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HighlanderGeneral discussion forum for the Toyota Highlander and Highlander Hybrid.
This is a discussion thread titled "Highlander Gas Mileage, Tips & Octane", within the Highlander forum, part of the SUV Forums category.
A short time back "Car & Drive" magazine ran dyno tests of several cars with different grades of gasoline. Their conclusion was that buying a lower, cheaper grade caused a break-even loss of power, so you needed more throttle to get the same power, burned slightly more gas, and didn't save any money. Buying higher octane resulted in a horsepower change that was too small for the dynomometer's instrumentation to read-out.
Originally posted by chawki12 What octain rating should I use with the V6. Has anyone checked gas milage using differant octain rating gas. What about performance.
Chawki12,
Running higher Octane in the Tundra will most likely have no benefit, unless your truck has been modified to ram more air into the cylinders...i.e. supercharger, higher compression ratio, etc. Gasolene is mostly heptane which combusts at a lower temperature than octane. This is because there is one less carbon bond to break. Engines that are modified with a supercharger for example run the risk of premature detonation (which causes pinging) and require a higher percentage of octane in their gas, due to the higher pressures in the cylinders.
If your truck is unmodified, then running higher octane will mean that you will be extracting LESS energy out of your gas than if you ran the lower octane. A common mis-perception is that high octane or 'grade' gas is cleaner than regular. This is purely a marketing ploy to get the average person to buy expensive gas. I was skeptical myself, so I did my own test. For three months I ran only 87, for three months 89 and finally exclusively 92 for three months. I kept track of my mileage and found that it was best with 87. I did this for my truck and for my Honda Civic. The results matched the theory (I'm a chemical engineer).
Unless your truck is modified, you are just throwing your money away buying higher grade gasolene. If you experience a constant ping then you just may be out of tune. When pulling a hill under load, your truck may ping occasionaly...this is normal.
For more information see the following:
Dr. Bill Wattenburg, who has a popular talk radio program on KGO 810 AM in the SF Bay Area, did a segment on this. To read, click the following link:
Several years back some brands of gasoline did have lower detergency in the cheaper octane levels. I do not think that's the case these days. I think that all quality gasolines have the full additive package in all their octane levels.
I'm just getting my wife's tomorrow, but the test you want to do is get a friend with a compatible Autotap program (or equivalent analyzer) and then do a couple of full throttle accelerations with the engine at operating temperature on your current gas while carefully logging the effect on Knock Retard. The engine computer will sense and back off the timing until the knock is eliminated.... at about 3 HP per degree of KR. And knock isn't good, even if the computer quickly eliminates it. Try the same thing with other octane levels and see what happens. If for example you see that you can eliminate knock with 89 Octane then you're probably going to be your best bang for the buck with that level of gas. You also need to consider the environment, and your driving habits. I tend to drive harder than my wife who would not usually ever be at WOT (wide open thottle) and she might never see knock at 87 Octane while I might get it at 91 Octane. Temperature is also a factor - cold air will help, hot air will hurt.
Our 2002 Highlander V6 is definitely peppier and more responsive on premium unleaded than on regular unleaded. Makes sense, too. The engine has a high 10.5:1 compression ratio, so it would not be able to run very much ignition timing advance on only 87 octane. With premium in the tank it would be able to run much more advance and therefore give a lot more power. Now we run nothing but premium unleaded.
Yeah, an OBD-II scanner set to track throttle position, ignition timing advance, and RPM would definitely be able to take a look at that.
My only question is how is the engine rated? Does it make...
Originally posted by SteVVT-i
Yeah, an OBD-II scanner set to track throttle position, ignition timing advance, and RPM would definitely be able to take a look at that.
The issue that I have with your findings is that manufacturers use the knock sensors as a stop-gap measure to prevent damage, not as a kludge for improper motronic mapping. They do not advance timing up until they sense a ping and then retard it back a degree. Once you have detonation in a cylinder you have to drop timing way back to stop it, so it is impractical to let the detonation start to begin with and would make for a very poor running engine.
Toyota builds most of their vehicles to run on 87 octane... including the Highlander. You might benefit from higher octanes in extreme conditions but without touching the ECU and revising the ignition curves there is little to be gained by running higher octane gas.
At least on the VQ30DE in my Maxima, igntion timing also varies with throttle position as well. You can see from the Excel plot where I was playing with the throttle a bit while revs remained steady (5th gear on highway) and timing went from 40 degrees BTDC to 20 or so depending on throttle opening.
