Fuel discussions/questions - Octane Regular or Premium (merged threads)
09-01-10, 07:53 PM
#16
Here it is a link from some law firm investigating the issue and looking for people who suffer injuries due to this problem
You have to love ambulance chasershttp://www.utahjusticelaw.com/lexus-...e-failure.html
09-02-10, 10:38 AM
#19
6th Gear
Join Date: Mar 2010
Location: AZ
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VIN is in 5K range. When I was traveling in states where Premium was 93 octane, I did not observe the problem. In states like AZ and CA where premium (regardless of brand) is 91 octane the problem is very obvious in my vehicle.
The problem occurs when accelerating from both a standstill and when accelerating at any speed.
Frank
2009 LX
2010 GX Premium
The problem occurs when accelerating from both a standstill and when accelerating at any speed.
Frank
2009 LX
2010 GX Premium
09-02-10, 05:12 PM
#21
Nor in sea-level Delaware using Valero 93 octane, but will report if we notice the problem.
If anything, the GX 460 is too aggressive ... unless we 'feather' the accelerator from a standstill or a slow speed ... it jumps! Impressive and reassuring, but a bit alarming to the passenger.
I've appended the fuel specification from page 752 of the 2010 GX 460 Owners Manual ... premium fuel only, i.e., a minimum of 91 octane. However, on page 762 we are told that "in a pinch" we may use lower than 91 octane, but that may result in engine knocking. Further, persistent knocking may lead to engine damage ... other than that, how did you enjoy the play, Mrs. Lincoln? ;-)
Regards,
SaniDel
If anything, the GX 460 is too aggressive ... unless we 'feather' the accelerator from a standstill or a slow speed ... it jumps! Impressive and reassuring, but a bit alarming to the passenger.
I've appended the fuel specification from page 752 of the 2010 GX 460 Owners Manual ... premium fuel only, i.e., a minimum of 91 octane. However, on page 762 we are told that "in a pinch" we may use lower than 91 octane, but that may result in engine knocking. Further, persistent knocking may lead to engine damage ... other than that, how did you enjoy the play, Mrs. Lincoln? ;-)
Regards,
SaniDel
09-10-10, 11:10 AM
#22
it takes quite a bit of abuse to have the engine knock from low octane gasoline. I'm talking going steep uphill, pulling heavy load, consistent WOT (wide open throttle) and so forth. If you're a mellow driver, even a lower octane will suffice (even though i personally wouldn't). I don't think your hesitation is from fuel grade.
09-10-10, 11:23 AM
#23
Lexus is investigating the hesitation issue. In the vibration thread (my issue), the dealer has mentioned that they have a rep coming to investige the hesitation and want to show my vibration issue. Personally I have not noticed the issue while going light and when towing 2500 lbs.
Last edited by Luke27617; 09-10-10 at 02:20 PM.
09-10-10, 12:40 PM
#24
We've been trying to duplicate the problem, but haven't seen it. We've tried some of what 'cannysage' suggests on a long, steep hill on a nearby highway. It is steep enough that the GX 460 can't hold speed on the upgrade without going out of ECO mode and downshifting. We've also tried 'sprinting' up the same hill holding the pedal to the floor ... lot's of fun, but no knocking.
What we can't duplicate is pulling a heavy load as we have no trailer hitch, much less anything to trail. The closest we got was on a recent road trip with three adults and a full load of luggage, but that's hardly the same as pulling a trailer.
Most of the time we would qualify as "mellow drivers" but those few times when we have to "stand on it" to avoid a problem would NOT be good times for the GX 460 to hesitate!
Regards,
SaniDel
What we can't duplicate is pulling a heavy load as we have no trailer hitch, much less anything to trail. The closest we got was on a recent road trip with three adults and a full load of luggage, but that's hardly the same as pulling a trailer.
Most of the time we would qualify as "mellow drivers" but those few times when we have to "stand on it" to avoid a problem would NOT be good times for the GX 460 to hesitate!
Regards,
SaniDel
09-16-10, 11:43 AM
#26
Conversely, in western states, which are at higher altitude, lower-octane gasoline is the norm. As altitude increases, air pressure decreases, which has a deleterious effect on engine efficiency, which can be offset to some degree by increasing octane, but only if it is available!
Regards,
SaniDel
09-25-10, 05:35 AM
#28
That may explain why we haven't seen any evidence of this problem. Here in sea-level Delaware 93 octane gasoline is readily available at most service stations and Sunoco sells even higher octane at some of their service stations.
Conversely, in western states, which are at higher altitude, lower-octane gasoline is the norm. As altitude increases, air pressure decreases, which has a deleterious effect on engine efficiency, which can be offset to some degree by increasing octane, but only if it is available!
Regards,
SaniDel
Conversely, in western states, which are at higher altitude, lower-octane gasoline is the norm. As altitude increases, air pressure decreases, which has a deleterious effect on engine efficiency, which can be offset to some degree by increasing octane, but only if it is available!
Regards,
SaniDel
Koz
09-25-10, 05:49 AM
#29
There is no need to use higher octane fuel at high altitude to compensate for the lower octane in the fuel in that area. At altitude, lower absolute pressure in the cylinder creates less heat when it's compressed, that's why the lower octane fuel will work fine. The only time you would want to use higher octane is if you are experiencing knock/ping. You will loss approx 3% HP for every 1K ft. and using higher octane will not create more power, you will only be wasting your money.
Koz
Koz
Thanks for the explanation. The relationship between altitude, octane and engine power is more complicated than I understood, but it makes sense and correlates to our experience.
On a long road trip in 1982 from sea-level Delaware to the Colorado Rockies the available octane dropped to as low as 85. Needless to say, our vehicle was sounding like a diesel at idle! I had to buy a set of cheap tools and manually retard the timing. The engine was barely making enough power to get us over some of those mountain passes and on one long uphill climb it gave up ... we coasted to the shoulder until we got it to restart.
Regards,
SaniDel
09-29-10, 05:42 PM
#30
Lexus Test Driver
Thanks for the explanation. The relationship between altitude, octane and engine power is more complicated than I understood, but it makes sense and correlates to our experience.
On a long road trip in 1982 from sea-level Delaware to the Colorado Rockies the available octane dropped to as low as 85. Needless to say, our vehicle was sounding like a diesel at idle! I had to buy a set of cheap tools and manually retard the timing. The engine was barely making enough power to get us over some of those mountain passes and on one long uphill climb it gave up ... we coasted to the shoulder until we got it to restart.
Regards,
SaniDel
On a long road trip in 1982 from sea-level Delaware to the Colorado Rockies the available octane dropped to as low as 85. Needless to say, our vehicle was sounding like a diesel at idle! I had to buy a set of cheap tools and manually retard the timing. The engine was barely making enough power to get us over some of those mountain passes and on one long uphill climb it gave up ... we coasted to the shoulder until we got it to restart.
Regards,
SaniDel