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Thread: Motor blew up today.....need some tuning experts in here.

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  1. #6
    Fuel Injected!
    Join Date
    Feb 2013
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    Quote Originally Posted by EagleMark View Post
    I was thinking TM too. But can't remember it ever acting this way? Lag, lean then rich?

    Can't really think of anything tune related that could do this if VE is dialed in, especially MAP and MAF?

    What happens, or happened... if you were running Open Loop?

    Bummer on the piston, but I don't think a 15 AFR lean spike during WOT caused it... unless it was some spark knock not being handled properly for a long time? Have you pulled the plugs and looked for specks/fly turds on the plugs?
    I was thinking it was the van that had the lean spikes on the upshifts but when I looked at some of the old logs, nothing. Then I opened a few early ones on the Titan and low and behold lean spike city. Its MAF only but the torque management timing retard was driving it lean. I simply added fuel in the cells used during the load transition. Worked like a charm.

    On the other hand that dual planed dry intake modified for PFI may have some strange resonance or d u namic causing it to starve some cylinder and overfeed another. Nobody really knows without seeing the OEM marine tune. I know when I had TBI on a performer rpm vortec the air/fuel ratio varied substantially cylinder to cylinder with over 200* EGT differences between cylinders. When the intake was flowed it was discovered that the runners do not flow equally at all. Some port matching and grinding helped somewhat.

    In my application the crossram L31 marine intake caused the whole tune to richen up with only a little more AE needed.
    Last edited by Fast355; 10-10-2013 at 03:14 PM.

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