LS2 engine power reduced/surging
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Joined: Sep 2013
Posts: 15,595
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From: Cape Coral, Florida
With the misfire possibly narrowed down to #3 cylinder it may be the coil pack (these coil packs are usually pretty bulletproof) or an injector...maybe something "mechanical" like a broken valve spring...how did you determine it was #3 ??...sometimes if no spark the PCM shuts off the injector...if you have a scan tool it's possible to see if it's spark or fuel by looking at the fuel trims...without some testing (scope and scan tool) this diagnosis is just hit or miss. without a compression gauge you can do a "clear flood crank" and listen to how the engine cranks over...should be repetitive and even sounding. Just hold the gas pedal to the floor and crank...this will disable the injectors and car won't start but only crank !!
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Joined: Feb 2017
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With the misfire possibly narrowed down to #3 cylinder it may be the coil pack (these coil packs are usually pretty bulletproof) or an injector...maybe something "mechanical" like a broken valve spring...how did you determine it was #3 ??...sometimes if no spark the PCM shuts off the injector...if you have a scan tool it's possible to see if it's spark or fuel by looking at the fuel trims...without some testing (scope and scan tool) this diagnosis is just hit or miss. without a compression gauge you can do a "clear flood crank" and listen to how the engine cranks over...should be repetitive and even sounding. Just hold the gas pedal to the floor and crank...this will disable the injectors and car won't start but only crank !!
the only time out of like 5 I got the power loss WITH the check engine light coming on that was the code I got. But it’s not coming with a check engine light any other time. I moved the packs around, to see if the problem followed but I’m not getting new other cylinder misses, and the motor is brand new from Chevy so I doubt it’s a valve. I’m thinking it’s more Throttle body maybe since the pairing of the surging issue, which is really more of a won’t drop to idle instantly when I push in the clutch it’ll linger around 1500-2000 then drop when I come to a complete stop
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,595
Likes: 4,055
From: Cape Coral, Florida
A misfire will always illuminate the MIL and if it's a constant misfire the MIL will flash. Is the car speed density tuned ??...if not disconnect the MAF sensor and see if it still surges...like I said without at least a scan tool and knowing what you're looking at it's a crapshoot !!...maybe take it back to the tuner !!
