P0308 Misfire Code while road tripping

[Rocket Man]

I'm actually more worried about pulling the cylindrical heat shield, boot and wire. And doing so without messing it up.

Just pull by the boot, don’t pull on the wire. They do make plug wire pliers that grab the boot, might have some at your local auto parts. The heat shield just pulls up out of the way fairly easy I believe (going by memory here, I have headers so no longer use those). Worst case is you buy a new set of wires if it becomes separated.

 

[Doubeleive]

these bent nose pliers are great for reaching in and grabbing the plug boot
https://www.harborfreight.com/hand-tools/pliers/20-offset-45-angle-long-reach-pliers-2-pc-64090.html

 

[YukonXLMan]

I got a po305 error code while driving up 95 to New Jersey today. I cleared the code and then drove another hundred miles with no code. Thinking that it might have been injector getting plugged with something from the fuel.
I don't plan on messing with it unless it happens again. Please let me know if you think that would be a mistake.

 

[OR VietVet]

I got a po305 error code while driving up 95 to New Jersey today. I cleared the code and then drove another hundred miles with no code. Thinking that it might have been injector getting plugged with something from the fuel.
I don't plan on messing with it unless it happens again. Please let me know if you think that would be a mistake.

I don't think it is a mistake at all. I have seen what I call "soft" codes pop up for what seems like no rhyme or reason. It typically is a momentary glitch that may never happen again. I used to note them down and then if it came back way later I had a history.

 

[Rocket Man]

What Ron said.^^^^. Just keep an eye out for it to pop up again. I always take a picture with my phone, it provides a date to go with the code. I was having evap codes pop up and they were so random that sometimes they wouldn’t show up again for months. I would replace one part, like the purge valve, and clear the code. Then I would think it was solved until another evap code would pop up maybe a month or 3 later. I could scroll back through my pictures and see what code it was and how long it had been.

 

[YukonXLMan]

Thanks for the feedback. As luck would have it, I did just that and will keep the pic for records should need arise. Drove another 300 miles today with zero issue. Perhaps it was just bizarre timing, but the day it occurred was the only day I filled my tank with 8 gallons of E85 and rest 91. Today just filled up with 91 Octane prior to the 300 mile run.

 

[dro45]

I had the same code. I decided it could also be a dirty injector. I ran two tanks of gas through with Techron added to each. The code went away and has not returned. Worked for me, that's all I know.

 

[Burby]

Ran seafoam through the TB and drove her hard as recommended for 10 minutes. CEL came on blinking after 300 miles on return trip. 41k miles. Checked the code and it was a missfires on more than cyl 8 now. Leaving to move and need to trailer with the suburban so took it to the dealer to let them dig into it. DID NOT MENTION SEAFOAM TO DEALER.

They found nothing in their diagnostics and want to do a $485 fuel rail and TB flush (much higher concentration than seafoam and requires an oil change). I said it sounds like a powertrain issue with that approach and they said not yet. The counts they showed were:

cyl 5 364 mf
cyl 7 590 mf
cyl 8 1040 mf
cyl 3 22 mf
cyl 6 15 mf

I am unsure of how long the tech ran the car and in what rpm to get these numbers.

Freaking out a bit because I gotta leave the state and need to take this car - I think I might wait until I reach my destination to do such a flush.

Thoughts?

 

[HiHoeSilver]

I would Kreen that puppy just for fun.

 

[Cantrepeat]

The questions remains, were you with your two favorite allies?