Generation III Internal Engine 1997-2006 LS1 | LS6
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Old Sep 23, 2009 | 10:08 PM
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Default bad backfire

new forged motor, bosch green top 42 injectors, comp cams 224/224, long tubes, dual breathers one on each valve cover. The car wont idle and backfires, the backfiring is probably from the low idle. reprogrammed back to stock but same thing. reprogrammed for injectors and no cookie.
I change all idle related tables to 1200, car wont idle, like it has major exhaust leak. the motor is new from the machine shop. I checked for vacuum leaks and found none. I run two driver side valve covers with no fresh air ports or pcv. I have a breather in each oil fill hole. The intake is completly capped off. Last thing i want to try is changing the crank position sensor.
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Old Sep 24, 2009 | 01:12 AM
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Make sure the coils are on right. Maybe the packs are reversed. Check the grounds, esp the back of the drivers head. Just a couple of things i've seen cause nightmares.
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Old Sep 24, 2009 | 10:06 AM
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can 98 coils be reversed, they are bolted to the valve cover. The passenger side header get super hot compared to the driver side header.
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Old Sep 24, 2009 | 11:15 PM
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Originally Posted by pdasterly
can 98 coils be reversed, they are bolted to the valve cover. The passenger side header get super hot compared to the driver side header.
If they were removed from the cover, they can be reversed. Just something to check out. Is the cam installed properly, dot to dot? The coolant sensor on the drivers head good, plug ok? Valves adjusted correctly, right pushrod length?

Just throwing things out there that could cause your issue. There are probably a few more, but I can't think of any right now.
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