2013 4.0 cyl 6 misfire

I bought my Tacoma a few weeks ago and love it, but noticed it running kinda rough especially during a cold start. Also, it will "hiccup" while sitting at a light or stop sign. Today it finally gave me a cel and it was P0306, so I switched the plug and coil with cyl 5 to see if the problem followed the parts. I haven't gotten another cel, I will check it in the morning.

My main question:
While researching, I have seen a lot of 4.0 cyl6 misfires that are caused by a bad head gasket on the earlier years (2005-2006) and read that in 2007 they updated it? Is this accurate? Is this still a problem in the 2013 4.0s? Thank you.

 

So far as I know the later 4.0s (07 and up) don't have HG issues. That's not to say there won't be a fluke failure or two or two out there. What did the cylinder 6 plug look like? How many miles? Original plugs? Original plugs are Ngk on the passenger side and Denso (I think) on the drivers side.

 

116k miles. The PO had a folder literally an inch thick with maintenance records from the dealership. I am going to see exactly what has been done to it in the morning.
Cyl 5 and 6 plugs liked identical. Cyl 6 gap was a little smaller, but not by much.
I understand anything can happen with an engine, I was just getting worried reading about all these hg failures lol

 

Also are you sure you didn't switch it

I wouldn't worry about it too much yet, it's probably something simple like a bad coil or fouled plug. You're supposed to change the plugs every 30k on these. Have you cleaned the throttle body and maf sensor? Could be a bad injector at your mileage, though it's unlikely. Best thing would be a coolant system pressure test or leak down test to either rule out or confirm if it's the head gasket.
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I will clean those in the AM. Correct me if I'm wrong, but either of those would creat a random misfire, not an individual cylinder?

 

Thank you for quick replies. I was seriously trippin over a possible hg lol

 

Random misfire could be a fuel delivery issue, bad O2 sensor, dirty MAF, clogged injectors, vacuum leak, weak coil, bad plugs, lots of things... lol
I'm not saying it's not a head gasket issue, it could still be... but it's not common on the 07 and up 4.0 engines. Individual misfire that's happening all the time is more indicative of a more serious problem, the fact that it's stumbling on cold startup is bothersome as it's a tell tale sign of hg problems on the 4.0.... that plus the cyl 6 misfire... you're justified in worrying. Could be why the PO dumped it... just saying. The things I suggested are just good maintainence practices that people often neglect on these trucks/in general. It wouldn't hurt to check the compression while you're at it.

 

I'm almost certain that Toyota updated the HG part number sometime late in 2006... a bad HG in a 2013 would lead me to believe that it could have been overheated at some point... look through service records for radiator, hose/thermostat or water pump replacement. The coolant, according to Toyota, is good for 5 years/150,000 miles. So it should still be ok. Though they may have replaced the antifreeze if another component had to be replaced, so also look for coolant/antifreeze in the service records. Look through the records and see what you can dig up.

 

Did the maintenance log say when the plugs were last changed? If it's close to the 30,000 mile mark I would just change them all, then clean the MAF sensor and throttle body. All of that will take you maybe two hours tops and will give you a fresh start. These trucks are so easy to DIY the maintenance...there is so much info on this forum and a lot a great people here will help if you have questions.

 

2013 DCSB owner here. Had the same issue as the OP about a month ago. It was a bad plug. Changed them, and problem solved.

 

Thank you all very much. I am a mechanic (I definitely don't know everything) and I was literally planning all of these things for today. I will check the service records now. Again, thank you for the replies.

 

Just went through the records and didnt see anything about spark plugs being done or a radiator / thermostat. I am going to replace the plugs, clean MAF and throttle body, and replace air filter. I haven't been on any firums in a long time. Not since i had my Volkswagens ( I had a Corrado SLC and a Mk2 VR6 GTI). People on VWVORTEX seem to flame people for any honest question. Thank you guys for not doing that. I understand what can cause misfires or other issues with an engine, but I also understand that some engines have common problems (05 and 06 hg as discussed earlier). I am going to get my parts now and will post updates. Again, thank you for your input.

 

As you know, the issue is especially apparent on cold starts. The misfire moved. I am very relieved lol. I actually switched cylinder 4 and 6 plug and coil. I was removing a Ford 460 yesterday at work so my mind was still thinking that way.

 

Any updates? @SoCal_PreRunner

 

All i had time to do on Saturday was replace the plugs. So far it has been great. Thank you all for input!