NEED HELP, LS6 with a Mystery Miss
Thread Starter
Teching In
Joined: Oct 2005
Posts: 2
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From: Scottsdale, AZ
NEED HELP, LS6 with a Mystery Miss Has anyone encountered a miss in the engine in the GEN III motors that occurs mainly when the engine is unloaded (or at least it feels that way) from idle on up. At 2200 RPMS it can be described as a chassis vibration. The check engine light is not on. I have looked at everything that I can think of. New plug wires, 3 sets of plugs, compression test was from 175 to 200 with most cylinders at 185, I re-adjusted the valves and nothing seems to change it. The engine is not noisly. When this began, the oil temp was beginning to run hotter than normal and occoasionally got near/at the 300 degree mark. Short of removing the engine for a full disassembly and inspection, does anyone have any ideas on what to look at?
Engine Mods include: Magnuson Blower w/2.8" pulley, B&B headers/cats/cat-back, Livernois Stage II heads w/1.85 Comp Cams Rockers. Everything has been on the car for the last 2 years without issues.
Engine Mods include: Magnuson Blower w/2.8" pulley, B&B headers/cats/cat-back, Livernois Stage II heads w/1.85 Comp Cams Rockers. Everything has been on the car for the last 2 years without issues.
10 Second Club
Joined: Sep 2008
Posts: 60
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From: 3rd coast
You sure its a miss? What's your data say? Pcm could be pulling timing or it could be reading a misfire bc your rotating assembly has changed..(chipped your balancer?) I have a na ls6 and I used to get lots of KR at low rpm when I was in OD, crappy gas could make random missfires, and I've been getting a lot of crappy gas lately
Has anyone encountered a miss in the engine in the GEN III motors that occurs mainly when the engine is unloaded (or at least it feels that way) from idle on up. At 2200 RPMS it can be described as a chassis vibration. The check engine light is not on. I have looked at everything that I can think of. New plug wires, 3 sets of plugs, compression test was from 175 to 200 with most cylinders at 185, I re-adjusted the valves and nothing seems to change it. The engine is not noisly. When this began, the oil temp was beginning to run hotter than normal and occoasionally got near/at the 300 degree mark. Short of removing the engine for a full disassembly and inspection, does anyone have any ideas on what to look at?
Engine Mods include: Magnuson Blower w/2.8" pulley, B&B headers/cats/cat-back, Livernois Stage II heads w/1.85 Comp Cams Rockers. Everything has been on the car for the last 2 years without issues.
Engine Mods include: Magnuson Blower w/2.8" pulley, B&B headers/cats/cat-back, Livernois Stage II heads w/1.85 Comp Cams Rockers. Everything has been on the car for the last 2 years without issues.
300...??????? Do you have a true oil temp gauge or a default on/off gauge that moved a little toward the 300 line? I'd say to check your coolant levels & flow. Do you have an oil cooler? What are the intake temps from the blower? Is the blower inner-cooled, water injection, or both? If your knock sensors are dampened because of the blower, there could be un-recorded missfires. Further, your timing may be reduced to the point where a miss-fire might go un-recorded @ low un-loaded RPM. So, what is the idle timing? What has the tuner done w/ your knock, cam, crank sensor signals to reduce blower related minor missfires?
