2015 V6 Spark Knock/Pinging

So tech , how would you handle this problem if it were your brand new truck ?

 

Someone correct me if I'm wrong, but that's usually what higher octane fuel will correct (pre-ignition). Although they sound the same, pre-ignition and spark knock are two different things, both can be equally detrimental to your engine though if they're bad enough.

From misterfixit.com (first popular hit on Google on the issue 'spark knock vs pre-ignition)

"WHAT IS DETONATION?
Detonation (also called "spark knock") is an erratic form of combustion that can cause head gasket failure as well as other engine damage. Detonation occurs when excessive heat and pressure in the combustion chamber cause the air/fuel mixture to autoignite. This produces multiple flame fronts within the combustion chamber instead of a single flame kernel. When these multiple flames collide, they do so with explosive force that produces a sudden rise in cylinder pressure accompanied by a sharp metallic pinging or knocking noise. The hammer-like shock waves created by detonation subject the head gasket, piston, rings, spark plug and rod bearings to severe overloading.


PRE-IGNITION

Another condition that is sometimes confused with detonation is "preignition." This occurs when a point within the combustion chamber becomes so hot that it becomes a source of ignition and causes the fuel to ignite before the spark plug fires. This, in turn, may contribute to or cause a detonation problem."


It's a good read if you have a few minutes...

http://www.misterfixit.com/deton.htm

 

This sounds exactly like they told me except for one part...They said it wasn't hurting anything.

 

Well, I've heard that too and it's probably true if it's a minor occurrence. But it's no secret that excessive heat is a motor's worst enemy, so it makes sense that if the issue is bad enough that it could lead to problems down the line. When I was getting bad spark knock from having the wrong plugs with my supercharger, it was LOUD pinging, like someone had a jar full of marbles in my engine bay and was rattling them like crazy when I'd accelerate especially if I was in a high gear with lower RPMs. It wasn't pretty. Again, colder plugs resolved the issue for me but that's because it's a common occurrence with supercharged applications. I've heard mixed opinions about putting iridium plugs on N/A motors but if the spark knock was bad enough, I'd give it a try if it were me.

 

It's the best option I've heard so far.

 

I was hoping tech would offer some advice.

 

Did the truck do it when it was new or develop this after a while?

 

Didn't notice it until about 25k.

 

Then I'd clean the carbon from the top of the Pistons and see what happens. Lexus has a documented procedure.

 

I'll look into that, thx. I wonder why dealership didn't offer this info ??

 

Plausible deniability? And it's not that widespread of an issue. Out of the hundreds of thousands of trucks sold, very few have had this issue.

 

I agree with the colder plugs = more chance for carbon buildup. I would be willing to try that before getting rid of the truck if I needed to. From what I read a slower developing burn would put the peak of the flame pulse later (hopefully?) in the cycle reducing the spark knock intensity some? Sort of similar to the premium gas principle? Cooler t stat = cooler air (hopefully?) fighting the optimum knock conditions some?

I have the truck back now and test drove it a few minutes ago without hearing the spark knock. As far as making a mountain out of a mole hill.....well read below.

The Master Tech verified the spark knock with a scan tool and I have two printouts of freeze frame images displaying three graphs each: Vehicle Speed, Ignition Advance and Shift Status (what gear it was in).

He flat out aknowledged that it was happening in first and second gear primarily under the test conditions. I liked this guy, he was on board with reality, my kind of guy. I was told that they looked into the cylinders with a scope and did not see an abnormal amount of carbon or a difference between cylinders. They chose to use a solvent to clean the little that was in there, "crank and let it blow out into rags" and change the oil. The intake tract was cleaned (broad description offered). I guess that means solvent spray. Funny thing is that i just had my 30k service and they said they did that................

On the service receipt it says "Tech contacted TAS (CASE#*********) and TAS has noted that this is a characteristic of the engine type (4.0L engine) and has updated software."

I don't know if I believe that only a cylinder "clean out" and the spray cleaner in the intake has made this better, but I will see how it does tomorrow. I am thinking they updated or changed something that Toyota does not want the masses to know (watch out, conspiracy theory!!!!).

The knock correction (Knock Feedback Value) is -4.6 on the after service snapshot and -2.6 on the original snapshot. I don't know what they did in all but it helped. Tomorrow I will have more time to drive it.

 

It's probably a can of top engine cleaner. GM makes a good one but all manufactures have a specialized cleaner for this and all the flush chemical company's that dealers use make one. It usually gets sucked through an intake port while the engine is running and cleans the back of the intake valves and combustion chambers.

 

All the Toyota "explanations" aside, when you are vehicle shopping do you look for one with a "normal spark knock"? Hell no, no one does. I stand by my bitching that it should not do that and if it does it's bad for the engine. if it was normal you would hear it in a lot more new engines (by design of course).

What is cool is how everyone here pools ideas and experiences and that a toyota tech is listening to the consumers reports. I'm just one man, but I think the buyers don't want to hear it.

 

I haven't read all replies, but I noticed a similar knock under load. I'm in a '13 with 35k miles. I've moved over to ethanol free gas, and the engine runs much smoother now. My MPGs have increased as well. I lost 25% tank range when I lifted and added over-sized tires. I've reclaimed 15-20% of that loss by watching my driving habits and running ethanol free gas.

 

These are the snapshots

 

That's pretty cool. Sounds like your getting a tune for free.

 

That is neat. Next time at dealer I am gonna ask for them to hook it up to the tech stream.

 

Hopefully this will take care of your problem. Glad for ya.

 

Yea me too man. I have an attention to detail too and it would annoy the piss out of me if this happened with my pickup.....