Tuning Options

[SirDigby]

Originally Posted by tmontague

Will resetting the Yaris' ECU and running 91 octane for a while cause an increase in performance? Now I know that 91 octane does not give more power over 87 on the same tune, but I am asking because the 1nz ECU is constantly learning.

The 1nz if already a relatively hgh compression engine (10.5:1) and is therefore tuned to reduce knock on 87 pump gas. If you reset and run 91 or even 94 will the knock sensor etc. allow for more advanced timing since there is no detection of knock?

the manual states the optimum fuel to use should have a RON ratting of 91
that being said, if you run on 87 the engine is retarding; even though we use the RONxMON/2 method. but it's still a guess where in the mix you end up. it is acceptable to run on this, but you should buy the highest quality possible. with fuel at or below $2 a gallon for 91, why not.
where I live we also have 85. I KNOW my car came with a full tank of it when I bought it. it took about 3 tanks of 91 to get it running properly. I always run 91. (ethanol-free if I can find it)
people might say it's a waste of money; but if you are going to use synthetic oil, synthetic trans fluid, good tires, and you don't cheap out on the products you use on your car, why would you buy cheap fuel???
duh.

[NYC-SE]

Originally Posted by SirDigby

I always run 91. (ethanol-free if I can find it)
people might say it's a waste of money

People are right. And we're off topic.

[tmontague]

Thanks Digby, I'm going to look into my manual and see what it recommends as I don't remember it stating 91. I understand your parallels between synthetic oil and higher octane fuel. However I personally don't draw the same conclusion as syn oil has better extreme cold start performance, and higher octane fuel isn't necessarily cleaner (unless you believe industry rhetoric) but if an engine isn't tuned for 91 then it just raises the detonation point to a useless level that you cannot take advantage of.

Originally Posted by NYC-SE

People are right. And we're off topic.

Digby simply answered a Q I posed on my own thread since the tune Q was essentially beat down and concluded.

Although his answer differs from the ones above him, he is the only one who -although subjective - explained his rationale. I posed the Q about octane gas with a theoretical reason as to why it may possibly have an effect specifically in the Yaris. Although the answers are appreciated, simply stating yes or no doesn't truly answer or explain each persons specific reasoning, it simply throws out their opinion (whether correct or not).

With that being said, can anyone poke holes in my theory I posed with the Q or explain as to why 91RON would not allow for the Yaris to advance timing and improve performance? (I still have to check the user manual recommendation) My only guess for 91RON having no effect would be if the Yaris ECU is not tuned to advance timing past that of 87RON, then it would become a complete waste of money.