2018 popped a DTC code P11FO

Truck popped a P11F0 DTC code Saturday and wondering if anybody has had any recent experience with it?

best I can come up with from older threads and google search it’s a #5 cylinder air fuel ratio imbalance port side issue.

The older thread didn’t provide a lasting resolution, but the fuel pump, #5 fuel injector, and bad plug were mentioned as changed out.
But again did not provide a lasting fix.

 

Update to issue and seeing if anyone else has had this issue.

Since my first post September 13 I have ran approximately 3 tanks of gas with fuel injection cleaners (Seafoam, and Marvel). And the Light has went off and on again about three times.

Took it to Toyota this morning while light was on again for more troubleshooting. They are now telling me it is the 5th bank intake/exhaust valve leaking.

Want me to bring back for two day of further testing to be sure and if settled they will need it for two weeks to pull engine and make repairs.

What type testing would be required to see if theirs a bad intake/exhaust valve leak?

And in your opinion should this be covered by Powertrain warranty (40,500 miles)?

Service rep couldn’t answer these questions. But did state “this is the normal fix for this issue”. So I asked “you’ve seen this before?” She stated yes and the Tacoma usually having the issue.

 

It's one of the hardest to diagnose, it can be either injector or either valve. The cylinder head always needs to be removed to check mating surfaces.

It's 100% powertrain warranty. 5 yr 60,000miles.

 

Thanks for the reply! So for testing a valve, would that be a compression test? Anything else?

And if valve (s) what’s the repair?

 

Probably it's the #5 exhaust valve,
compression test will show #5 cylinder well below 180psi (80-120 is common).
When they blow air in the cylinder to pressurize it they will hear the leak(s).

Intake then cylinder head comes off, inspection will show the burnt exhaust and maybe intake valve,

New head and a COUPLE valves and seals are ordered (not all valves are replaced, only the head every time)

Head reassembled with old and new parts,

New gaskets and head, then intake assembled to engine.

Now is your opportunity to ask about an extended warranty with the dealer or a call into corporate Toyota.

You drive away in your truck and enjoy it for the next 10+ years.

 

Thanks. And your saying negotiate extended warranty due to early quality issues, correct?

 

And say that while you have every confidence in a Toyota trained tech, you are nervous about the extent that the motor had to be taken apart to perform this repair.

Realistically the dealer would know in minutes of a big problem, and a code would be thrown withing hours or a couple weeks for minor problems.
But what the hell you have a negotiation point to get something for free out of Toyota, and some people that had this issue got their warranty bumped up for free or at a severely reduced price. Dealer cost for warranty extensions is half the cost of the advertised rate and corporate hands out free warranties just to shut up a customer and close a case file.

Can't hurt to ask and make some noise.

 

Yes sir, this rough idle, misfire, sensation has been on this truck from day one. It has just gotten progressively worse. I took it back to dealer early on within the first couple months after buying and was told “they all do that” and “it’s by design”.

I made them make notations every time I went in until the service manager test drove it and made those same statements and refuse to enter more notes.

I should have at least two records of it to go back to.

 

Does techstream have an injector balance test?

 

I think so? I don't use it personally. We switch injection modes when checking and a compression test or leak down later.

We usually have injector faults with this code, but it can just as easily be a valve.

 

A compression test may not show a valve leak, the best way to test for valve leakage is a cylinder leak down test. If it fails that test then it can be valves or rings. It is possible to eliminate the rings by putting some oil in the cylinder and testing again but this is not always conclusive. The best way to determine the cause, is to remove the head and inspect.

 

Yes, I have seen engines pass these tests with a hole in the piston though.

Edit: I also had an engine pass the cylinder balance test with the crank split in 2 pieces. It split at a 45° angle on a main journal and was still able to run... it had a funny vibration and a light clunk at times. Took a bit to figure that one out!

 

What could have caused the possible valve leak?

Is this something I as the driver could have caused?

 

You talking bout relative compression or I Hector balance? I've never used one tbh.

 

Not sure of the name other than a cylinder balance test or cylinder performance test. When doing the test the ECM and program monitor engine rpm while cutting out cylinders. Some programs will allow idle, some will step up idle. Some will allow you to pick various rpms. If the program sees a noticeable drop in rpm when cutting out a cylinder then it passes, if it doesn't see a drop in rpm then the cylinder fails.

This test if it shows anything only shows a weak cylinder or dead cylinder though... it doesn't show why. Still could be fuel, air, compression or ignition issue.

 

Injector balance is much the same. But I think maybe it measures the amp draw of each injector? Like I said idk much in depth knowledge of it lol

 

Also, not sure, but newer iterations of cylinder balance might monitor starter amp draw with the injectors off and recognize he dead hole with an amperage drop. Correct me if I messed something up?

 

I am sure there would be a code for that, the sensors all have a working range that is preset and normal. When the value changes and steps out of that norm, then it will trigger a code either indicating the sensor has shorted high or low depending on the circumstances. No test required. This is the way it works with the stuff I work on. I have not looked through the code list for the Tacoma but I am sure it will be similar.

Edit: actually, the fact that OP is getting a code that indicates a specific cylinder, indicates that the ECM is looking at cylinder response during normal engine cycling. It has coded for a air fuel imbalance. It never set a code for an injector. So it most likely verified injectors performance through the O2 sensor and the amperage draw, to trigger the specific code it did. That would be me trying to work out how the system works. The system is an step more advanced then the commercial equipment I work on.

 

I just looked through the service manual briefly. There are injector codes related to failed opens, and fuel performance problems in the direct and indirect injection. So there are specific codes that would have triggered if the issue was injectors.

 

I don't know if toyota pcm's support this test I will talk about. During my 48 years diagnosing at Ford dealers (now retired) I found their relative compression test 100% accurate for me. It found faults that a regular compression tests, leak down tests, and power balance tests did not find. The relative compression test measured the speed of the crankshaft during a 30 second cranking period. The fuel injectors and ignition are commanded off . The speed of each piston was computed and shown as a percent. Any leak/crack would cause that cylinders piston to move faster. The test would kick out if any starter/battery issues. The engine repair techs became believers after I found countless faults on engines that passed normal tests . A good example was all the 3.0L Ranger & the 32valve DOHC valve train problems . Most of those engines would pass normal tests. I think crankshaft speed can effect how some valve problems react. I also found some valve problems doing a running compression test. I would start the engine up with a manual gauge installed and watch the gauge pulses go up. Compare to another cylinder. A leak down test was my last choice for a test. Most warranty companies want that test done. A bad valve guide or seat could sit tight with no engine movement and pass a leak down test. As soon as you put motion in play issues show up. Hopefully a good Toyota Tech will use more than one test to find fault. The way Techs get paid under warranty can be tough, multiple tests are frowned on by warranty audits. In a perfect world they feel one test should find the issue. Engines can be tricky to diagnose at times. It's up to the Tech and his decisions on how hard to pursue.