when cold?

    Lee

    230" Dragster - 2000 LS1, 02020003 Speed Density, PRC 2.5 Heads,
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  3. #23
    Lifetime Member 5.7ute's Avatar
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    Quote Originally Posted by LS1_Dragster View Post
    So I'm back to thinking it's timing, go to a dyno and watch what the timing is doing.


    Lee
    That was my thoughts from the beginning. Once ECT has increased detonation is occuring.
    Another maybe is an exhaust blockage, but I would have thought the wideband would read rich if this was the case.
    Last edited by 5.7ute; August 27th, 2009 at 04:31 PM. Reason: preignition is not detonation
    The Tremor at AIR

  4. #24
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    Quote Originally Posted by 5.7ute View Post
    Another maybe is an exhaust blockage, but I would have thought the wideband would read rich if this was the case.
    That occurred to me a long time ago because I was trying to figure out what's different between both vehicles but I ruled it out (sort of) because he said it works cold. This is why I asked twice if the car will rev to 7000RPM cold for sure, if it does then that's not the problem

    230" Dragster - 2000 LS1, 02020003 Speed Density, PRC 2.5 Heads,
    MS3 Cam 237/242 .603/.609, Vic Jr. intake, Holley 1000CFM TB,
    PowerGlide, 5000 stall converter. 8.70@154 MPH

    My Projects Homepage: http://www.horsepowerracing.com

  5. #25
    Lifetime Member 5.7ute's Avatar
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    Quote Originally Posted by LS1_Dragster View Post
    That occurred to me a long time ago because I was trying to figure out what's different between both vehicles but I ruled it out (sort of) because he said it works cold. This is why I asked twice if the car will rev to 7000RPM cold for sure, if it does then that's not the problem
    It will rev from 5000 to 6000rpm when cold. But will not when warmer. I dont think he would need to try shoot for a 7000 rpm run.
    The Tremor at AIR

  6. #26
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    I agree also with the grounds. I don't think its timing.. 24 advance is adequate for these engines.
    "All that is needed for the triumph of evil is that good men do nothing..."

  7. #27
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    Have you verified fuel pressure with a gauge while doing a run? To make sure it doesn't drop off?

  8. #28
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    Quote Originally Posted by chevy052500hd View Post
    Have you verified fuel pressure with a gauge while doing a run? To make sure it doesn't drop off?
    If it did it would show on the wideband AFR.

    His first log showed lean spikes but the second one does not.

    A puzzle for sure!

    230" Dragster - 2000 LS1, 02020003 Speed Density, PRC 2.5 Heads,
    MS3 Cam 237/242 .603/.609, Vic Jr. intake, Holley 1000CFM TB,
    PowerGlide, 5000 stall converter. 8.70@154 MPH

    My Projects Homepage: http://www.horsepowerracing.com

  9. #29
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    Quote Originally Posted by 5.7ute View Post
    It will rev from 5000 to 6000rpm when cold. But will not when warmer. I dont think he would need to try shoot for a 7000 rpm run.
    I would like to see that in a log......

    EDIT: I went back and looked at the first log and he was able to get more RPM cold, soo......I dont know! A real mystery for sure.
    Last edited by LS1_Dragster; August 28th, 2009 at 04:00 AM.

    230" Dragster - 2000 LS1, 02020003 Speed Density, PRC 2.5 Heads,
    MS3 Cam 237/242 .603/.609, Vic Jr. intake, Holley 1000CFM TB,
    PowerGlide, 5000 stall converter. 8.70@154 MPH

    My Projects Homepage: http://www.horsepowerracing.com

  10. #30
    Lifetime Member 67SS509's Avatar
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    Made some more changes today but still no better. Also added a quick and rough vid so everyone can hear it also. In the vid it sounds just like a rev limiter but in the car you can hear how erratic it is. Low and high gear run starts at frame 1007.

    One more thing that has puzzled me for a while is how perfect it holds the timing at 24* when I go WOT. I would think it would hit more timing cells then that. I keep looking at table B5912 and wondering.

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