LS3 P0300 Code Cant Figure Out
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LS3 P0300 Code Cant Figure Out I have a 2008 corvette with a ls3 that i bought with a p0300 code and haven’t been able to figure out the problem. all cylinders are misfiring only at idle , but doesn’t misfire under load. the car also has no loss of power and never overheats. just had a very slight shake at idle but can barely feel it. here’s a list of things i have checked / replaced
-passed compression test
-passed leak down test
-passed vacuum leak test
-fuel pressure is good
-catalytic converters are good
-all fuel injectors are working properly
-new fuel pump
-new spark plugs and spark plug wires
-new coil packs
-new camshaft sensor
-new oem cam
-new maf sensor
-new map sensor
-new crankshaft sensor
-new valve springs
-previous owner replaced o2 sensors (all parts he had put on car were not oem or very cheap like coil packs , spark plug wires)
i obviously shotgunned a lot of parts on this car but have two questions on what i should do next
i have not done a camshaft relearn before or after installing new cam so should i take it to a shop to do that? could that possibly be the problem?
my other question is if i just upgrade to a stage 2 cam and get it tuned , would that get rid of the check engine light for the misfire? that’s the only thing i can think of to do if not the cam relearn.
also i can’t ask the previous owner what he did to the car or anything cuz he blocked me after selling lol
-passed compression test
-passed leak down test
-passed vacuum leak test
-fuel pressure is good
-catalytic converters are good
-all fuel injectors are working properly
-new fuel pump
-new spark plugs and spark plug wires
-new coil packs
-new camshaft sensor
-new oem cam
-new maf sensor
-new map sensor
-new crankshaft sensor
-new valve springs
-previous owner replaced o2 sensors (all parts he had put on car were not oem or very cheap like coil packs , spark plug wires)
i obviously shotgunned a lot of parts on this car but have two questions on what i should do next
i have not done a camshaft relearn before or after installing new cam so should i take it to a shop to do that? could that possibly be the problem?
my other question is if i just upgrade to a stage 2 cam and get it tuned , would that get rid of the check engine light for the misfire? that’s the only thing i can think of to do if not the cam relearn.
also i can’t ask the previous owner what he did to the car or anything cuz he blocked me after selling lol
Thread Starter
Teching In
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the shop i took it to did the vaccum leak test by smoking the car , and they told me all the fuel injectors were fluctuating properly. i also myself disabled each fuel injector on a scanner one by one to make sure it wasn’t one of them being bad
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From: Ann Arbor, MI
Misfire is detected by measuring the "evenness" of the ignition pulses as supplied by the crank sensor. So yes, cam lope could trigger a P0300, as can a high stall tiorque converter. Misfire sensitivity can be reduced in the tune and is often necessary after performance mods.
In another current thread the OP had no-start problems with 4 new crank sensors until he bought one from the dealer. From supplied pictures it was evident that Amazon was selling FAKE GM/ACDelco parts because the logo on the package was wrong. Not saying your crank sensor is bad, but there have been other threads of people getting flakey crank sensors.
In another current thread the OP had no-start problems with 4 new crank sensors until he bought one from the dealer. From supplied pictures it was evident that Amazon was selling FAKE GM/ACDelco parts because the logo on the package was wrong. Not saying your crank sensor is bad, but there have been other threads of people getting flakey crank sensors.
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Which cylinder(s)are misfiring? I know it's kicking a P0300, but you should be able to see it in the active misfire counter.
To answer your question, you need to find a shop that has a really good diag tech and an ocilliscope.
You would have saved thousands of dolllars.
To answer your question, you need to find a shop that has a really good diag tech and an ocilliscope.
You would have saved thousands of dolllars.
Thread Starter
Teching In
Joined: Oct 2023
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Which cylinder(s)are misfiring? I know it's kicking a P0300, but you should be able to see it in the active misfire counter.
To answer your question, you need to find a shop that has a really good diag tech and an ocilliscope.
You would have saved thousands of dolllars.
To answer your question, you need to find a shop that has a really good diag tech and an ocilliscope.
You would have saved thousands of dolllars.
Thats not even hardly testing injectors. That doest tell you if one is leaking, if one is not spraying correctly, or if the are flowing correctly. They have to be removed and tested in a high quality machine.
Did you do a CKP relearn after changing crank sensor?
Verify the 5,7 snd 6,8 injector connectors are on the correct cylinders seen these crossed too before
On a side note have you had the pcm and tcm if it's an auto updated with the latest flash programming. shop or dealer has to do it though it's not something updateable via HPT or or other tuning platforms. 08-09 had tons of updates to calibrations the first few years. I also remember more than one truck which a flash update corrected a PO300 even though it wasn't listed as an update in the calibrations and it's the exact same pcm used across multiple platforms.
Next question auto or stick I have seen a few clutches/flywheels cause a p0300 too
And seen a few torque tube couplings cause same thing
PO300 sucks to resolve best of luck
If all of the above check out throw a big ol cam in her and turn that **** off and let r eat.
Verify the 5,7 snd 6,8 injector connectors are on the correct cylinders seen these crossed too before
On a side note have you had the pcm and tcm if it's an auto updated with the latest flash programming. shop or dealer has to do it though it's not something updateable via HPT or or other tuning platforms. 08-09 had tons of updates to calibrations the first few years. I also remember more than one truck which a flash update corrected a PO300 even though it wasn't listed as an update in the calibrations and it's the exact same pcm used across multiple platforms.
Next question auto or stick I have seen a few clutches/flywheels cause a p0300 too
And seen a few torque tube couplings cause same thing
PO300 sucks to resolve best of luck
If all of the above check out throw a big ol cam in her and turn that **** off and let r eat.
Last edited by 01WS6/tamu; Oct 28, 2023 at 08:21 PM.
Thread Starter
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