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2003 Suburban rough idle changed everything

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I have a 2003 Suburban Frankenstein yes the year that Chevy decided to use parts from everything I have changed just about everything on the truck yet I still showing random misfire code po300 my HP scanner shows a misfire in cylinder 2 and 6 only I've run out of ideas can you help
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RayVoy
RayVoy
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#2 · 52 m ago

Have you tried a compression check on those cylinders?
Ray
'09 Avalanche LTZ - 5.3 - 4x4 - Black
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Jpatch
Jpatch
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Discussion Starter · #3 · a moment ago

Yes compression was around 1:25 to 1:30 I'll go on cylinder number to it seemed to be a little erratic but if I let it crank maybe 7-8 10 times it showed 130 final as soon as you accelerate over a thousand RPM it runs like a champ it runs like a champ I can manipulate the timing and air fuel with my HP tuner and it'll run beautiful turn off the ignition go have a beer when I come back it reverts back to its old rough idle I can't figure it out I think something with timing
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I'm assuming a 5.3.

And it does sound like timing, maybe you should try a crankshaft position relearn.
 

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Two threads are always confusing, let's use the other one.

 
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