Octane, MPG and ECT PWR button - question
Octane, MPG and ECT PWR button - question
I know that Lexus requires 91 min octane. I've searched.
Background:
I have a 2007 IS350 Sport Package that is not modified (other than a JoeZ intake). I drive almost exactly 100 miles a day to and from SC to NC. Gas is a lot cheaper in SC so it's important to me to buy gas in SC and not NC. I do get over 400 miles per tank. I have a gas card for BP and there is only one BP near me so I always buy gas at the same station. I live near a lake and the BP offers 89 (100% gas). They also offer 93 and 87 both at 90% gas 10% ethanol. I drive relatively conservatively all of the time. I drive with the ECT PWR button on all of the time. I drive 1/3 on back roads (45mph posted) with stop lights, the other 2/3 is highway (65mph posted). I exceed the speed limit as much as a normal person would. The 89 cost as much or more than the 93, so cost was not the factor regarding this experiment. I tried it the first time just because the 89 was 100% gas with 0% ethanol. On the weekends, I drive another vehicle as not to skew the data.
I have done this "trial" over the past 5000 miles so traffic and slight variences in speed should have been averaged out.
Information on "experiment":
When running 93 (10% ethanol) I get between 27-28 mpg. Let's call that 27.5. When running 89 (100% gas) I get between 29-30. Let's call that 29.5. So, almost an increase of 10% mpg. I always fill my tank around 400 miles so IF I'm switching octane, most of the other gas is out of the tank. Utilizing the "Tank MPG" display, my mileage ALWAYS increases within the first 20-30 miles of driving on the new tank of 88, and ALWAYS decreases with the new tank of 93. Hence, I don't believe the ECU is "recalculating" anything. I've tried alternating octane every fill up. I've tried five fill ups on each before changing. The 89 cost as much as the 93 so there is nothing to be gained by utilizing one of the other.The only thing outside of normal operation I do is run the ECT PWR button on all the time, that is the reason I mention it.
Possible hypothesis:
1- I assume that because my mileage increases with 89 100% gas, my car must be operating more efficently. That may be a bad assumption as I know Lexus "requires" 91 octane min.
2- I think (and cannot prove) MAYBE that the ECT button increases timing and this is what is effecting my mileage????
3- Another possibility is that when the trucks come to fill up the station tanks, they "top off" the 93 with 87 at the direction of the station owner. Yes, I know that would be unethical. I also know that it's more profitable to sell 87 at 93 prices and it does happen. I don't know whether or not it happens at that BP. I do know if that happens then the 93 is no longer 93, it has to be something less....Since the 89 100% gas is a "new feature" at that station, I don't think that has happened... at least yet.
Question:
Ultimately, I'm hoping someone can explain this phenomenon.
Background:
I have a 2007 IS350 Sport Package that is not modified (other than a JoeZ intake). I drive almost exactly 100 miles a day to and from SC to NC. Gas is a lot cheaper in SC so it's important to me to buy gas in SC and not NC. I do get over 400 miles per tank. I have a gas card for BP and there is only one BP near me so I always buy gas at the same station. I live near a lake and the BP offers 89 (100% gas). They also offer 93 and 87 both at 90% gas 10% ethanol. I drive relatively conservatively all of the time. I drive with the ECT PWR button on all of the time. I drive 1/3 on back roads (45mph posted) with stop lights, the other 2/3 is highway (65mph posted). I exceed the speed limit as much as a normal person would. The 89 cost as much or more than the 93, so cost was not the factor regarding this experiment. I tried it the first time just because the 89 was 100% gas with 0% ethanol. On the weekends, I drive another vehicle as not to skew the data.
I have done this "trial" over the past 5000 miles so traffic and slight variences in speed should have been averaged out.
Information on "experiment":
When running 93 (10% ethanol) I get between 27-28 mpg. Let's call that 27.5. When running 89 (100% gas) I get between 29-30. Let's call that 29.5. So, almost an increase of 10% mpg. I always fill my tank around 400 miles so IF I'm switching octane, most of the other gas is out of the tank. Utilizing the "Tank MPG" display, my mileage ALWAYS increases within the first 20-30 miles of driving on the new tank of 88, and ALWAYS decreases with the new tank of 93. Hence, I don't believe the ECU is "recalculating" anything. I've tried alternating octane every fill up. I've tried five fill ups on each before changing. The 89 cost as much as the 93 so there is nothing to be gained by utilizing one of the other.The only thing outside of normal operation I do is run the ECT PWR button on all the time, that is the reason I mention it.
