P0306!!

Hi all,
I apologize in advance for the lengthy post, i wanted to be as thorough as possible as i have had so many different diagnostic darts thrown my way in the last few months.
My 05 v6 tundra has 175 thousand miles on it, it has been maintained well over all and has always been a steady truck. A few months back it developed a slight shake/strong vibration at start up, very intermittently, but always on cold starts. Once it warmed up the truck idled fine and ran normal.
Finally, after about a month of these random funky starts, I started it, put it in gear, as I did that it sputtered, I gave it a little more throttle it worked through the choke but check engine light came on. I was yet to see that light and was perturbed, I immediately went and bought code reader anxious to pinpoint a problem. p0304, I researched that and decided to give it new dgk plugs and even bought 6set of coil packs online. All was good, no obvious sign of foul plugs (cyl 4 plug looked fine as well) so i proceeded to replace plugs and coil packs, started and ran great..for a few weeks.
Until one morning before work i went to warm it up and when i came back out, it threw a code again! This time I got p0306. I found that a lot more issues fall under this code? I have a friend with an auto repair shop and when i ran it by him he had me do MAF and clean the throttle body, surprising myself, I did that with no issues. Again, code reset and truck ran great...for a few weeks..
So that is where I am at as of now as far as repairs, now the truck will go through week running and starting just fine, then randomly throw the p0306 code one morning. The truck will get bad mileage whenever the light is on, this will go on for a day or two then i start it, no light, truck runs fine, normal mileage..
There is a list of scary things I have heard (heads,head gaskets,cpu) and just wanted feedback from any one who has seen this troubling issue .. THANK YOU

 

Hi Eddie. From the symptoms you described it sounds like you have an injector going bad, or possibly an O2 sensor going bad but it sounds more like an injector. Try running a bottle of fuel system cleaner through it to see if it clears up, it's possible that you have a dirty injector.

 

Hi there-
Thank you, I appreciate the response. The next thing I was going to do was replace fuel injectors and o2 sensors. After cleaning throttle body and MAF, the code came back, then I ran a bottle of Lucas oil fuel injector cleaner with a tank of 91 fuel. It ran better for a few days but then threw the code on a cold start. I believe I can do injectors and o2 sensors myself, but after that I would not have a clue what to chase down the line. I'm thinking about biting the bullet, taking it to the dealership to try to pinpoint p0306 diagnostic. Latest research i read was a guy with similar problem : at start up, truck would shake and throw code. 6th cylinder is farthest back from cooling system and is area of the gasket that tends to go first. If that's the case coolant is getting into that cylinder upon startup and the truck is trying to burn a non combustible, thus throwing the misfire code. When check engine light is on it runs worse as it is in some default "limp" mode?.. With the normal maintenance of the vehicle and it has never over heated, I mean I've never seen temp gauge past halfway , I don't know how the head gasket would be going, and if it was- wouldn't it just run crappy all of the time ? Urrgg!!
Eddie

 

If your head gasket is 'on its way out', you should notice some white smoke at start up. Depending on how quickly it's going you would also notice a loss of coolant and possibly a slight milkiness in the oil. Might be worth a few bucks to take it in and have a Toyota tech take a look and pinpoint the problem.

 

Head gasket. The early 1GR-FE (4.0L V6) had a weak point in the head gasket that weeps coolant into #6 cyl, and causing P0306 missfire codes on startup.

Pull #6 plug after it sits overnight, and have someone crank it while you hold a white paper towel over the spark plug hole. It will get damp and pink from coolant.

https://www.tacomaworld.com/threads/1gr-fe-head-gasket-failing-options.338360/

By no means the first I've heard of, not uncommon, at least not uncommon enough in the Tacoma world.

 

My 4 Runner had similar issues and I cleaned the MAF. Problem came back. Tried a lot of the stuff you did. Turns out I didn't do a good enough job cleaning the MAF.

 

The little sensor needs to be cleaned really well or even replaced.

 

Could be a bad #6 coil as well seen plenty of bad newer aftermarket coils

 

Scary stuff - thanks for the information everyone. Unfortunately worst case scenario is now seemingly reality. I have lost plenty of coolant over the week- and on my way home from work today, truck was missing/sputtering at 60mph, when I gave it gas, didn't want to go. Check engine light began to flash, have yet to see that. I'm afraid its more likely gasket than anything electrical which I know now from landphils heartbreaking link is not cheap. 175 k odometer- 1500$ roughly to get another 175k..?

 

Bummer Eddie, that sucks! I hope everything works out for the best.

 

Yeah, sorry about that bad news Eddie.

 

Appreciate that guys- I looked into pricing with my buddy that owns auto repair shop near me. His friendly yet professional price was 2,200$ for both sides of the head with the water pump. He said his brother who is a mechanic can piece work it out for a little less and i would still get wholesale on parts, just no real warranty I guess.
I have to say even with the low low blue book value on my truck (4300$) vs the 2k I would have to put in, I would still get head gaskets done try to get to 300k on a good truck. .. Or try and use gasket sealer and see how long that gets me, any thoughts on that type product? I'm very tied up over all the contemplation but I have 2k and that's it, like to know what may be best logically
1.. Put gasket sealer, hope for the best .
2.. Pay premium get it done
3.. Use 2,000$ and ballkick trade in to get into monthly payment?!?

 

If it were me (and it was not so very long ago) I would stay away from the "mechanic in a bottle". Sealer stuff usually causes more problems than it solves. I say find another, newer Tundra you like, go for the trade and hand the problems off to somebody at an auto auction ('cause at 175k and 12 years old you know that's where it's goin'). I know getting into a payment sucks and stuff like this always comes at the most inopportune time but somewhere out there is a rescue Tundra hoping that you'll give it a good home.

 

I had the same issue on my Tundra. I noticed my check engine light would hit when I was driving on a good acceleration or when I would cold start it. It would also go into limp mode as well. I had to disconnect my battery for at least 3-5 minutes before I could dive my truck without hesitation or the check engine light going off. I did some research and found out that the secondary air pump system, could be the issue. Before that I tried new spark plugs, coils, new vacuum hoses (some did need replacing for sure), cleaning the air intake, ect. If the engine would run fine after a reset, the head gasket wouldn’t be the issue, since it seemed a computer reset got it up and running again. I saw that the exhaust goes into the valves that allow it to go through hoses, into two motors that spin the air into the intake scoop in the passenger fender well area, near the front. The motors have a rubber housing. I poked a hole at the bottom to see if water would come out and none did. So since I wasn’t cording for it, I wasn’t worried about that part above that by the passenger side of my 4.0 engine are the valves connected to the exhaust pipes and have two vacuum hoses on them as well. I took them apart and found that one of the valves had a stuck gasket in it and a broken piece of metal that I took out. I also cleaned it out as well. I also replaced the vacuum hoses on the valves. I decided to cut an opening on my air intake tube where it sits behind the washer bottle. I figured if that’s the case, better air flow will help as long as I cut the size where it’s not going to suck any air heated by the engine. There are other videos I watched that helped me by searching limp mode with your year engine size and model. There is even bypass kits you can get for it. This is Toyotas advanced pain in the ass EGR system. Since then. I haven’t had an issue, yet. My truck seems to drive way better. I also replaced my gas cap since it was old to hold better pressure.

https://youtu.be/lsV1HCcuEIo?si=w0QM4lPGQPAAdWye

 

In a very similar situation right now with my 3.4L. Seems like the 3.4 and 4.0 have head gasket issues.