Impala Forums banner

1 - 3 of 3 Posts

·
Registered
Joined
·
1 Posts
Discussion Starter #1
2008 Chevrolet Impala LS 3.5 V6 flex fuel
Check engine code: P0304

Please help my horror story. I purchased my Impala 2 years ago, love my car. However, there has been a shadow in the form of a check engine light that I have always had. I purchased the car, the check engine light came on: P0304, multiple maintenance trips and multiple fixes over these two years.

- changed spark plugs
- Replaced catalytic converter
- Switched to premium octane gas
- Purchased new gas cap
- Tried two different fuel injectors

No matter the attempt for resolution, It comes back with P0304. The car otherwise runs fine, but I'm tired of having the check engine light on, especially since it disables the automatic start feature on my key remote. Any ideas on where to go next?
 

·
Registered
Joined
·
598 Posts
P0304 is a cylinder 4 misfire I believe.

I see you've tried addressing it already, and you've changed the sparkplugs. Did the wires and coil pack get changed as well? Did you check for spark on plug 4?

Maybe swap plugs and wires between cylinders and see if the misfire goes to another cylinder as well. If not, I'd focus on the cylinder itself. Possible reasons could include fuel injector issues and exhaust valve issues.

Hope this helps!

Edit: I forgot you already checked injectors, so ignore that part.
 

·
Registered
Joined
·
1,074 Posts
Coil pack came to mind here as well. Not sure if that model uses a a separate coil pack and ignition module or if it is an integrated unit. Would use a plug wire tester on cylinder 4 and see if you are getting any spark there.
 
1 - 3 of 3 Posts
Top