Turbo, Fuel Octane and Altitude

Where are you getting E10 97 and 99 octane fuel?

As for ping, I've had opportunity to test this, but I suppose there is lower limit to ignition retardation--your 2004 would have had knock sensors-- that would make pinging pronounced; e.g the PCM detects the knock from the knock sensor, but can't make further timing retard, and thus only highly octane fuel would solve.
My bad. That was supposed to be E10 87 and 89. That post has been corrected.
 
Think I should just fill up with Costco Premium along the way and not give it a second thought.
That might require some planning. Costco has only about 600 stores in the US, fewer than the number of Tesla charging stations. See the the following map and store database:


Even if you go by a city that has one you might still have to go quite a ways off your desired route.
 
I noticed that the increase in fuel economy when switching from regular ethanol-blend to premium ethanol free entirely offset the price difference. The ECU on my NA Mazda 6 is not even designed to run on premium. Since then, the car has been fully tuned for 91 and I fill up almost exclusively at an independently owned franchise that still happens to use an ethanol-free blend for their premium. I did it primarily due to a significant subjective improvement in smoothness during low RPM operation.

BTW, the engine should be able to detect knock and adjust timing essentially as soon as it happens. All it would take is about 1L of consumption of whatever is in the fuel lines for the new fuel to begin passing through.

My personal take, if you are detecting a lack of refinement at the lower RPM's, or have some tuning software which indicates that your engine is detecting knock and pulling back timing,

1. Source ethanol-free fuel
2. Try adding some octane booster and/or fuel system cleaner (Which will typically have some octane booster blended in as well)

Otherwise, I don't think I would splurge for premium gas if it was also ethanol blended. During my testing, I only noticed a difference with ethanol-free.


If anyone would like to take a look at some of the datalogging I have gathered during the tuning process for my NA 2.5, don't hesitate to reach out.
 
Power loss is 3% per 1000 feet of elevation increase.
To some elevation, the turbo may be able to hold off the loss.
 
Power loss is 3% per 1000 feet of elevation increase.
To some elevation, the turbo may be able to hold off the loss.
I can feel my turbo (2023) cx5 losing giddy up at elevation over 6000 feet or so even with 91 octane.. I spend the last couple days up around 6000-7000 feet and definitely felt more anemic when flooring it to get around slow moving vehicles...I live at 3300 feet or so and don't notice much of a difference when going down to sea level but always do when going up over 6000 feet or so.
 
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