2000 5.3l Cel, Code P0304

[Grip72]

driving around from work today and BAM, CEL light flashes and then goes on steady. did some research while at work and then drove to the closest place with a free code reader. Showed my code P0304, misfire in cylinder 4. so i googled it and came up with:

 

A code P0304 may mean that one or more of the following has happened:

 

Faulty spark plug or wire

Faulty coil (pack)

Faulty oxygen sensor(s)

Faulty fuel injector

Burned exhaust valve

Faulty catalytic converter(s)

Running out of fuel

Poor compression

Defective computer

So i bought new spark plugs and wires and threw them in. The old ones looked pretty grubby and my truck has 294,000kms on it.

 

Fired it up and the light still stays on steady. Went for a drive, the light will flash if I'm driving around or stay on steady. At red lights/stop signs the CEL mainly stays illuminated. I really don't want to drive my truck anymore and wreck it furthermore. I just don't know what to do next! I need my truck for work everyday, my last day of work is on the 19th and then the truck will be stored on the 31st for a year, BUT I still need to drive it ALOT before then...ugh

 

any suggestions as to my next step? I do get a nasty smell but it's not rotten eggs. Think my cats need replaced? O2 sensors? Should I just suck it up and take it to a mechanic?

[Nytemare]

rotten egg smell is cats...90% of the time, but it could be excess fuel getting catalyzed by the cats due to the misfire on cylinder 4.

 

First thing you do is swap the #4 coil pack with the one next to it...#6....and see if the code becomes P0306

a flashing CEL means the misfire is active.

 

I am going to go out on a limb here and say that its almost certainly a coil pack causing this issue. It fits all your symptoms.

[Grip72]

WOOT WOOT

 

it was the ignition coil!

replaced it and it's good to go!