P 0306 cylinder 6 misfire

Payson

Active member
Aug 14, 2017
35
2
SOUTHERN CALIFORNIA
I had a code telling me I had a bad upstream bank 1 o2 sensor, and running lean. Drove it a little until I was able to change the o2 and the P 0306 code showed up. The misfire is noticeable for sure. Pulled the plug, looked a little oily, not terribly, replaced it. No change, got an inline spark tester and I definitely have spark at the plug. all codes cleared but the misfire at this point. I am assuming, and maybe I shouldn't, that the spark at the inline tester tells me the wire and the coil are good. The next issue I can think of would be the injector. Would a seafoam treatment be a good idea for a possibly fouled injector? I ran seafoam in the tank (half a bottle to 1/2 a tank of gas) and then filled the tank up at about 1/4 with no seafoam. This has occurred about 1/2 way through that second tank.

Any ideas? do a a seafoam? Am I wrong on assuming the coil is good? Should I look at the injectors? anything else?

Help would be great.....
 

Payson

Active member
Aug 14, 2017
35
2
SOUTHERN CALIFORNIA
Thanks, I've replaced plug, checked spark at the wire (using an inline tester, it has spark), did a vacuum test and vacuum is good and stable. No white smoke, but smell of unburnt fuel. Also sound is distinct resonating from the throttle body it seems. I am assuming a bad injector at this point, but will do a compression test to make sure something more serious is not present. funny thing, that is the only code I'm getting
Thanks for the response!
 

JohnB

Well-known member
Oct 18, 2007
2,292
12
Oregon
If you are getting pops up into the intake my guess is you have a mechanical issue.
Stuck valve, bad cam lobe but for sure a compression test is the first step.
 

Payson

Active member
Aug 14, 2017
35
2
SOUTHERN CALIFORNIA
turns out it was a blown gasket on the intake side of #6. Looking at the gasket and the condition of the bolt between 4 & 6, it looks like the bolt was not torqued properly on the last install. When I went back in with the the bolt in that hole, that bolt stripped the block thread. Now doing a time sert to continue.

Thanks for the reply!