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Chasing PO300 Misfire-Log File Attached

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Old 07-18-2015, 04:41 PM
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Default Chasing PO300 Misfire-Log File Attached

Howdy. I've been having a misfire at all speeds and rpms in my truck. It seemingly gets worse under load. It has new (factory iridium) spark plugs and Denso O2 sensors. Fuel is 55 psi with key on/engine off and just over 60 running. I just cleaned the throttle body as well. This came out of the blue... Do y'all see any clues as to what it could be in the log file? Thanks.
-Andrew Kitchens
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File Type: efi
LS1B_0052.efi (147.5 KB, 109 views)
Old 07-18-2015, 07:13 PM
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stock or aftermarket cam?
Old 07-18-2015, 08:53 PM
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Stock cam. It's an '05 lm7. Headers, tune, converter, gears.
Old 07-18-2015, 09:03 PM
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Something is obviously very wrong there, the spark is very erratic.

Post the tune up so I can take a look at it.
Old 07-18-2015, 10:36 PM
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The tune is locked. I have an autocal, but my problem is trying to get the misfire counter pids to work on efi live scan and tune. I'm looking around for a tutorial currently.
Old 07-18-2015, 10:38 PM
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Who tuned it.
Old 07-18-2015, 10:41 PM
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Black Bear Performance. The file can't be viewed or modified.
Old 07-18-2015, 10:49 PM
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Did you check the plug wires for any burns or problems?
Old 07-19-2015, 11:02 AM
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That would narrow it down to #5 and #7 plug wire. I have Obx headers with the stupid hump... Though, they are wrapped and the wires pulled away. Thank you much for the help, sir!
Old 07-19-2015, 11:06 AM
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If the wires are touching even if they're wrapped that is a possible cause for your issue. The hump on those headers suck, I had them back in the day


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