Just another misfire-causing wild goose chase.

[rayant4]

I'm in this same boat same setup too misfires when idling but when it going it runs fine I've replace sparkplugs and coils with good coils not the cheapos, replaced MAF sensor , every once in a while I'll get a CEL and it says catalyst system efficiency below limit bank 2 , which I think is my cat, I have a 05 v8 LS , idk what else to do tired of spending money on coils,

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[LS4me]

I'm in this same boat same setup too misfires when idling but when it going it runs fine I've replace sparkplugs and coils with good coils not the cheapos, replaced MAF sensor , every once in a while I'll get a CEL and it says catalyst system efficiency below limit bank 2 , which I think is my cat, I have a 05 v8 LS , idk what else to do tired of spending money on coils,

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That sounds like the O2 sensor.....

 

[rayant4]

That sounds like the O2 sensor.....

I've already replaced the drives side o2 sensor

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[1LoudLS]

That sounds like the O2 sensor.....

or the cat could be bad... he does have a misfire that he cant seem to get rid of.

 

[rayant4]

or the cat could be bad... he does have a misfire that he cant seem to get rid of.

But it's just a rough idle when I'm on the road it runs smooth as ever

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[1LoudLS]

a misfire is a misfire... sure there are varying severities, but unburned fuel being thrown through the motor and catching fire going through the cats is bad for them, plain and simple.

 

[joegr]

Could be dirty/clogged/sticking injector(s).