More than one of these 4Runners have blown out a spark plug. My other theory is that sometime in its lifetime a mechanic or DIY'er overtightened the spark plugs. The heads are aluminum and the threads are soft where the spark plug threads are steel. It'll strip them right off and then only takes a single event to shoot that plug out under 180 PSI from the cylinder! Your garage did the right thing and repaired the threads but it could happen to other cylinders if those threads are damaged as well.

Okay so I had the spark plugs swapped; they were "rounded" but didn't look horrible. I was already having a local shop do the diff fluids Friday as a favor for some free computer work I did for em and while mentioning the pinging they offered to do the plugs as well. Although of course with my bad memory I forgot without looking down in the cylinder.

Beyond that, the injectors were replaced like two years ago, the maf (denso) was cleaned about 6 months ago but it wouldn't hurt to do it again. Air Filter should still be good, fuel filter should be good. (Based on time)

From talking with the guys at the shop more I dumped a whole can of sea form into a half tank of gas and, after driving 10-20 miles, will do a couple of "Ferrari tune ups". Also going to do the seaform through the intake, gotta find the spray version. Lot of stuff is still out of stock a lot in my town.

I usually drive her like a grandma and I guess never hitting high rpm's would cause the build up?

Pinging to me = pre-detonation. It is affected by octane, fuel mixture and timing.

As others suggested have you seen live data on the last 2 (these engines cannot make anything useful of higher octane fuels so they are a waste of money)?

You can use something inexpensive like Torue Pro ($5) for android/ios along with a blue tooth odb2 connector to monitor data.

I'd be interested in seeing the A/F mixture and timing along with STFT and long term. There are clues there as to what is happening or not happening correctly.

I agree with someone who said an otherwise healthy 5vz will not ping whatsoever under any type load. Mine does not either, thank you Yota Gods.

Seeing what the plugs looked like color wise to see if they are burning evenly would have been nice.


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Oh sorry, I mean I still have them I was actually going to post a picture once I got home.

Do that please


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I do have torque pro and an adapter. Should I wait until I run the premium out to try to get any data? Right now she has just under half a take of mostly premium and a can of seafoam.

And yeah I know they can't take advantage of premium but my understanding is that a higher octane makes the fuel more stable and therefore less likely to predetonate. Normally I always run non-ethonal.

Photos up. Unless I am mistaken I think these really don't look too bad? Edit, cylinder closer inspection it looks like some of the double prongs are slightly bent although I don't know if that's just how they are new or not.

Some look dark and some look like they have no signature at all. Your gap looks big on a few also.

Do the new plugs make a difference? Overall they look lean. That’s what happens when all 6 cylinders are controlled by one O2 sensor. If one cylinder is rich it leans out the entire engine

Example of a good plug with 30K miles on it.



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Those plugs don't look terrible, but the gap does look a touch wide. If you have a gapper for dual electrode plugs you can check them.

Taking a lot of short trips and not warming the engine up will cause carbon buildup.

Premium fuel is less likely to detonate because of the octane rating. Whether it's ethanol free or not does not matter, it's used to increase octane but the engine cant distinguish between 87 octane using MTBE and 87 octane using ethanol. Premium does have more cleaning additives.

Does the shop have a borescope you can use? If there's a huge amount of carbon buildup you'll be able to see it.

Your engine is running lean. The center ceramic insulator should have a 'mocha' color to them on these 4Runners. That confirms for me that your engine is running much leaner than it should be and causing the pinging and it's not the ignition system. Something is cutting out fuel when it should not be. I would take a look at your fuel trims both while driving (LTFT) and at idle and post them up here. I think you're going to find a large negative -% value. Seeing that lean conditions are quite rare (and throwing a true lean code even more rare) there may not be a whole lot of archived information on what to fix. The sensors that control fuel are listed below, in priority to the ECU:

Front O2 sensor
MAF sensor
Engine Coolant Temperature Sensor (cold starts)

Also, any damage to the prongs is also a warning sign. I doubt they were like that out of the box or you would have noticed them.

Alright so the LTFT never really went above 1.6 but this was only a 10 minute drive. I'll try to get some more data after work. Also, when you saying a warning sign, just a confirmation of predetonation? Lastly, if she is running lean would that cause the exhaust to smell noticably off?

When he said warning sign there are a few plugs with bent/not centered ground arms.

All six of my plugs had the exact same color yours are anywhere from ash gray to pure white without a hint of brown.

Can you repost the pictures closer and looking more downward? Do any of them have a hint of brown on one side (intake side of plug)?

Check your LTFT at the end of your drive when the fuel maps were updated.




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You know what I think they might actually because the last time I was there I heard them talking about looking inside of something "with the scope". I have to give them a call and see if we might could take a peek inside.

I do have a general update for everyone following: after some guys here suggested it I dumped in an entire can of seafoam into the tank which had just under half left. I drove around for a while, driving somewhat spirited occasionally really given it the beans here and there. Sunday morning I filled up with non ethanol, regular octane, 87 or whatever it is, and had to do a lot of driving for errands and up to the big city to get something from Ikea.

So here's the main update, since filling up with non-premium I've only heard the pinging what I believe was just twice. It was significantly more tame and just for a split second or two. Today I do not believe I've heard any pinging. But here's the other thing, and obviously I would need to go through a whole tank to really know 100% for sure but just at a glance it seems like fuel economy is way up. I hit 85ish miles at the 3/4th tank mark where as normally it's like 60-65 miles.

I'm definitely not calling it for sure yet, but perhaps it is improved.

Since the other guy mentioned the mass air flow sensor I'm wondering if the one I bought from Amazon might be a dud? No it wasn't just a random off-brand one, it said it was OEM and they were 10 or 20 comments, reviews, they all said that it appeared to be OEM. Twas $90 so I figured it was legit. Maybe it was a cheapo?

A reliable treatment for such things.

Sea Foam SF-16-2PK Motor Treatment Multi-Use, 16 Ounce, Pack of 2, 16. Fluid_Ounces
Amazon.com

Rinse and repeat if necessary. Good luck!

I've also used B12 Chemtool before with good results.

I suppose it could have been fake but not likely. Your LTFT looks normal, which is very odd. Pinging but fuel trims unaffected? That's a new one for me. I think the color might have been off on my last screen I looked at since now that I am home, the plugs look more brown than before. They looked stark white on the last screen I was using.

Let's keep going the easy route and run seafoam for a while. Was it here we mentioned Seafoam spray as well? It'll do what Seafoam in the tank is doing but a whole lot faster. I used to do that, 1/2 in the tank and 1/2 through the engine via a hose with vacuum. It really is a lot of fun.