P0300 code, can't seem to get to the bottom of it.
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TECH Enthusiast
Joined: Jul 2007
Posts: 622
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From: Calgary Alberta
P0300 code, can't seem to get to the bottom of it. My car has been throwing the P0300 code since I put in the new cam. It was originally running like crap, shaking a lot. It's an EPS Cam 226/234 .598 .601 113.
I replaced the plug wires, noticed a couple were loose. That helped a lot. Took a couple days for the light to come back on.
Then I went looking for Vacuum leaks, I found one tiny little loose vacuum line behind the LS6 intake, so I plugged that in. That really helped, idles much better now. But it still threw a code after about 3 days. It shows P0300 two times ( I'm assuming that means both banks ). And the "ev" light is flashing.
I'm thinking it's another vacuum leak and will be doing some more searching today.. how many of those little vacuum lines are behind the intake?
Also I blocked off the AIR and EGR, could it be those? The car runs great now, and there really are no visible issues or signs of power loss... but I don't like the idea of a missfire.
Ideas?
I replaced the plug wires, noticed a couple were loose. That helped a lot. Took a couple days for the light to come back on.
Then I went looking for Vacuum leaks, I found one tiny little loose vacuum line behind the LS6 intake, so I plugged that in. That really helped, idles much better now. But it still threw a code after about 3 days. It shows P0300 two times ( I'm assuming that means both banks ). And the "ev" light is flashing.
I'm thinking it's another vacuum leak and will be doing some more searching today.. how many of those little vacuum lines are behind the intake?
Also I blocked off the AIR and EGR, could it be those? The car runs great now, and there really are no visible issues or signs of power loss... but I don't like the idea of a missfire.
Ideas?
Was the intake manifold off? Try spraying brake clean along each bank on the intake/head gasket line. If it changes the idle then you found a leak. Generally if the intake is leaking you will get a P0171/0174 Lean Fuel trim to accompany this. Just thought worth checking it over. This same tip will work as you spray over vacuum lines to check for leaks.
Check under the rubber elbow that connects between the passenger side of the throttle body and the PCV line. You'll have to feel it with your finger or use a mirror and look on the underside of this elbow. If you find a hole, that's your problem.
Thread Starter
TECH Enthusiast
Joined: Jul 2007
Posts: 622
Likes: 2
From: Calgary Alberta
I should also note that the code only pops up if I let the car idle for a bit. I've driven almost 300 miles and it didn't go off. But if I let the car idle for half an hour it pops the code.
Nothing is wrong with your car
it is completely Normal with an aftermarket cam
p0300 is the code for a random cylinder misfire...
it happens when you put a cam in that does not have a stable idle...
meaning just about every cam on the market bigger than a 224/224 will cause this...
it happens when the pcm sees an unstable rpm signal that varies by more rpm than expected...
you need to get a better tune in the car, and most likely will still need to just turn the code off.
Leave the SES/MIL enabled and set the code to "No error Reported"(If using HP tuners)
it is completely Normal with an aftermarket cam
p0300 is the code for a random cylinder misfire...
it happens when you put a cam in that does not have a stable idle...
meaning just about every cam on the market bigger than a 224/224 will cause this...
it happens when the pcm sees an unstable rpm signal that varies by more rpm than expected...
you need to get a better tune in the car, and most likely will still need to just turn the code off.
Leave the SES/MIL enabled and set the code to "No error Reported"(If using HP tuners)
