P0306?

[Redstar2112]

Hi all; advice needed. I've owned my 04 T4R for about a month now, bought from the original owner with 230k miles. A few days after I got it, the CEL & VSA lights came on when starting up one cold morning. I did some cursory searching, decided to try tightening the gas cap & resetting the code. It went off & stayed off for about 1500 miles.

Yesterday morning, it started a little rough (but smoothed out within seconds) and the lights came on again. Had my neighbor pull the codes with a reader & got the P0306 code back, misfire on cyl #6. While researching, I see that this code could mean roughly 1000 things, the worst being a blown head gasket. Well, the day after I bought it, I took it to my regular mechanic & had him do a pretty thorough inspection, specifically asking him to check major engine components. He said it looked great & like it had been impeccably maintained.

I know you guys can't narrow it down for me, but my main question is this - I have a long way to drive for work tomorrow (about 400mi round-trip). Aside from the lights being on, the truck seems to be running perfectly all day yesterday & today (drove about 120 miles since they came on). Should I try and make the drive, or is this something where I need to wait and have my mechanic try and diagnose the problem first? Is it foolish to try and do this, or am I better safe than sorry and just need to rent a car? (I can't put the trip off)

Thanks for any advice!

EDIT: I do not smell any gas in the coolant cap/reservoir, I don't hear any sloshing sounds, and the truck seems to run just like normal. Once in a long while, it will shimmy a tiny bit right on startup, but only for 5 seconds or less, and the lights have only come on the 2 times I've listed.

 

[waypoint]

It's your decision whether to take the risk and road trip it with an active misfire code. I wouldn't.

No point typing up diagnostic procedures to narrow down the cause of the misfire, as your mechanic will be doing the work.

 

[rumfoord]

Hate to say it but sounds like the dreaded head gasket issue. Had the same code and "shimmy" on start up. Drove it a it after that just to get diagnosed and continued to get worse, ended up seeing the white smoke out the exhaust and noticed coolant level decreasing.

Check you coolant level and keep an eye on it, even maybe mark where it is cold and the next day when cold check again (remember levels fluctuate when cold and hot).

Can also try swapping the ignition coils to see if still get misfire on cylinder 6, if moves to the other cylinder after resetting code then could be ignition coil.

Mechanic can do other tests like pressure etc to confirm if is or isnt head gasket.

I'd avoid doing any major driving though, last thing you want is coolant in with the oil and potentially causing more damage.

Best of luck.

 

[Redstar2112]

Thanks for the advice all. Ended up renting a car & took the 4Runner to my mechanic. He checked the coils (all good), changed the plugs & that seems to have taken care of the the problem.