P11EC00 error code update

Based on which facts? We have been looking at engine ops parameters for many years before and after tuning and yet to see lean conditions at normal operation.
It only runs lean on cold startup when only port injection mode is active. You can see the rpm drops after 20-30 sec.
This engine runs on the reach side.

 

Interesting, I had read that the dual injector configuration on the Tacoma was not used in other Toyotas. Do you recall if the Highlander motors employed both port and direct injection?

It's been stated that it's caused by a lean condition from a dirty injector. Since all injectors are identical and this problem seems to occur most often on Cyl.#1, I too suspect poor cooling in that area combined with a very lean condition made worse by the buildup of combustion byproducts on the head of the injector is the culprit.

Good question but somehow I'm doubting that they did.

Everyone I've spoken to have said the replacement heads and associated parts are identical to the failed one. Since this has been occurring for over 6 years and they haven't changed anything, I don't think that's the issue.

 

Every D-4S engine have duel injection, including 4 bangers hybrids
Which injector failed on that cylinder? Port or Direct?
FYI, we were running a tune on DI injectors only. Some probably still do. We never had a lean issues on it. I doubt the injector is the issue.
also, you should have seen some misfiring symptoms and possible a check engine light leading to the failure.

 

You are correct about the motor, what I read was outdated.
There was no indication of an actual injector failure.

The only error was the P11EC00 which I'm surmising was the result of the burnt exhaust valve leading to an incorrect combustion mixture. At that time I could also feel an uneven idle. From what I've been reading and hearing is the techs that have worked on these believe the direct injector is at fault as they're quite dirty. That doesn't explain why Cyl #1 unless it has inadequate cooling which contributes to the burnt valve.

 

There a cleaning cycle that runs during the hot idle to blast the carbon off on direct injectors. Dirty injector does not mean its flow is obstructed.

 

How does the computer in these determine a lean condition? I’m not aware of any exhaust gas temperature sensors. Fuel flow ? Poorly atomized fuel could run lean even with adequate flow. Not arguing a point, just curious how these ecu’s determine status. I’m still in the mindset that a valve related manufacturing defect would show up much earlier but have no clue.

 

A/F sensors on each bank <1 -reach, >1- lean ,1=14.7, 1.23 - fuel cutoff. Also, there are cats temps for each bank. ECU compensated the fuel based on A/F reading in closed loop. You can see it all while driving for about $30

 

Fascinating. As an engineer I love data and I'm wondering if this data would reflect any differences between Bank 1 & 2 since one head and presumably the injectors are now new while the other is not. I have an app that should be able to read and store these values although it may take me a bit to identify these specific values.

 

Has anyone had the issue happen twice? As in happen again after replacing the head and valves? I traded mine at 108,000m for a 4R and it had the work done at 35,500. No issues after the repair until when it was traded. I do not believe they did anything with the injectors. Wouldn't it be bound to happen again if it were injector related? (I am nothing close to a mechanic or an engineer so forgive me if this is a dumb question).

 

Atkinson cycle doesn't make it run lean. All it does is bleed off some of the air on the compression stroke.

This is my uniformed opinion but it's not fuel related. I find it hard to believe the engine would be lean enough to burn a valve and not throw a code first. I think it's a manufacturing issue in the valve, guides or seat.

 

Not a dumb question at all but one that needs as much input as possible to help guide those of us that have experienced this problem and are not debating the wisdom of keeping the truck long term.

 

This is my uniformed opinion but it's not fuel related. I find it hard to believe the engine would be lean enough to burn a valve and not throw a code first. I think it's a manufacturing issue in the valve, guides or seat.[/QUOTE]. As far as I understand all of these engines are assembled in the same plant , I believe in Alabama , so the truly confusing part is how some of these fail at 50k miles and others last trouble free north of 200k miles , at first it seemed it was only a few 2017s having this issue but now it seems it’s affecting trucks as new as 19 and maybe even newer , I was considering trading in my 18 for a 23 but from what I am hearing , there has been no change to the replacement heads being fitted to the failed trucks so I might as well roll the dice and stay in my 18 . Def a frustrating situation

 

Most burned valves are a result of lean fuel mixtures. Inadequate engine cooling more often results in seized pistons and timing issues create knock and the resultant broken pistons. Both cooling and ignition timing are much easier to track and adjust for within the ECU.

As for not throwing a code, it all will depend on where they set a threshold. When you consider it takes a burned valve and the resulting unburned mixture that the O2 sensor catches, the threshold is fairly high. It's remarkable enough to me that the sensor can differentiate between cylinders on the bank for incomplete combustion that for them to be able to detect a lean mixture would be quite difficult IMHO.

 

If this this the case, you would've ended up with more that one burn valve. Home valves were replaced during repair?
Secondary, modern ECUs will keep adding fuel to enrich the mixture and most definitely will set MEL before the failure. Did you see freeze frame data?.

 

In a lean mixture situation, it's always the exhaust valve that burns first as it's at a much higher temperature than the intake. As for how many valves were replaced, I don't know for certain but imagine that replacing a head meant all valves were replaced. I can't imagine they would go to the trouble of removing every valve, spring, retainer and follower and transfer them to a new head but I could be wrong.

 

Of course the exhaust burns first it’s much hotter but I still don’t think it’s from being lean. Most burnt valves are from the valve not sealing. Exhaust leaks by and the seat can no longer cool the valve. It doesn’t need to be lean for this to happen.

Now what’s causing it not to seal is the question.

 

I agree the burnt portion of a valve is where it's no longer sealing completely but in my opinion, that's still a result of being too hot which most often stems from being too lean. But after giving your comments some more thought, it is possible that warpage in the head could instigate a leak and if that's the case, most of these failures would show a burn in the same place on the valve. That also is one possible explanation for the problem occurring most often at Cyl #1. Unfortunately none of us get to see the actual failed parts so all we can do is speculate.

Since heads are castings and there's more variability in a casting than in the subsequent machining, perhaps there's a section near the valve seat that in some castings is thinner and therefore less able to conduct heat away from the combustion chamber. We know these engines are designed to run as lean as possible and this problem may just be random based on the casting. That would also explain why on the few we've heard back on, it doesn't seem to happen a second time. Given that everything being replaced is supposedly identical, a random variation in the castings could be the culprit.

 

My thought is the intake build up might be due to the Atkinson Cycle.

 

I think you're on the right track but not sure it's the head itself. Something is keeping that valve open causing it to burn. Could be the seat/valve itself, sticking guide, weak spring, the valvetrain, etc. I do recall one person noting the valves could rock pointing to guides.

If it was an issue with fuel I think toyota would address that issue when fixing the trucks. I'm sure Toyota knows the reason but isn't saying. It's rare enough they'd rather just fix the issue as it happens. That leaves us to speculate.

 

I’m thinking If it is a casting issue or a valve component failure and toyota has figured it out , the replacement heads and related hardware would be the improved part and it may not be noticeable to the naked eye when the parts get shipped to the dealer doing the job , so if it was a run of earlier production trucks , the repair should be permanent , I don’t think I’ve seen any trucks north of 2019 to suffer from this , or maybe they just aren’t old enough yet ? I’m also curious besides Alabama do any other plants assemble the 2gr fks stateside , because lexus doesn’t seem to have this problem from the same basic engine