my LS1 is breaking up when it hits 5k+ rpm
03-18-2011, 03:36 PM
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my LS1 is breaking up when it hits 5k+ rpm when im at wot, the car pulls hard, then breaks up at 5k rpm until it shifts (about 6k rpm)
and its only thrown a p0300 random/multiple cyl misfire code
i had a vaccum leak but fixed it.
double checked for vaccum leaks and found none
changed my wires but that did nothing
had a good set of valvesprings sitting here so i put them in but it does the same thing.
http://s222.photobucket.com/albums/d...=ls1issues.mp4
plugs/wires only have about 7k miles on them
any ideas on what might be causing it?
and its only thrown a p0300 random/multiple cyl misfire code
i had a vaccum leak but fixed it.
double checked for vaccum leaks and found none
changed my wires but that did nothing
had a good set of valvesprings sitting here so i put them in but it does the same thing.
http://s222.photobucket.com/albums/d...=ls1issues.mp4
plugs/wires only have about 7k miles on them
any ideas on what might be causing it?
Last edited by 98TADRIVER; 03-19-2011 at 12:55 PM.
03-18-2011, 04:21 PM
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alrighty, even though i have 7-8k miles on the plugs, it wouldnt hurt to buy some fresh ones 
the sucky part about living in the middle of nowhere in south jersey- 20 mins one way to the parts store lol. Ill yet ya know the results.
the sucky part about living in the middle of nowhere in south jersey- 20 mins one way to the parts store lol. Ill yet ya know the results. 
03-18-2011, 06:57 PM
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new plugs installed. still doing the same thing :/ checked fuel pressure earlier when the car was parked. 55psi with key on, 58-60 when running and when i revved it
Last edited by 98TADRIVER; 03-18-2011 at 09:14 PM.
03-18-2011, 06:58 PM
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i forgot to add- it didnt start doing this until after i put my UD pulley on. also data logged it. it wasnt pulling timing or anything, fuel trims looked good
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03-18-2011, 07:08 PM
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video of what its doing. sorry the quality isnt the best, as i took this with my cellphone and the top was off the car
listen carefully, especially around 5k rpm and it even broke up into 3rd gear
http://s222.photobucket.com/albums/d...0318011250.mp4
listen carefully, especially around 5k rpm and it even broke up into 3rd gear
http://s222.photobucket.com/albums/d...0318011250.mp4
Last edited by 98TADRIVER; 03-18-2011 at 07:18 PM.
03-18-2011, 08:29 PM
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yeah its weird, i dont know if the UD pulley was the culprit or if it was mere coincidence but its a pain in the freakin *** to do an underdrive pulley install on a c5. im certainly not looking forward to removing it to put a stock one back on :/
03-18-2011, 09:10 PM
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one of my buddys who owns a vdub said he had a p0300 code before. replaced the coilpacks and it was good to go. I thought if coil packs were going bad, it'd throw a cylinder specific misfire code and run rough thru the whole rpm range. Ive owned f bodies before and replaced coils before because of p0302 and p0304 codes. I have a spare set of coil packs laying around. i might swap em tomorrow for the hell of it
03-18-2011, 09:24 PM
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I could have sworn I've read somewhere on here before about some UD pulleys causing a knock problem. It had something to do with the rubber insulation in the pulley causing a knock and causing a misfire.
03-18-2011, 10:19 PM
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I had a similar issue on a customer's 120,000 mile TA that would cause a random misfire under load around 4-5K. I always have spare plugs and wires laying around so I threw a new wire and plug on only to find out it didn't fix it. I ended up replacing one coil and it's been fine ever since. All the times I've diagnosed misfires I've only seen a couple set a cylinder specific DTC. Normally I can pull a plug wire off and it will only set a P0300 and not a DTC related to the cylinder. Might be nice to find someone with a Tech 2 so you can look at misfire history and narrow it down to a specific cylinder.
03-18-2011, 10:44 PM
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I had a similar issue on a customer's 120,000 mile TA that would cause a random misfire under load around 4-5K. I always have spare plugs and wires laying around so I threw a new wire and plug on only to find out it didn't fix it. I ended up replacing one coil and it's been fine ever since. All the times I've diagnosed misfires I've only seen a couple set a cylinder specific DTC. Normally I can pull a plug wire off and it will only set a P0300 and not a DTC related to the cylinder. Might be nice to find someone with a Tech 2 so you can look at misfire history and narrow it down to a specific cylinder.