Burnt Valve?

Sounds like you're in good hands. Good luck, report back!

 

Thanks for the update @alexwlkr32 . Looking forward to what they find and what determination is made as to the cause.

 

Got a text update today. They'll be replacing the one cylinder head, valves, and all related gaskets. Sounds completely spot on with the other couple cases that have been floating around that flagged the same error code.

 

I'm still wondering what exactly failed and why. My guess is; they don't know.

 

@Chew, Same, mainly for the purposes of understanding that if it's not a revised part why won't it happen again? I'll try and catch up with the tech when they're all done.

 

Burnt valve suggests the valve wasn't closing completely. Which could be an adjustment error, of there's something to adjust.
Or maybe the VVT?


I wonder if this is somehow related to the guy the other day with machining shavings that presumably came from the head.

 

@Trident904 had this same issue I believe.

 

I had air/fuel mixture issues from day 1 on the truck. Constantly in and out of the shop for the first 20k miles and Toyota would tell me it was all normal. I was running a scan gauge and watching and logging the air/fuel mixture constantly. The truck ran super lean all the time and was worse when the Atkinson cycle kicked in. This caused CHT to climb and stay hotter than normal. Toyota opened up a corporate case on it and still found nothing wrong because they claim that the engine is designed to do that.

When I installed the OVTune around 21k miles in the late summer of 2017 my air/fuel mix problems were resolved and only got better once the tune file that killed the Atkinson cycle came out. My CHT’s were normal after this but apparently the damage had been done and at 53k miles I took the truck in due to excessive valve tap that increased and decreased with RPM changes and they confirmed burnt valves but refused power train warranty due to the truck being modified. They did however give me $28k on trade for it and I bought a 4Runner TRD Offroad. The 3.5 does not belong in these trucks.

 

Toyota is... astounding, sometimes

Did you tell them you’d tuned it or had they figured it out on their own?

 

It appears that this problem appears fairly early (approx 50k or under) if the motor has this problem. If it is an air/fuel ratio issue causing the motor to run excessively lean it makes me wonder why cylinder #1 is only affected in these cases.

 

Odd that there's the common thread. One of the threads posted in here seemed to indicate a valve spring being the root cause

 

Nope, the tune is undetectable by the dealer. Once I put the tune in, my mixture issues and lean running were resolved.

I flashed it to stock tune in the parking lot before I traded it and sold the tune kit to someone else.

 

Oh. So what mods did they deny the motor repair for?

 

Suspension, 35’s, snorkel, armor, skids, etc. They declared it “highly modified” and said that those modifications alone caused the problem, yet completely disregarded the fact that it had 4.88’s, a stage 2 clutch, and heavy flywheel.

 

Funny, since you could tow 6,000lbs the entire trucks life, causing far more strain on your motor, and still be warrantable. Toyota’s warranty is useless if they deny it for nearly anything

 

They wanted to keep the truck and have a corporate tech come look at it, but at that point I was just done and the sales manager happened to be walking through and asked me if that was my truck outside and offered me $28k to trade it, so I said hell yeah.

 

To be honest I'm pretty underwhelmed with some aspects of the truck. Granted this is the biggest issue I've had (rightfully so with only 25k miles), but seems there's a lot of poor design/mechanical decisions made - the transmission tune, Atkinson cycle, pretty high occurrence of random TSB's, etc.

The only thing that has me holding on is I'm happy where the Fox 2.5 DSC got the ride manners and I know I'm good warrantee wise for at least a little bit longer, but once the warrantee is up I'm probably going to trade in. Hopefully the new 4Runner will be out at that point or something else promising comes along.

 

I agree, I want this to be great truck and I currently have no issues with mine but long term reliability is questionable. I have a 100k warranty so I have time to see how these trucks do before I decide to keep mine or not.

 

Man, no shit. They seem to have actually performed proper troubleshooting and came to a conclusion. I would have expected that they told you it's normal and expected behavior or immediately blamed excessive abuse due to off-roading citing dirt on your tires.

 

@Pilsner , all I got was a quick text update about the fix, so I imagine when we chat in person they'll give me a more detailed explanation.