PO300 code

[chevyv8350]

I have a 2002 Silverado 1500 5.3 and I get a check engine light from time to time. I get the code and it reads P0300. The check engine light stays on for up to a week then goes off. Mysteriously it will come back on and I'll read the code and it's P0300 again. I've changed the plugs and wires, it helped for a while. What else could it be?

 

[CamGTP]

Could be a coil pack, vacuum leak, exhaust leak or even a fuel issue like injectors or weak fuel pressure.

 

You must narrow the misfires down before just throwing money at it. A live data scanner needs to be used so you can monitor each cylinder and watch misfires in real time. Figure out what cylinders they are and trouble shoot from there.

 

Also look at live data fuel trims and test fuel pressure. If fuel trims are very positive you have a vacuum leak or exhaust leak pre-o2 sensor. And fuel pressure should be above 50psi at idle for sure.

[chevyv8350]

Thanks CamGTP. I'll look into these areas.