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Originally posted by dpeete The issue that I have with your findings is that manufacturers use the knock sensors as a stop-gap measure to prevent damage, not as a kludge for improper motronic mapping. They do not advance timing up until they sense a ping and then retard it back a degree. Once you have detonation in a cylinder you have to drop timing way back to stop it, so it is impractical to let the detonation start to begin with and would make for a very poor running engine.
Not necessarily. It would be pretty easy to program in some "fast gain" and "slow gain" parameters for ignition timing advance based on what sort of gas is in the tank. Fast gain retard for when knock is actually detected, and slow gain control which could adjust the entire timing map based on the averaging of what sort of advance the engine can take before it starts detonating. Engine controls and electronics have come a very long way since the 90's, so I wouldn't be surprised if the ECUs have this sort of processing capability and programming in them.
The 98-99 Honda Odyessys were actually dual specified depending on what kind of gas was in the tank. 205 HP and 217 TQ on 87 octane, but 210 HP and 229 TQ on premium. The new Accord V6 (03+) also works the same way. The official company rating is 240HP/212TQ on 87 octane, but a Honda engineer interviewed in USA Today said that the engine was good for another 10HP/10TQ on premium. Track times from members at V6Performance.net have backed this up. 15.2 @ 91 on 87, but 15.0 @ 93 on premium under similar conditions and nearly identical 60' times. Dyno evidence has also backed this up, although only indirectly because nobody has done a direct back to back comparison of regular vs premium. Even the brochure for the 2002 Honda Pilot (240HP/242TQ on 87) stated that premium fuel was recommended for towing because the engine produces more torque.
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Originally posted by dpeete Toyota builds most of their vehicles to run on 87 octane... including the Highlander. You might benefit from higher octanes in extreme conditions but without touching the ECU and revising the ignition curves there is little to be gained by running higher octane gas.
If by saying "most" Toyota vehicles are designed for 87 octane, then you must be talking about the 4-cylinders. Because Toyota is recommending the use of premium fuel in every car that uses the 1MZ-FE 3.0L V6 engine. It's also recommended in the 2ZZ-FE Celica GT-S engine, and both the 4.0L V6 and the 4.7L V8 in the new 4-Runner (check for yourself). Toyota only recommends 87 octane for the 3.4L and 4.7L Tundra engines, though...
I inadvertently did an informal little test with our Highlander. It is my fiancee's primary car (I drive the Maxima), and I had taken it to work one day when she had a day off just for some seat time. We had been running 87 octane since the day we got it and it now had 5000 miles on it. On the way home I noticed it was near empty, so I stopped at the gas station and put some 93 in the tank. I drove it 2 miles back home and didn't notice any difference in performance immediately. The next day my fiancee took it to work (30 mile round trip through lots of DC traffic) and asked me when she got home...
"WHAT THE HELL DID YOU DO TO MY CAR?!?!?"
I got scared first, but then she said that the car felt a ton more responsive and like it had a bunch more power. Keep in mind that she wasn't with me when I filled up the tank, nor did I even tell her about it. I drove it later in the week (same tank) and I also noticed that it definitely seemed to have a lot more pep. We put a tank of 87 in it and noticed that the performance seemed to drop and mileage decreased also, so we went back to 93 and have stuck with it.
Because I didn't immediately notice the apparent power increase when I first put 93 in would also support my ignition advance "slow gain" vs "fast gain" ECU programming model also. But who knows.
I can definitely tell you from first hand experience though that the V-6 HL definitely feels more peppy and responsive on 93 than on 87, and my fiancee will back that up for ya too, and she doesn't know anything about cars. All she knows is what she feels. And Toyota recommends 91 "for best performance" right in the owner's manual, and it says it on their pressroom specs page also.
My only question is: how is the engine rated. 220hp/222tq on 87 or 91? I think it's probably 220/222 on 91, and that the engine actually makes somewhat less than that on 87. That would require some dyno time to confirm though, and our AWD HL is not a very good car to dyno. I'd love to see some results from a FWD HL, or any of the VVT-i 1MZ-FE engines, though.
Originally posted by SteVVT-i
At least on the VQ30DE in my Maxima, igntion timing also varies with throttle position as well.
Yep, I totally agree. My point is that I don't bother testing part-throttle maps - the WOT is all that I care about.
