IPutting high octane in an engine that doesn't use the knock sensor in the first place is a waste. Now if its retarding the timing, then yeah, higher octane will help.
There was another poster who told me (about two months ago) that the insight retards ignition timing frequently.
__________________
OWN: 61mpg Insight (greenercars.org score: 57)
both blue and silver,
and a 45mpg BeetleTDI (score: 47).
Install a scan tool or an OBDIIC&C gauge and you will be amazed and shocked at what it does.
__________________
01 MT "Little Red Rocket"
The first "TURBOCHARGED" Hybrid, Insight G1- (01/2003)
MaxIMA Battery (Serial #2), on 8/25/12 @ 301,520 miles
Use: 320,000 mi. @ 57.8 LMPG
what ive found is the ecm is slow to learn (really, all obd2 units are). Point being running one tank may not be enough time for the ecm to understand it "can" raise the ignition advance. Granted, there is only so much advance programed into the ecm, and that varies auto maker to auto maker. In multiple tests ive done in the I1, 93 (thats what we have here) always improved mpg and (some) power. Where i did notice a constant change was in the voltages of the primary o2 readings. Running 87 oct, voltage stays around .5-1.0 volts. Lean burn nets .355-.450 volts. In contrast, 93 nets readings of .250-.385 in lean burn-that translates to better mpgs
I red somewhere in the owner manual that the I1 should use 91 octane,//
I recall seeing this as well. I think I saw it in my own owners manual in the my Cdn car, although the owners manual uploaded here pg. 118 says only 87 AKI octane or greater.
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[Edit: had a look in daylight at my Cdn Owners Manual in the car and it said as above. Wondering where I saw that now.?
There was an old post by 'Rick' in this early 2003 thread "Does Premium or Brand Gas Matter?" linked here: Does Premium or Brand Gas Matter? which may be worth a read.
Also Check out 'Point 4' linked here "Why is ethanol an effective octane booster?"
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The linked google.doc .pdf copy of the manual notes that for some Canadian gasolines, because of the possible MMT octane booster in fuel formulations, harm could occur to the emissions control system. [catalytic converter gets sludged up with Magnesium]
Possibly premium gas was recommended initially because of the higher amount of detergents for a cleaner burn in the super blend vs. the regular.
MMT isn't used in Canada anymore as far as I know so no worries.
Where i did notice a constant change was in the voltages of the primary o2 readings. Running 87 oct, voltage stays around .5-1.0 volts. Lean burn nets .355-.450 volts. In contrast, 93 nets readings of .250-.385 in lean burn-that translates to better mpgs
About what mileage increase did you see? Have you translated those lean burn A/F volts to A/F ratios?
On the i2 it seems to advance the timing 1 degree til it senses a knock then retards it 3 degrees. I can pull the ground strap when I fill up with high octane and see what happens. I think I found with the scion or the toy vvt that helped with any changes and from time to time for supreme mpg.
"About what mileage increase did you see? Have you translated those lean burn A/F volts to A/F ratios"
Ive noticed around 10mpg increase on long commutes/hwy driving. the avg though is about 50 or so more miles to the tank. I trust the avg because that route is the exact same each day-even with all the other factors i cant recreate (traffic, wind, temp) i still gain an extra trip a week with 93 vs 87.
I havnt translated the volts to AF ratios-At this time, i only know that the lower the volts, the higher( lean) the AF is. If i had to guess though-.5 should be 14.7 to 1. When time permits i may try to test it with a "sniffer" to verify that. Now, if someone knows for sure the highest AF ratio the car will do, then mathematically we could figure it out
Without knowing the secrets of the ECU programing, and based on some testing that I did while installing the turbo, it appears that max. AF is around 12.5-13.0, (with out use of the turbo.)
RPM is also another factor to figure in. The higher the rpm and timing, the richer the mixture.
It all points back to load, rpm, and ignition timing.
(From experience)
HTH
Willie
__________________
01 MT "Little Red Rocket"
The first "TURBOCHARGED" Hybrid, Insight G1- (01/2003)
MaxIMA Battery (Serial #2), on 8/25/12 @ 301,520 miles
Use: 320,000 mi. @ 57.8 LMPG
"About what mileage increase did you see? Have you translated those lean burn A/F volts to A/F ratios"
Ive noticed around 10mpg increase on long commutes/hwy driving. the avg though is about 50 or so more miles to the tank. I trust the avg because that route is the exact same each day-even with all the other factors i cant recreate (traffic, wind, temp) i still gain an extra trip a week with 93 vs 87.
I havnt translated the volts to AF ratios-At this time, i only know that the lower the volts, the higher( lean) the AF is.
On a normal W/B sensor the higher the voltage the leaner the mixture. Here's two links with curves etc.
If i had to guess though-.5 should be 14.7 to 1. When time permits i may try to test it with a "sniffer" to verify that. Now, if someone knows for sure the highest AF ratio the car will do, then mathematically we could figure it out
Unfortunately the voltage/Lambda curves aren't linear.
2.5 volts is a typical reading for wide band sensors at 14.7:1. But since the Insight can run so much leaner than other cars, Honda may have special sensors in it.
I measured my CRX with a 1954 Sun fuel/air ratio meter (which correlates reasonably close to a normal wide band sensor setup) and found that my CRX rarely runs at 14:1. It ran at ~17:1 when cruising along at 30-40 mph. The only way I could get it to drop to 14:1 was by giving it some throttle.
Once I get my Insight on the road I'll test it with the Sun meter. Here's what it looks like. The small pcb unit is a modern equivalent to the Sun.
Somewhere on the web I read an Australian car review done years ago on a G1 Insight and I seem to remember that the max the car was running on lean burn was 28:1!! It took awhile to get there but it did it. Apparently 24:1+ wasn't too hard to get. I just looked again and naturally I can't find the article now.
Occasionally I ran 87 Octane in the 2000 base Corvette I had until June this year. The first time I put 87 in was from not paying attention, but I would do it occasionally after that. Believe the CR was 10.5:1. The computer simply adjusts the timing on start up. It actually had better low end torque with the 87 Octane, and I saw no difference in fuel mileage, which averaged 24mpg for me.
If we had ethanol free gas around here I would use it, as that 10 percent of alcohol in the mix has only half the heat energy of gasoline.
My 0.02 worth,
Tim Glover
Last edited by TopFuelTim; 01-11-2013 at 06:45 AM.
Reason: can't spell
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