87 vs 91 Octane: LC vs LX570

[bjorn240]

I’ve been Googling. Looks like both Knock Correction Learn Value (KCLV) and the Knock Feedback Value (KFV) are PIDs and can be gotten via something like a Tonwon.

 

[NMC_EXP]

Octane relates to pre-detonation. Before engine mgmt systems higher octane allows timing to be advanced without pre-detonation. Way back when some of the octane boosters used probably did increase the energy content of the fuel but pretty sure that has not been the case for years.

Now ethanol is commonly used to increase octane. Ethanol has fewer BTUs/gallon than gasoline so power will be reduced.

 

[NYC570]

This is interesting. I haven't tuned any of the recent Toyota/Lexus and their control strategy seems to now give more readouts, including this KCLV (Knock Correction Learn Value). Any idea how to get at it and if it's a PID that can be read in OBD-II? Or is there a proprietary software that can read this out on the IS-F? Perhaps on other Toyota's?

Until recently for the isf the only way to check the KCLV value used to be techstream. Now you can buy a bluetooth ODB-II reader and the OBD FUSION app along with the toyota PIDs from the app. This is how I check my isf. I haven't tried it out on the the lx.

 

[swatski]

...you don’t need the inputs to tell you anything about the resulting ignition advance, you just need the max degrees before TDC - a single output - for a given protocol from an LC running 87 and an LX running 91. If, over the course of a similar 50-mile protocol, the LX shows a higher degrees before TDC, it’s running more aggressive spark advance. At that point, you’ve proven your hypothesis that the LX is tuned for higher octane gas. Then it would also be interesting to see what the LC does on 91.

That is basically what the DAP site claims (I have no affiliation, and zero first hand knowledge and/or experience with them). I do not know enough to critically evaluate those claims, but I do find those to be (at last somewhat) believable:
From their site: FAQs | D.A.P. Tuning

Personally, the "hill test" as I described above has been the most convincing argument for me thus far, it is real.
But of course we are talking about pretty subtle difference here as far as measurable power outputs.

Is it worth it? It depends. So far I like my new Landy so much, I want to hear that engine running as perfect as it gets.

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[bjorn240]

That is an interesting data point; looks like they’ve done the work of looking at the retardation. Thanks!