CEL, 4LO, Trac off. Code P0308 (1 Viewer)

Joined
Jun 20, 2019
Messages
75
Location
Houston, TX
Hey fellas!

Getting a misfire on cylinder 8. CEL, 4LO and Trac off on the cluster. Code is P0308 which is misfire on cylinder 8. I’m thinking coil pack or spark plug? I know this was an a common issue on the old 4.7 but haven’t seen anything on it on the 5.7. Thoughts?

-Pat
 

Sandroad

SILVER Star
Joined
Jan 31, 2009
Messages
3,133
Location
Michigan
 
 
#8 is passenger side rear. How many miles On the plugs? Do you have the tools to pull the plug and take a look?
 
Joined
Jun 20, 2019
Messages
75
Location
Houston, TX
#8 is passenger side rear. How many miles On the plugs? Do you have the tools to pull the plug and take a look?
I don’t have a socket long enough sadly, but that will be my next guess. I went ahead and swapped the coil pack between 6 & 8. Definitely not the coil pack. 51k on a 2014.
 
Joined
Jun 20, 2019
Messages
75
Location
Houston, TX
I also had a flowmaster muffler on there for a bit, just had the stock muffler put back on this week. Noticed a lower idle speed since then. Chances that the muffler swap messed with the O2 sensor, thus causing a misfire?
 

kcjaz

SILVER Star
Joined
Feb 7, 2016
Messages
401
Location
Olathe, KS
I had this exact thing happen. It was the spark plug. Spark plug would not come out at first and the dealer initially said they might have to remove the head. Luckily it they were able to get it out.
 
Joined
Jun 20, 2019
Messages
75
Location
Houston, TX
I had this exact thing happen. It was the spark plug. Spark plug would not come out at first and the dealer initially said they might have to remove the head. Luckily it they were able to get it out.
ok cool. Looks like an Autozone trip is in my future.
 
Joined
Jun 20, 2019
Messages
75
Location
Houston, TX
Ok. So the issue is intermittent, usually happens after I start up the car for the second time in the day. I clear the code and it's gone for the rest of the drive. I ran my tank basically dry and put some new gas in (my thought being maybe bad gas). I start up and it runs smooth. But then it came back last night... So my thoughts are maybe O2 sensors, something in the evap system, a wiring issue on cylinder 8 or maybe I just got some s*** gas. I know a common issue is the soy based wiring insulation underneath the intake manifold attracts rodents so maybe it's that?

Again, thoughts anyone?
 

Users Who Are Viewing This Thread (Users: 0, Guests: 1)

Top Bottom