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High rpm misfire

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Old Sep 5, 2012 | 12:47 AM
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Default High rpm misfire

The car is an ls2 gto with ls3 top end. At wot or near wot the car will start to misfire around 5k rpm or so. It does it about %50 of the time and does not throw a cel. I have replaced plugs and plug wires with no change. I'm not sure where to look next so any suggestions are appreciated.
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Old Sep 5, 2012 | 01:05 AM
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is it possible you're running out of fuel?.....what's the duty cycle on your injectors?
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Old Sep 5, 2012 | 02:37 AM
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Is it going lean on the Wideband? If not, close your plug gaps some. Still nothing? You have broken/weak valvespring(s)
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Old Sep 5, 2012 | 06:04 AM
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Duty cycle is in the 70's so unless its a partially clogged injector its getting plenty of fuel. Valve springs only have a little over 20k on them but I'll have to pull the valve covers and take a look
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Old Sep 5, 2012 | 11:32 AM
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Originally Posted by BPP
Duty cycle is in the 70's so unless its a partially clogged injector its getting plenty of fuel. Valve springs only have a little over 20k on them but I'll have to pull the valve covers and take a look
Again, what plugs and gap? Springs sound very plausible though, it'll break up and miss like no other with crap springs.
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Old Sep 5, 2012 | 07:56 PM
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Plugs are br6ef's gapped at .035. Springs are prc .650's with about 22k on them. Would a worn spring cause an erratic mis or would mis every time at high rpm?
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Old Sep 5, 2012 | 08:19 PM
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What is the Air/Fuel ratio?
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Old Sep 5, 2012 | 08:21 PM
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Originally Posted by BPP
Plugs are br6ef's gapped at .035. Springs are prc .650's with about 22k on them. Would a worn spring cause an erratic mis or would mis every time at high rpm?
It really depends. Typically it'll break up and pull some then break up, and fall flat on it's face. Other weaker springs will probably miss all the time. It's a good idea to check springs every 20K or so. Since dropping valves is a bad thing.
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Old Sep 5, 2012 | 08:36 PM
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I have the same issue with mine
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Old Sep 5, 2012 | 09:01 PM
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Originally Posted by Charlie@Vengeance
What is the Air/Fuel ratio?
Haven't had a chance to put it on a dyno
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