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HighlanderGeneral discussion forum for the Toyota Highlander and Highlander Hybrid.
This is a discussion thread titled "Follow Up #1 Low Gas Mileage 2006 Highlander", within the Highlander forum, part of the SUV Forums category.
From my last thread I said I was getting 12 MPG on my AWD 6cyl Highlander. The dealer told me to switch from 93 octane gas to 89 octane gas. So I filled up a week ago with half 93 in the tank and added 89 octane. Today upon filling up with 89 octane I had gained miles. I went from 12mpg to 15mpg! Nothing else was changed. Now with probably all 89 octane in the tank I will track mileage/performance and get back to you all next week. I noticed so far no difference in performance/power.
Actually this goes AGAINST the grain here. Higher Octane always equates to Better MPG. It's the rule. The 3.3 VVT-i does say premium not required. But I noticed the hybrid version does say Premium required. The hybrid version is "tweaked"(programmed) differently though.
If yu went to three different dealers, I bet there would be 3 differing suggestions or explainations.
But, let us know of your results. I too get 12 mpg(Tank) with average local driving. I tried ALL grades and different brands of fuel. I feel Ammoco was consistently the cleanest burn and best MPG in general.. (not by much though) And I use a Scan Guage Onboard (OBDII scanner)to confirm my MPG readings against the On board trip Computer.
This poor MPG does elude me I have always felt, all things being constant, that the problem lies with inefficient Shift patterns in the transmission.
LT
This is my experience.
I have a 04 Limited with 3.3 with 70K on it. I have checked the MPG on the computer with my calc and it is normally +- 1 MPG.
If I fill up and get on the interstate and drive 300 miles @ 70 to 80 MPH I will get around 24 MPG on 93 Octane and add 1.5 to 2 MPG for 97 octane.
If I Fill up on Sunday evening and take my son to school and drive to work and back.~(45 mi interstate and 15 miles city) I will get 22MPG on 93 and add 1MPG for 97.
If I fill up and do 90% city it is around 17 MPG no mater what gas I use.
Note these are for "winter blend" gas Summer blend reduce this by 2 MPG.
I have had the transmission flashed and it did help the shifting but not the MPG. My AC is normally always on.
Things I have noticed....
>80 MPH KILLS the MPG
How you start off has the most influence on your MPG by far. Be easy on the gas when to start.
Have you tried resetting your ECU to let it re-create all the maps again?
That was the first thing dealers and other toyota techs said to do.
There is rarely a change observed. If there was ,eventually the changes revert back to the original state....poor MPG, lousy shift patterns.
This was observed with Toyota released firmware ECM flashes in a released TSB.
I've done the reset numerous times using different procedures and between using different grades of fuel.. Some have stated changing to a synthetic Trans. fluid corrected the "Shift gear hunting" problem.
I can't back that up as being true though. Toyota would have looked into this. No Dealer has felt this to be true fix. TIS would have directed them to do this.
This dilemma eludes all ,even Toyota. I say it is a combination of flaws in more than one area.
The dealer had said at the time, that the octane may have been too 'rich' and sometimes more is not better. I have of course never heard that before but what the heck, I had nothing to lose. I do little hwy driving, when I drove to VA last May I did get 24mpg on the highway using 93 octane. Presently I have 5k miles and have the car nearly 13 months. Other than the tires (Toyo, which are horrible) no problems. Like I have said earlier, my wife has the 2002 V6 FWD, and she drives at least twice as many miles as I do. She consistently gets 20 to 21mpg on 93 octane, loves AC/defroster. That car has 38k
The laymans procedure would be to just Disconnect the battery for five or more minutes. That will of course reset other setup items like your favorite radio stations etc More if yu have Nav. That would be the simplest way.
Yu can also hunt for the ECM relays or the Mains. But not necessary.
Aside from the actual Dealer Reflash(software update) of the Eeprom of the ECM this reset merely restarts the learning program. Driving habits, pedal activity, acceleration habits. But after several weeks or depending on usage/ mileage it usaully has calibrated back to where it used to be.
But, many people try it. Some dealers have done this as a first try quick fix. But there is no TSB specifying this procedure as a solution!
If every H/L owner with these same complaints drove to all the their respective dealers across the US and dropped of their cars by the hundreds if not thousands while under warranty, the dealers would scream at TMS and TIS for a fix. Dealers would be inundated . It would make the Automotive press like wildfire... But I bet things would be resolved somehow.
That was the first thing dealers and other toyota techs said to do.
There is rarely a change observed. If there was ,eventually the changes revert back to the original state....poor MPG, lousy shift patterns.
This was observed with Toyota released firmware ECM flashes in a released TSB.
I've done the reset numerous times using different procedures and between using different grades of fuel.. Some have stated changing to a synthetic Trans. fluid corrected the "Shift gear hunting" problem.
I can't back that up as being true though. Toyota would have looked into this. No Dealer has felt this to be true fix. TIS would have directed them to do this.
This dilemma eludes all ,even Toyota. I say it is a combination of flaws in more than one area.
LT
I would not state that it a change is rarely observed. I've performed this on all of our toyota vehicles with obdII, HL, is300, es330, rx350, etc... with expected results.
The key thing here is to drive normally or which ever style you want afterwards, it takes ~500 mi. to learn your driving patterns.
Some people have had success, some people haven't.
I would not state that it a change is rarely observed. I've performed this on all of our toyota vehicles with obdII, HL, is300, es330, rx350, etc... with expected results.
The key thing here is to drive normally or which ever style you want afterwards, it takes ~500 mi. to learn your driving patterns.
Some people have had success, some people haven't.
Which Scanner are yu using ? Do have Toyota specific software running on this Scanner?
LT
Which Scanner are yu using ? Do have Toyota specific software running on this Scanner?
LT
I'm not using any type of scanner. I just remove the negative, press on the brakes until my rear brake lights dim down. Put the negative back and document my travel habits for about 3 fill ups, 900-950 miles. In comparison to the "baseline" or documentation of the data before resetting the ECU.
Fill up #2 with 89 octane
I traveled 163 miles ( a bit more than usual, and some additional hwy driving) and I got 18mpg. By the way, I have been using the same Amoco gas station for 20 years...
Follow Up #1 Low Gas Mileage 2006 Highlander
Some have stated changing to a synthetic Trans. fluid corrected the "Shift gear hunting" problem.