#6 Cylinder Misfire

Number 6 cylinder misfire code on 2006 Tacoma 4.0.
Started running very rough and activating check engine light.
Took to the dealership and they replaced all plugs and reset CEL.
Truck ran great for a day and same thing the next morning.
Changed the coil packs and reset the light. Again, truck ran fine for a day or so.
While cleaning the mass air flow sensor I noticed the coolant was a little low.
I’m taking truck in this week. I think the head gasket is blown and leaking into the #6 cylinder.
I’ve also been hearing a sound behind the dash like fluid sloshing around.
Bought new in 2006 and has 306,000 miles on it. Oil always changed at Toyota.
I’ll update as I find out more. Will definitely repair and keep driving. Just put on new tires and brakes all around.
Will decide on doing the heads and valves vs engine replacement based on estimate.

 

Take your oil fill cap off and look at the backside of the cap. If you have a white creamy pudding back there, a head gasket is certainly going to be an issue.

 

So early 4.0s at this point are known to have issue with the head gaskets (more so 4runners) and 80% of the time they start as a cold start misfire on cylinder 6.

best course of action is a leak down test. If it’s found the engine is bad, at 300k + miles a low mileage used engine is likely your best bet. A 2010,2011 motor would be the best bet. Head gasket issues are rarer on the later 4.0s. 12+ might work, but the secondary air injection system means theres some holes on the head that would need to be plugged

 

Sounds like a solid plan to me. Good luck!

 

If it ain't a head gasket which I'm leaning towards it is given your year, mileage, and the sloshing sound you referred (my suspicion on that is low coolant in the heater core system leading to air entrapment and gurgling) but if it's not a head gasket (and for your sake I hope it isn't) it could very well be a intermittently sticking, or leaking injector on cylinder 6 I had this happen to me on a first gen.

 

If the sloshing sounds like it's pretty much in front of you, the way mine did, it's the head gasket.

When my truck was cold, it stumbled for a few seconds then smoothed out when started.

Nice job on getting 300k on it before it popped. Mine lasted 238k with regular maintenance.

Good luck.

 

Nicely done OP to get to 300k miles.. Impressive for any yr/any vehicle before this likely HG failure. Slap a used lower mileage motor in there and drive on.

 

Found out today that the head gasket is the issue. Besides replacing the water pump at 100,000 miles, I have had no other major mechanical issues with the truck. 306,000 miles.
I’m considering putting in a JDM engine or a Jasper remanufactured.
Either option is very expensive, but the truck is too nice not to fix. My son will be 16 in a few months and I plan on giving it to him.
Anyone have any experience with Jasper or JDM engines?

 

Why not fix the head gasket instead? Unless you physically can’t do your own maintenance these trucks are extremely easy to maintain.

 

Agree, next best is a used taco engine from a salvage yard.

 

I considered it. Just figured with 306,000 miles it might be better to put that money towards a low mileage or reman engine.

 

Or do a compression test. Why waste money if you don’t have too. A head gasket maybe all this engine needs.

 

Update on the 2006 Tacoma. Plan on keeping it for years so decided to put a remanufactured Jasper engine in. My son turns 16 next year so this will be his first vehicle. Ordered a new Tacoma last week.
Price of used trucks are through the roof so it was worth it to get it going again.
Engine has a 100,000 mile warranty and 36,000 labor warranty. Of course, lots of fine print.
Engine is in and runs like new.

 

300K miles on any vehicle is a pretty good run. It's worth keeping it on the road.
Good luck with the new engine.

 

at that mileage doing a fix

is just waiting on something else to go wrong

if U r planning on keeping the truck

look at the long game

goin in now................+ goin in later is going to cost more

 

I tend not to hear good things about jasper engines or engines that have had the blown head gasket repaired. Junkyard engine from a newer truck is the best option

 

12+ engines can work. With 12-15 header gaskets, 05-11 studs, and URD spec U headers with O2 simulators it worked just fine
The spec u headers block the holes on the block perfectly only problem is it won’t pass CARB smog

 

My son inherited an 08 taco with 401 on the clock. Now has 409,000 since he’s got his license… also Iv done head gaskets on many of these engines with over 200k on them and they still come in for service … if the frame holds out the engine will most likely keep going …. But glad to see it’s still in the family