P0300 Chevrolet -

Question

I have code p0300 and code p0496 2004 suburban 8.1L

Answer 1

P0300 Random misfire

P0496 EVAP emission high purge flow fault

Having a random misfire do come from false air such as vacuum leaks,low fuel pressure or excessive back pressure,But with P0496 this can cause random misfire check and inspect the purge line for proper hose connection. The open purge flow may be the cause of random misfire

Comments

I have an 03 chevy venture and P0300 and P0449 are coming up it is running rough, really bad rough, spitting and sputtering so bad that you cannot drive it any more and it will stall out. We changed the canister vent valve solenoid thats on top of the gas tank, but then i found out about the purge valve thats on top of the motor. But i get different answers from every person I talk to, some say a bad purge valve/vent valve will cause random misfire and some say  it will not, and i cant get a clear answer on line either. The only symptoms it says is the check engine light will be one.