P0303 OBDII code on 2007 Silverado Vortec 6.0

[Shonzta]

Hey Whats going on Chevy enthusiasts. Ive seem to run into a wall with my P0303 problem, wondering if you all can chime in. Here is the issue. I have a 2007 silverado 2500hd vortec 6.0 engine. I got the check engine light on. OBD read P0303 (cylnder3) mis-fire. Ok so first thing a I did was change the cylinder 3 spark plug (still mis-fires) then I checked for spark on the coil and yes it has spark (still mis-fires I checked the spark plug wires and they seem ok. I also changed the Fuel injector (still mis-fires).

 

What else do you think I should check? I hope I dont have low compression my engine only has 91k miles....but shit happens.

 

Chime in let me know what you think...

 

Much Appreciated...

 

Oh by the way Im new here

[txab]

Swap coil pack and wire with another cylinder and see if miss follows. Check for a vacuum leak as well

Edited January 28, 2017 by txab

[davester]

yeah, swap the coil to another cylinder, and if it still misfires on the same cylinder, you could try swapping the fuel injector to another cylinder and see if it still misfires.

[Shonzta]

yeah I swamped the coils and spark plug wires still misfires. I havent check for Vacuum leakes so going to do that. Thanks for the advice.

[Terry Stickel]

What did you figure out with this issue? I am having the same issue. So just doing some research before I start parts slamming.

[Colossus]

he never returned to report on solving the issue. 

[RK2125]

I have a 2000 Sierra 2500 with a 6.0 Vortec engine. I am also getting a P0303 code.  Which one is cylinder #3?

Edited March 26, 2020 by RK2125
more info

[RK2125]

Thanks anyway.  I've figured it out.  Drivers side 2nd back.