Help.... Ls2 Cyl. 5 and 8 Multiple misfires P0300
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From: Manitowoc Wi.
Help.... Ls2 Cyl. 5 and 8 Multiple misfires P0300 Please Read all before you answer.....I tried everything I can think of.
Here's the facts: 05 LS2 GTO 6 Speed New GM Crate Motor 6000 miles
Only Mods are Cold Air Intake and Muffler Delete Stock Tune.
Swapped injectors from cylinder to cylinder, All New Coils, New Wires,
Tr55 Plugs gapped to .057", New Delco O2 sensors, Valve springs are
good, Push rods not bent, No bent valves, Leak down test is perfect,
perfect compression.
Car will miss heavily at around 1900 to 2200 rpm's on cylinders 5 and 8
only verified with HP Tuners scan. Doesn't really feel like it really and
really can't hear it in the exhaust note. Car doesn't lug or have any lack
of power??.
All the plugs look great and there is no Knock. Im thinking its gotta be
electrical? Car does Idle a little rough at times though...maybe im
paranoid though.
Here is what my possible next steps are:
1.Replace the Crank Position sensor and perform a case learn?
2. Cam Sensor??
3. Any Ideas or suggestions please feel free to share....????
Here's the facts: 05 LS2 GTO 6 Speed New GM Crate Motor 6000 miles
Only Mods are Cold Air Intake and Muffler Delete Stock Tune.
Swapped injectors from cylinder to cylinder, All New Coils, New Wires,
Tr55 Plugs gapped to .057", New Delco O2 sensors, Valve springs are
good, Push rods not bent, No bent valves, Leak down test is perfect,
perfect compression.
Car will miss heavily at around 1900 to 2200 rpm's on cylinders 5 and 8
only verified with HP Tuners scan. Doesn't really feel like it really and
really can't hear it in the exhaust note. Car doesn't lug or have any lack
of power??.
All the plugs look great and there is no Knock. Im thinking its gotta be
electrical? Car does Idle a little rough at times though...maybe im
paranoid though.
Here is what my possible next steps are:
1.Replace the Crank Position sensor and perform a case learn?
2. Cam Sensor??
3. Any Ideas or suggestions please feel free to share....????
Thread Starter
TECH Enthusiast
iTrader: (26)
Joined: Aug 2010
Posts: 567
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From: Manitowoc Wi.
After reading through hundreds of threads ect...
Driveline Vibration IE: Flywheel / driveshaft ect.... MIGHT be a good bet because it
only does it at the certain RPM's 1800 to 2200ish. Does that sound logical???
Driveline Vibration IE: Flywheel / driveshaft ect.... MIGHT be a good bet because it
only does it at the certain RPM's 1800 to 2200ish. Does that sound logical???
Try the easiest thing first - replace those two plugs - I know they are new, but it is not unheard of that a box of plugs gets dropped - seen it before... After that, I would start looking into wiring - and that can be like finding a needle in a haystack - coil and injector harnesses are where I would start looking for loose/bad connectors...
Thread Starter
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From: Manitowoc Wi.
Just replaced the plugs with 2 new ones just for *****.... still the same.
I got a cam sensor for $30 I am going to replace that this afternoon, was talking with a tech at a dealer and he said that he seen a few cam sensors that would only mess up at certain rpms? anyway its worth a shot, only $30 plus then I know its a new sensor anyway.
I got a cam sensor for $30 I am going to replace that this afternoon, was talking with a tech at a dealer and he said that he seen a few cam sensors that would only mess up at certain rpms? anyway its worth a shot, only $30 plus then I know its a new sensor anyway.
Thread Starter
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From: Manitowoc Wi.
Update:
Thought I would post the results for future searches.
Installed Cam sensor and went 70 miles in the RPM range that is was throwing the code.....and the code did not come back. Before the code would pop up every 3 to 4 seconds while cruising in that range.
Hopefully this was it....crossing fingers.
Thought I would post the results for future searches.
Installed Cam sensor and went 70 miles in the RPM range that is was throwing the code.....and the code did not come back. Before the code would pop up every 3 to 4 seconds while cruising in that range.
Hopefully this was it....crossing fingers.
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Thread Starter
TECH Enthusiast
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From: Manitowoc Wi.
The code did start coming back after 150 miles but not as much. I stopped at a GM dealer and had them perform a quick crank sensor relearn with there Tech II.
Low and behold the symptoms are totally gone. We couldnt get HP Tuners to perform the relearn for some reason?
Low and behold the symptoms are totally gone. We couldnt get HP Tuners to perform the relearn for some reason?
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