Acceptable Number of Misfires?

Update 2: Dealership found the issue, bad gasket on the intake manifold. Should have it back Monday. Gotta say I'm pleasantly surprised, I never thought that they'd take the time to chase down an intermittent misfire that wasn't throwing a check engine light.

Update 2: Taking the truck to the dealership, the misfire has gotten a lot worse. Still not throwing a code, but you can feel the truck hesitating badly and then bucking a bit when it happens, and I've been logging with OBDLink and found that 90% of them occur between 3k and 3.5k RPM, and between 30%-60% relative throttle. Short term fuel trim for bank 1 shoots up 10-12% when the misfire happens. I just did an 8 minute round trip to Dunkin after the truck had already been warmed up, and got 36 misfires. Wish me luck.

Update: Based on the evidence that I've seen posted here this really isn't an issue, so I'm going to just try and forget about it. Thanks to everyone who posted for helping me to understand.

TL;DR - My truck sometimes runs a little rough, so I used OBDFusion to log how it is running and found that it has what I think are a lot of misfires, but never illuminates a check engine light. Is this fine as long as it never throws a CEL?

Hey everyone, my 2019 Tacoma with ~19.5k miles has been experiencing a little bit of rough running, particularly noticeable as a stumble during acceleration right where the "power surge" is when the acoustic valve opens. I used OBDfusion and found that it has a lot of misfires, even when the engine is fully warmed up. I'm seeing 15-25 misfires per hour of driving. The check engine light never comes on though, and the $06 monitors show a green checkmark for misfires despite the high count. This happens with both the stock tune and with the 2.0 OVtune at about the same frequency, so it's an issue with the truck, not the tune. Resetting the learned values doesn't seem to make a difference. I have been running 93 octane fuel since December, usually from Irving or Shell.

I also own a 2016 IS350 which has a similar engine (2GR-FSE) and similar miles (18.5k), so I ran the same test with OBDfusion on that car. I did a full hour of mixed driving this morning, and it had 0 misfires in the $06 monitor at the end of my drive.

I don't think the dealership will do anything until it throws a code. So I ask the community - should I be worried? Will this shorten the longevity of my motor? What should I do next? If any of you guys who are familiar with tuning an engine ( @OVTune @lapoltba ) would be willing to look through a datalog and advise, I'd definitely pay you for your time.

Thanks!

-Sean

EDIT: attached a screenshot from the end of last night's drive. This is on the stock tune, which Ia been running for a couple of days now.


This was from a warm start (truck had only been off for an hour) and was over the course of an hour and twenty minutes of mixed highway and back road driving. For some reason the screenshot cut off the data for cylinder 6, but you get the point - based on the math, there would have been 4 misfires in cylinder 6 during that ride. Running the stock tune for the past several rides before and including this one.

 

I would try a higher octane fuel to see if the misfire count goes down.

 

I should have added, this is on 93 octane, which I've been running for several months. I'll update the post. Good point though.

 

This was discussed in the ov tune thread but good luck finding it in that dumpster fire. I think Matt said Toyota says that a high number of misfires is acceptable. They set the limit that throws the code. That being said, my truck doesn't like when the transmission shifts down and places me at 2500_2800 under load.

 

Was it worse with the lower octane or is it not related?

 

I actually don't remember experiencing it when I was stock and on 87 octane. I guess I could try putting in 87, but if anything I'd expect the issue to get worse.

 

Interesting, I'll test out my google-fu and see if I can find it. I did see a lot of hits in that thread when I searched, but the first few posts were about a guy who was pulling logs while cold cranking cranking the motor for some reason, and I rolled my eyes and closed it. lol

I wasn't particularly freaked out about the issue until I saw how misfire-free my Lexus is. That car is stock and also runs 93 octane, so given how similar the motors are I thought the behavior should be about the same.

 

Yeah crank position sensor for the win

 

I definitely feel some misfires in the same range, stock or ovtune, doesn’t seem to care about octane either. With m/t.

I really wonder about the interns they used to make the Tacoma’s engine code

 

I remember seeing misfires on my vehicle too a while back. Guess it’s normal for this engine.

 

Seriously. And if you drive a 2017+ IS350 or GS350 with the same 2GR-FKS the engine feels so much smoother and stronger. I know those cars require premium fuel but damn, why wouldn't Toyota just use a version of that tune so that the trucks would drive the way that they're capable of.

 

If you can smell gasoline near the exhaust, it’s misfiring too much

 

I suppose that could work, maybe mine is reading off. I thought they fixed that issue on the 17/18 trucks though. Can't hurt though, it's an easy enough swap.

Ok good to know that this isn't unique. I may try the crank position sensor swap anyway just to see if it works. For science, lol.

 

Maybe. Truck always ran fine even with the misfire counts showing up. My truck is completely stock.

 

Mat (OVTune) has said that the "misfire" count provided by the ECU does not necessarily represent actual misfires, but that the conditions to cause potential misfires are present.

 

When misfiring, what do your fuel trims look like along with O2 values? You might need something more to get the upstream values correctly since they're AFR type.

 

I would not be alarmed at all.... 8/9 is nothing to worry about. A "misfire" according to the ECM is not the same thing that you and I think of as "knock". Try a higher octane as suggested already and see if it changes.

This is the problem with information, it's useless out of context.

 

Thanks man, I appreciate the input. That's what I was hoping for - unfortunately I'm already on 93, but if this doesn't look like an issue I'll try not to worry. I just got freaked when I saw on the OBDfusion dash board that the indicated misfires were popping up right when I'd feel the stumble.

 

I've got the the OVtune logger on my laptop, I could pull a log there and see how it looks.

Only issue is I don't know shit about engine tuning, so I don't really know what I'm looking for.

 

BS..