Misfire P0300 HELP

You may have some issues with the valve train, vacuum leaks need to be checked for, but why would a push rod be bent in the first place would be the question. P0300 CHEVROLET - Cylinder Misfire Detected Random Cylinders- Possible causes - Faulty spark plug (s) - Faulty ignition coil (s) - Clogged or faulty fuel injector (s) - Intake air leak - Fuel injectors harness is open or shorted - Fuel Injectors circuit poor electrical connection - Ignition coils harness is open or shorted - Ignition coils circuit poor electrical connection - Insufficient cylinders compression - Incorrect fuel pressure- The P0300 code means that a cylinder(s) is misfiring or is randomly misfiring. Start by checking for intake leaks, intake gaskets are common caused of multi-cylinder misfiring. If no leak are found the next step is to replace the spark plugs. If the problem persist more tests needs to be done to diagnose problem....

I changed sparkpug and wires car ran ok for a few weeks but now po 300 comes up. On my 2004 yukon

Had random misfire code p300 on my 2007 Yukon Denali, ended up being no ground on passenger side and needed new throttle body....gmc said I just needed new engine ($8100.00)

Try crankshaft relearn on a scan tool

Definitely not a spark plug voltage of the coil grounded anything like that the one guy had a bent pushrod and that is caused by timing I would be checking cam sensors crank sensors and I believe there is something with the timing chain or gears that also has a sensor Those sensors go out or are Miss calibrated then it will throw everything out of whack and then the spark will not ignite when the computer says it is supposed to and that will give you a misfire

Also if your GM vehicle is not flex fuel, you may have a problem using different octane rated fuels or if you use a octane booster injection cleaner or any other kind of additive that you put in your fuel. That will mess with the computer, most of the time the computer will sense the fuel or the rate that the fuel Burns and then it will program itself to run the best that I can with the fuel or additive that you were using so that you do not end up with misfires timing problems or loss of power. Also it depends on where you get your gas if you just stop at any random gas station can you are going to get different fuels but if you keep consistent to a certain brand then you will less likely have a problem, I speak from experience because I had a older vehicle and the owner that sold it to me had ran 91 in it for over 10 years, then me just needing it for a work truck and a simple commuter used 85 because everyone knows you will get better mileage with 85 than 91. And that is where I screwed up, after about 3 fill ups I started to notice a change in the performance and it would occasionally start overheating and then one time I got of plume of smoke out of the exhaust well I started to check the plugs and the alternator and the fusible links and the voltage regulators and the ignition and fuses and the battery and fuel filters and ended up getting screwed over for a complete new CPU, I mean they said they replaced it but I marked it with a black Magic Marker and then took a picture of it and when I went to go pick it up I checked before I left a lot and it was the same one. So I actually had to end up selling it for less than 1/2 of what I bought it for because I could not figure the problem out and then the guy that I had sold it to about 4 months later told me it just started working, and I asked him what he did and he said I didn't do anything I drove it with its problems and then it fixed itself.. and then with further discussion I found out that he started using 91 along with a octane booster. Also if you take your car into a Tire or Lube place for an oil change or inspection and you do not pass. DO NOT let them fix the problem they are Lube technicians they are not mechanics and most of the time they will Outsource a mechanic that they use which, which 98% of the time is not a mechanic either and that is how I got charged $900 for a computer that never got installed and then all the other diagnostic and a changing of the other parts and everything trying to eliminate every possibility of the problem that was about another $600 good luck to you and no matter how nice or how many things they say they're going to improve on your car, remember this they just like you have a job in order to make that money they need to sell they need to up-sale you on something.

I was getting the p0300 and traction control needs serviced prior to my tune up. It was also running rough and smelled bad. The crankshaft relearn was my solution after I did a complete tune-up. It ran horribly before and after I changed the plugs and wires, I was sure there was another issue but a mechanic friend who had a scan tool with crankshaft relearn on it said that the truck was so far out of tune and that the computer was retaining corrupt settings from the plugs being so fouled that a relearn was necessary to bring the tune parameters back into tolerance. It ran perfectly after the crankshaft relearn.

Most likely its your distributor cap or crankshaft sensor.check your cap its most likely it

It’s your catalytic converter!