Quote:
Originally Posted by ElectroBoy
I re-read the first post and this question was asked: “How many today are using real gasoline if it can be found?”
If the OP really wanted to know, why wasn’t a poll included to count the responses?
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Giving the OP the benefit of the doubt, not everyone knows how to configure the poll or know the option even exists.
To answer your question earlier regarding 85 octane being sold in some states - it is due to the fact that because the DA is higher in these states, there is less oxygen to create a situation where the added octane would make a difference -- in theory. That was based on studies previous to modern day ECMs with dynamic timing though so take that with a grain of salt.
Although modern cars labeled with minimum 87 octane can run with 85, that doesn't mean there are no negative effects. If dynamic advance is a negative value, there is timing retard happening and, in layman's terms, not running at peak efficiency, raising EGTs, lower mpg and all the things associated with running lower than recommended minimum octane and timing. Because I don't have any tools available to datalog the 4Runner, this is just conjecture based on experience with the GT-R.
I keep referencing the GT-R because there is a plethora of tools and data available to reference. In 2013, Nissan released the car with a 93 octane minimum ECM map. For those who had access to 93 octane, it was the best performing factory variant GT-R released to date (in 2013) because the boost tables and timing maps were aggressively tuned... On 93 octane. For those who only had access to 91 octane, there were issues. Nissan later released a TSB to update the map so that it could tolerate 91 without excessive detonation and CELs. That's what would be rolled out to subsequent model years. The GT-R is still rated for 93 octane but it is still "fine" with 91 for certain parts of the year. However, there is very little margin of tolerance to account for high IATs, differing qualitiy of gas, etc. It easily goes into limp mode when the weather is above 60 degrees ambient which reduces timing, boost, and wastegate duty cycle but without a CEL. When that happens, it's easy to know when it occurs because boost goes from 14-15psi boost to 10 and throttle response is crap due to wastegate duty cycle going to 0 (running off of wastegate spring alone). You can also hear the difference. For those running 91 and don't want to tune the car to run at least E30 flex, we've been adding 2-3 gallons of E85 (at least 80% ethanol content) to boost octane which gets it close to the baseline recommended 93.
My point in the long winded explanation is that although we can run 85, there are consequences that we may not be consciously aware of in the 4runner. At the performance level of the 4runner, it isn't as sensitive and the effects not as obvious but I'll put a $1 on it and say that the computer is compensating in the background in one form or another when running 85 octane.
The agencies who control the blends of gas in these regions have been using antiquated data to claim it doesn't make a difference and some have said it comes down to the costs needed to make those changes at the refineries so we bear the costs if it affects the cars negatively. I have yet to talk to Magnuson or URD about the data they see in high DA states such as Colorado but I would be interested in hearing from tuners who have datalogged on the 4runner to see what they see in terms of how dynamic advance is affected.
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