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It would be pretty easy to program in some "fast gain" and "slow gain" parameters for ignition timing advance based on what sort of gas is in the tank. Fast gain retard for when knock is actually detected, and slow gain control which could adjust the entire timing map based on the averaging of what sort of advance the engine can take before it starts detonating. Engine controls and electronics have come a very long way since the 90's, so I wouldn't be surprised if the ECUs have this sort of processing capability and programming in them.
Never seen that. The BMW stuff is on my '00 car which reacts very severely to ping. But clearly your later stuff validates this, so I learned something new. Thanks.
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If by saying "most" Toyota vehicles are designed for 87 octane, then you must be talking about the 4-cylinders...
My '01 Highlander owners manual just talks about 87. So when I said "most" it related to the non-performance engines (obviously the GTS-type models get fed the good stuff), but it looks like that has changed according to the internet resources. Curious what your owner's manual says to see if Toyota changed it?
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I inadvertently did an informal little test with our Highlander...
These types of anecdotal things normally mean nothing to me - I ignore them. But you have shown me that there is some additional ECU stuff I need to go play with. I can/will use the OBD-II tool to see what happens with advance with the highest/lowest octanes we have in Kalifornia (87/91). Thanks for the schooling.
Originally posted by dpeete Yep, I totally agree. My point is that I don't bother testing part-throttle maps - the WOT is all that I care about.
Yeah, there's a separate WOT map on the Maxima, and the HL also and probably most cars for that matter. You can see it in that chart I linked. Timing is 30-40 BTDC then drops to 15 or so and ramps up to 25 as I went WOT on the highway ramp.
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My '01 Highlander owners manual just talks about 87. So when I said "most" it related to the non-performance engines (obviously the GTS-type models get fed the good stuff), but it looks like that has changed according to the internet resources. Curious what your owner's manual says to see if Toyota changed it?
Paraphrasing our 2002 manual, it says...
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87 octane fuel is required. However, for "best performance" use of 91 octane fuel or higher is recommended.
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Originally posted by dpeete These types of anecdotal things normally mean nothing to me - I ignore them. But you have shown me that there is some additional ECU stuff I need to go play with. I can/will use the OBD-II tool to see what happens with advance with the highest/lowest octanes we have in Kalifornia (87/91). Thanks for the schooling.
Doug
np
I did a little bit of OBD-II telemetry recording on our Highlander but just never bothered to capture it into Excel yet like I did for my Maxima. But I'll post up results later when I get some time.
Just for reference (looking on my Palm PDA here in the lab), it was running 22-28 degrees of advance on WOT runs. That's with a 10.5:1 CR and 93 octane in the tank. That's more advance than my Maxima runs at WOT and it has a lower 10.0:1 CR. I don't think there's any way in hell the 1MZ-FE could run that much advance on only 87 octane fuel. If it does and was ping free I would be seriously surprised. And would also stop using premium gas.
Since you have an OBD-II scanner, definitely pull some telemetry for 87 vs 91 and lets compare notes.
It does take a toyota a pretty good while for the engine to set. I had the same problem with my tundra. It didnt really start to get good gas mileage untill I got to about 10,000 miles. You can bring it to a toyota service dept. They have a machine that can tell them exactly how many miles to the gallon that you are getting.
thanks for the reply...I also have a Tundra that i bought new in April. a 6cyl. 2wd automatic (reg cab). I put a camper shell on it, and get 18-19 mpg...currently 5000 miles on it.
I called Toyota National and they had a rep call my wife to set up a service appointment to check it out.
My 2003 Highlander V6 Limited 4WD is about 10 months old with just over 10,000 mile in it. I have never been satisfied with the gas mileage with my Highlander… although the manufacture suggested mileage is 18/23 for city/highway. I only can best it about 16/20 and 90% of time is worse than that. Who knows how Toyota rates its vehicles’ gas mileage… just not realistic to me at all.
Wow that doesn't seem right especially for a highlander..... I have a 2002 Tacoma Double cab and I average 19 mpg.... Which I a happy with considering it is a truck with large tires on it.... What octane of gas are you using? Are you doing more highway or city driving? My Solara that I have as well with the v6 gets about 26mpg..... and that is with 19" wheels on it......
Mark
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Originally Posted by memaster
My 2003 Highlander V6 Limited 4WD is about 10 months old with just over 10,000 mile in it. I have never been satisfied with the gas mileage with my Highlander… although the manufacture suggested mileage is 18/23 for city/highway. I only can best it about 16/20 and 90% of time is worse than that. Who knows how Toyota rates its vehicles’ gas mileage… just not realistic to me at all.
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