Do your 3rd Gen. valves float on 87 octane fuel ?

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I am not a mechanic but I do remember "floating valves or pinging" in older engines when fuel octane was too low and lugging at low RPMs.

At about 2,700 miles now ... I have noticed this maybe 6 times ... when engine lugs right before down shifting ... the valves appear to "float or kinda ping" ... like the 87 octane fuel was is low.

I use several good brand name fuels and when I use 87 octane in general, this happens. This happens with all 87 octane fuels that I use (i.e. Chevron, Quick-trip, COSTCO, Shell)

My next step is go to 89 octane fuel all the time and see if it continues. I will post my results later.

Again, I am assuming that it is valves ... I work on my cars ... but am not a mechanic ... if not the valves, what is it ... ???

Do any of you all have this situation ?? ........ Thanks
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Doesn't the V6 have a direct/non-direct injection fuel injector system, the pinging sound might be the direct injection at work...

 

Pinging and valve float occur on acceleration, not deceleration.

 

Most guys run 87 on 2nd gen and this gen with no issues, I don't think Toyota would rate it for 87 if there was an issue, though I know testing was done on 91. I ran 93 on my 15 and 11, but always seemed like a waste of $. Running 87 for now with my 16 but interested to see what everyone is running/thoughts.

 

Valve float and ping, also known as detonation, are two different things.

In modern engines valve float is basically a non-issue. It occurred in the days of heavier top end parts and limited spring action at higher RPMs. Today's advancement in metallurgy and lighter valve trains, as well as RPM limiters, have made valve float basically impossible to achieve on a newer engine.

Detonation is probably what you are experiencing and can indeed be harmful to your engine. It commonly occurs during acceleration when using lower octane gasoline in hot weather or when towing or hauling. Again, modern engines can typically manage this by automatically retarding the timing. You'll hear a few pings, then the engine will adjust, and it will go away until the next time you accelerate and again create the condition. HOWEVER this can occur more frequently when not using gasoline of sufficient octane. Higher octane gives a more controlled flame front to the fuel/air mixture, thus avoiding it igniting too quickly, which creates the pinging sound you hear. If it is indeed detonation you're experiencing, and not some other issue, a higher octane will control this issue. If you're at lower altitude it's entirely possible that 87 octane is too low, especially in the summer. Try 89 octane and see if it quiets down.

 

...^^^... Yes, this does happen when I give it gas ... just before it down shifts ... I should have been more specific on that.

 

Does it coincide with high humidity?

 

...^^^... This makes sense ... 98 degrees today ... on a slight hill under a load ... about 1,000' above sea level ... and 87 octane .

And I do notice it more now on hotter days too ... so, 89 will be basically better in hotter whether ... got some ideas here ... thanks.
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...^^^.. Yes ... it does ... in heat & humidity

 

Do you have access to non ethanol?

 

I started out running reg , now I run super.

It really calms down the rough idle and transmission shifting.

 

...^^^... splitbolt ... it's hard to find in Atlanta area ... that sounds like a good idea though

 

...^^^... I am going to 89 and see what happens

 

This engine, unlike the previous engine before it was engineered souly for 87 octane, you may be just experiencing the transmission shift logic toyota uses. I run 89 personally due to my experience with the engine so far and it seems happier with it, but its trial and error as most believe its flushing money away using anything but regular grade.

 

If you can find it, try some 87 non ethanol. It might give a clue as to whether or not the blended gas your getting is water saturated or if it's just octane.
Water saturation leads to phase separation which can lower the gas portion of the blend by up to 3-4 octane points.

 

If you're having pinging or detonation issues then you should have it looked at. There's enough electronic wizardry on all new engines to prevent that.

But, if you are hearing pinging, it's the sound of the fuel air charge igniting long before top dead center. Not the valves snapping shut or floating. What is loud on these engines is the direct injection. All DI has an audible ticking and it's louder than port injection, but these are little louder then others I've heard. I'm not sure if it's lack of sound insulation or the units themselves.

 

Ethanol is the root of all evil in gas engines....

 

The damn corn lobby.

 

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This sound sure sounds like the old days when the "valves knocked" when the octane was too low.

Lots of good ideas and suggestions above and I will increase octane this summer and see what happens.

Yep ... I have never liked "corn gas" and what it does to the engines and seals & etc.

I would like to buy "real gas" like splitbolt said ... but it's hard to find here.

Thanks
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You shouldn't need to increase your octane. The knock sensors pick up the sound signature and adjust engine parameters to compensate a poor grade fuel. Even cars that require 91 will run on 87 with a very neutered map. If it's knocking there's something wrong and it should be looked at.