riflerack31

Hi i have a full size 2008 silverado with the 5.3l engine. I have had this problem for a little while. While I idle the truck for like 2 or 3 mins the message on the dash says stabilitrack off, service stabilitrack, stuff like that. Then CEL comes on. Sometimes the CEL flashes. Runs rough for a while then when i get goin at like say 40 or 50 mph for a ways the service stabilitrack message goes away but the CEl is still on, and seems to run fine. I have a superchip and the diagnostic comes with up with a code P0308 misfire cylander 8. IV changed the pluggs and wires and swapped the coils. What do you guys think?

tech2

stabilitrac will be disabled due to the misfire. do a compression check.

thzpcs

Sounds like an actual issue with the cylinder, or the head. If you've checked everything else, then that's where I'd go.

riflerack31

Ill do that. Do u think it might be a bad injector?

tech2

its possible, but gm fuel injectors are pretty good for that generation.

jgray152

Could be intake manifold gasket. Usually manifold gasket symptom is rough idle/low rpm and runs good higher up and under load. Depending on how bad it is.

Do a compression check first on cyl 6 and 8 to see any difference. Pull fuel pump and ign relays or fuses.

You can bring it to a shop and have them run a fuel injector balance test. I don't believe this is 100% effective to determine if the injector is bad but its a good flow test.