spark knock?

Very odd, my 2017 3.5 V6 Tacoma has what I suspect to be " spark knock".. The reason I state this during hill climbs/ underload I can hear what sounds like a rattling sound from the engine. I'm wondering if the high pressure fuel pump is not delivering the correct amount of AFR?

I do have a torque OBD2 reader but i'll need to monitor that in real time.

 

I have heard similar in my truck, its a 6MT, and noticed that if I run mid or premium fuel it doesn't happen. I honestly think it is what should be required with our engine. I also notice a good power difference running premium.. its a bit more responsive. Give it a shot and report back!

 

I'm running 87 octane ( regular), the truck was always advertised as being able to run at that grade or was designed to. I don't understand why its bogging down/ knocking?

Maybe I should just reset the computer by pulling the battery? I mean it doesn't always happen. But I'm noticing it more.

 

For some reason they put in the manual for these trucks that engine knocking is normal and no need to be concerned. ?? I still don't believe it. But mine does it too, seems to get better with higher octane gasoline. I'll look for the other posts about this issue.

 

I know its advertised as such, and I believe that the engine will protect itself from damage, but I also believe that it does run better with higher octane fuel. After all this engine is in many a Lexus, and they require premium. Fill up with a tank of 93 and see how she feels.

 

Ping ok. Knock bad. Pull out timing and performance will be worse. Probably wants to run on 89.

 

I noticed when filled up at the pump it less of an issue as the system is fully pressurized. 1/2 tank or less, it seems like the high pressure fuel pump works harder and this is when the spark knock occurs.

Yeah, I'll try her on 89 and see what happens.

 

Any updates on this? Noticed a rattle in my engine earlier this week. Thought it was rod knock at first and got worried. Pretty sure it's detonating.

 

Interesting. I have the knock or ping sound when I'm loafing along about 35 and lightly accelerate it will do it every time. I also feel the truck drives better with a full tank but I don't know why that would be. Extra weight seems counter to better performance.

 

As I recall, this engine came from the Lexus branch, which was originally tuned for higher octane(91).
These higher compression engines need higher octane to prevent knocking.

For the tacos, they redid the whole engine heads.
They added VVT(forwards and backwards) and they tuned it for 89 octane.

I bet money that if you do add 91, you allow the engine CPU to delay
combustion before you detonate. So when your engine is not running Atkinson and
running the full 11.8:1 compression ratio, you will feel more power.

 

You can’t hear the injectors while driving. I only hear that when idling

 

Bingo!

 

Read about the oil catch can and lower power while reeving up the engine. Get one.

 

Mine does the exact same thing at these speeds when going from a light load to acceleration. I dont think it is the injectors cleaning themselves. It is distinctly different than the injector sounds. Like a year ago I asked the same question on the forum and didn't get much of a response.

Could totally be placebo but I changed the grade fuel I was buying and it seemed to help

 

No, ive been working on cars for over 15 years. This is distinctly pinging/detonation or some sort of valve train rattle that is going on from in low RPM/light load.

 

I believe I have what youre hearing also, in fact the sound seems distinctly like Chevys notorious LS piston slap I had in my C5 corvette, which was caused by them Teflon coating the blocks this decreasing the piston/sleeve tolerance to make up for this they used ever so slightly smaller pistons and an expanding skirt, problem was until that skirt was properly lubed it cause a slight rattle or slap, and my 3.5l sounds the same, I highly doubt its the same problem, maybe it comes from the little bit that gets pushed back out the intake valves for our make believe "Atkinson cycle"

 

I filled up with premium today and will see if the sound is still audible. It seems as if it has been getting worse.

 

If I run 87 octane in my 4.0 I will get spark knock under acceleration. It does not happen with 91 octane. I usually live with it when the price difference is 40 cents... if the price difference is like 20 cents I usually buy 91. I seem to get a little better mpg with 91, so it isn't a total waste.

 

Any results?

I notice the same issues with mine. My 4.0L pinged on 87 as well. Maybe I'll switch to 93 and see what happens for a bit. Rip wallet.

 

Still makes the sound..

Im starting to get concerned..