Last post on Sep 05, 2007 at 12:13 PM
You are in the Toyota Highlander
What is this discussion about?
Toyota Highlander, SUV
#3 of 5 Re: HL Mileage and Octane Rating [mtairyordge]
Feb 19, 2007 (7:39 am)
The RON of 91 is the equivalent of 87 at the US pumps.
Higher octane as well as computer controlled ignition timing keeps the gas from igniting at the wrong time in a higher compression ratio engine. Engines with compression ratio's above 10:1 enter into that range.
The Highlander's 3MZ-FE engine has a ratio of 10.8:1. The computer can adjust for the use of 87. If you want "increased" performance, use 91 or higher as the user manual suggest for such.
#4 of 5 Re: HL Mileage and Octane Rating [nomorebenz]
Aug 12, 2007 (8:37 am)
"computer controlled ignition timing..." is no longer the primary resource for tuning the engien for differing octane ratings, not since the days of carburation anyway.
EFI, Electronic Fuel Injection, is now the primary "adjusting, adjustable" resource for the computer to use to prevent engine knock.
#5 of 5 no....
Sep 05, 2007 (12:13 pm)
timing is modified using the knock sensors to adjust the timing of the SPARK to accomodate lower octane fuels.
EFI just regulates the AMOUNT (and in some cases the timing of) the FUEL; the Electronic ignition controls the amount and timing of the SPARK, which is how knock/low octane fuel is addressed.
EFI won't address low octane fuel.