Possible hypothesis:
1- I assume that because my mileage increases with 89 100% gas, my car must be operating more efficently. That may be a bad assumption as I know Lexus "requires" 91 octane min.
2- I think (and cannot prove) MAYBE that the ECT button increases timing and this is what is effecting my mileage????
3- Another possibility is that when the trucks come to fill up the station tanks, they "top off" the 93 with 87 at the direction of the station owner. Yes, I know that would be unethical. I also know that it's more profitable to sell 87 at 93 prices and it does happen. I don't know whether or not it happens at that BP. I do know if that happens then the 93 is no longer 93, it has to be something less....Since the 89 100% gas is a "new feature" at that station, I don't think that has happened... at least yet.
Question:
Ultimately, I'm hoping someone can explain this phenomenon.
Intermediate
Joined: Oct 2012
Posts: 460
Likes: 7
From: Kailua, HI
Ethanol is garbage and lowers the efficiency and mpg of your engine. Even though you're running a few more octane points, you're now introducing 10% filler material into your gas with the 93 vs pure gas with the 89.
The whole ethanol thing was perpetrated by corn farming lobbyists to help drive up the prices since a new found demand would be created. In reality, it's about as **** poor of a gasoline filler as you could find. Mandating ethanol into our gas supply to help "save" gas is BS.. because now we've just lowered the efficiency of vehicles all over the country.. thereby INCREASING the demand for gas. The EPA knows it but there's huge money involved to keep it that way.
Mystery solved.
The whole ethanol thing was perpetrated by corn farming lobbyists to help drive up the prices since a new found demand would be created. In reality, it's about as **** poor of a gasoline filler as you could find. Mandating ethanol into our gas supply to help "save" gas is BS.. because now we've just lowered the efficiency of vehicles all over the country.. thereby INCREASING the demand for gas. The EPA knows it but there's huge money involved to keep it that way.
Mystery solved.
Last edited by jsmacks; Nov 8, 2012 at 05:31 AM.
Ethanol contains 34% less energy per unit of volume than gasoline, so you will always get worse mileage with something containing ethanol.
It's sort of weird they do a 90/10 mix for 87 and 93 but NOT their 89... but it's possible that also means they're offering a winter blend in one but not the other, which would also impact mileage.
Most likely, especially since that's pretty flat roads you're on, and not towing or racing anyone, you're simply not pushing the engine hard enough to run into timing retard with the 89, and are seeing the mileage difference in fuel blends you'd expect.... but you'd need to hook up an OBD2 monitor and log timing events to know for sure.
AFAIK nobody has ever shown any evidence ECT mode on the 2iS, inherently, does anything to engine timing.
It's sort of weird they do a 90/10 mix for 87 and 93 but NOT their 89... but it's possible that also means they're offering a winter blend in one but not the other, which would also impact mileage.
Most likely, especially since that's pretty flat roads you're on, and not towing or racing anyone, you're simply not pushing the engine hard enough to run into timing retard with the 89, and are seeing the mileage difference in fuel blends you'd expect.... but you'd need to hook up an OBD2 monitor and log timing events to know for sure.
AFAIK nobody has ever shown any evidence ECT mode on the 2iS, inherently, does anything to engine timing.
Ethanol contains 34% less energy per unit of volume than gasoline, so you will always get worse mileage with something containing ethanol.
It's sort of weird they do a 90/10 mix for 87 and 93 but NOT their 89... but it's possible that also means they're offering a winter blend in one but not the other, which would also impact mileage.
Most likely, especially since that's pretty flat roads you're on, and not towing or racing anyone, you're simply not pushing the engine hard enough to run into timing retard with the 89, and are seeing the mileage difference in fuel blends you'd expect.... but you'd need to hook up an OBD2 monitor and log timing events to know for sure.
