My Tundra started running rough today, and the "check engine" light came on.
I plugged in my scanner and it came back with P0307 which is a #7 cylinder
misfire detected. I had a similar situation about 9 mos ago and it turned
out to be a bad coil pack on cylinder 5. I replaced the coil pack and the
problem went away that time.
This time - not so much. I pulled the coil pack from cylinder 7 and replaced
it with one off the wife's Sequoia. No improvement and same code. I pulled
the spark plug and it was dark brown and looked like it was just along for the
ride. I pulled a plug out of the Sequoia and installed it along with the coil
pack and still no improvement and same code. I pulled all of the plugs and
found all of them very dark brown with gaps about .045 or more. I installed
these plugs 25000 miles ago and each one was gapped to .031. The plugs
are NGK BKR7EVX-11s. I know the "tune" on the supercharger ECU is very
rich which explains the plug color, but the big gap has me confused. I
re-gapped all the plugs back to .031 and installed them with all the coil
packs from the Sequoia, no improvement and same code. I plan to
replace the NGKs with E3-64s since they appear to have such a short
I think I have covered the electrical end of the diagnostic, so I'm thinking
possible bad fuel injector? Maybe even a CAT related problem. This is a
Three catter Cali truck.
Truck has 55000 miles and gets a bottle of injector cleaner every third
Any help/suggestions would be greatly appreciated.