P0300 Multiple misfire code - check individual cylinders?
P0300 Multiple misfire code - check individual cylinders? My 98 z28 is running rough and throwing a P0300 random/multiple misfire code. I found 1 broken valve spring and replaced it. It still runs rough and throwing the same code (after clearing the previous code).
My question: is there a way to find exactly which cylinders are misfiring? Because I believe the way it works is if one cylinder is misfiring, a code will be thrown for that specific cylinder. If two or more cylinders are misfiring, the random/multiple misfire code is thrown.
It would make diagnosing this problem much easier if I knew exactly which cylinder(s) to look at.
Thanks in advance for any help.
My question: is there a way to find exactly which cylinders are misfiring? Because I believe the way it works is if one cylinder is misfiring, a code will be thrown for that specific cylinder. If two or more cylinders are misfiring, the random/multiple misfire code is thrown.
It would make diagnosing this problem much easier if I knew exactly which cylinder(s) to look at.
Thanks in advance for any help.
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Joined: Aug 2007
Posts: 28
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From: STL, MO
^^^ Agreed. Run a compression check. My 02 Z28 was running a little rough and throwing code. Held 190 psi on all cylinders except 1. Good 'ol #7 only had 90 psi. Pulled the piston to find a broken ring land.
In my experience p0300 is usually caused by unmetered air entering the engine. I.e. bad throttle body gasket, leaky intake gasket or cracked intake. Secondly I check for weak fuel pressure. Next I ohm out cam/crank Position sensors. 4th step is leakdown/compression test. Almost always specific cylinder misfires will throw a relative code to that cylinder. My .02
Well I did a compression check. Cylinder #2 was low. Air was coming out of the exhaust. That's what I figured it would be since the valve spring broke on the #2 exhaust valve. Looks like the heads are coming off... again. Second time this month. Hopefully the valve didn't cause any damage (I was lucky last time).
I'm not sure why it wouldn't be just throwing a #2 misfire code though. I'll probably end up finding something wrong with another cylinder.
I'm not sure why it wouldn't be just throwing a #2 misfire code though. I'll probably end up finding something wrong with another cylinder.