AFAIK nobody has ever shown any evidence ECT mode on the 2iS, inherently, does anything to engine timing.
It's sort of weird they do a 90/10 mix for 87 and 93 but NOT their 89... but it's possible that also means they're offering a winter blend in one but not the other, which would also impact mileage.
Most likely, especially since that's pretty flat roads you're on, and not towing or racing anyone, you're simply not pushing the engine hard enough to run into timing retard with the 89, and are seeing the mileage difference in fuel blends you'd expect.... but you'd need to hook up an OBD2 monitor and log timing events to know for sure.
AFAIK nobody has ever shown any evidence ECT mode on the 2iS, inherently, does anything to engine timing.
I do have a scan gauge semi-permantly mounted in my Landcruiser. I could check the timing myself, good idea.
Moronic isn't it...
Lexus Test Driver
Joined: Apr 2008
Posts: 1,363
Likes: 2
From: Ontario
Ethanol contains 34% less energy per unit of volume than gasoline, so you will always get worse mileage with something containing ethanol.
It's sort of weird they do a 90/10 mix for 87 and 93 but NOT their 89... but it's possible that also means they're offering a winter blend in one but not the other, which would also impact mileage.
Most likely, especially since that's pretty flat roads you're on, and not towing or racing anyone, you're simply not pushing the engine hard enough to run into timing retard with the 89, and are seeing the mileage difference in fuel blends you'd expect.... but you'd need to hook up an OBD2 monitor and log timing events to know for sure.
AFAIK nobody has ever shown any evidence ECT mode on the 2iS, inherently, does anything to engine timing.
It's sort of weird they do a 90/10 mix for 87 and 93 but NOT their 89... but it's possible that also means they're offering a winter blend in one but not the other, which would also impact mileage.
Most likely, especially since that's pretty flat roads you're on, and not towing or racing anyone, you're simply not pushing the engine hard enough to run into timing retard with the 89, and are seeing the mileage difference in fuel blends you'd expect.... but you'd need to hook up an OBD2 monitor and log timing events to know for sure.
AFAIK nobody has ever shown any evidence ECT mode on the 2iS, inherently, does anything to engine timing.
Here in Canada, most oil companies sell Premium being 91Octane and no ethanol, mid-grade being 89 octane with "up to" 5% ethanol and regular being 87 Octane with "up to" 10% ethanol. Since the gas is being sold as "graded gas" not just based on octane level the price differencial between regular and premium is almost 16 cents a liter (or about 60 cents a US gallon),
Lexus Champion
Joined: Jan 2006
Posts: 3,763
Likes: 6
From: TX
The way i have observed the is250 engine work (how it feels, in short) in ECT PWR mode, it is very similar to the way any gasoline engine would feel if you retarded timing, and vice versa for advance timing.
I wish somebody who has the tools can corroborate this for us.
I wish somebody who has the tools can corroborate this for us.
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I know Gernby did some extensive datalogging back in the day, he's where we first discovered ECT-PWR shifts lower than normal mode at WOT, and I don't recall him ever noticing any timing difference in ECT modes.
Driver School Candidate
Joined: Sep 2012
Posts: 3
Likes: 0
From: SC
They picked 89 because some cars require premium, most call for regular and since I'm near a lake they wanted to offer a ethanol free for boats and 89 wasn't a big seller....sooo.... AND all of this was done in the summer. Hopefully, we are just starting to get winter gas here.
I do have a scan gauge semi-permantly mounted in my Landcruiser. I could check the timing myself, good idea.
I do have a scan gauge semi-permantly mounted in my Landcruiser. I could check the timing myself, good idea.
on a positive note, where i am, gas has dropped under $3/gallon. Of course, for me this isn't the case as I never fill below 91 rating, but it is still making it cheaper.
Its actually kind of disturbing to think that any gas station would put 87 in their 93/91 tanks...what if a person filled up at the same station for years and they have been filling 87 thinking they were getting 91/93 and the engine starts knocking over time and some.engine issues come up, is there a lawsuit in that if it can be proven? Just curious, its a pretty scary scenario now that I think about it =X
Last edited by Phresh2010; Nov 9, 2012 at 07:29 AM.
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