Premium vs Regular - 93 or 87 Octane - For Your Tow Vehicle (Toyota Trucks?)

[swatski]

DISCLAIMER: I have too much going on in my work and in my life.
So, naturally... I seek time-wasting distractions such as internet forums, 87 vs. 93 octane, and reading about superchargers. ( yes, those are the real reasons for starting this thread; and yes, it is better than therapy, lol)


I started experimenting with low (87, regular) vs high (93, premium) octane after reading about new-er Toyota engines being controlled by sensors - almost entirely.

The way I understand it, Toyota has decided to allow the software (algorithms) to take raw data, in real time, to calibrate and run the ECUs so there is no actual "tune", more like running within a "constant variable" depending on readings from sensors - pre-drivetrain, post drivetrain, and everything in the middle...

One of the things I read that made an impression on me was the DAP tuners claim that "These engines pull 8-12 degrees of timing due to knock retard on 87 oct, 6-10 deg on 89oct, 2-6 deg on 91oct, and 0-2deg on 93oct. That is on a completely stock truck with factory tune." Wow! (if that's true).

Which poses some interesting questions, and makes some specific predictions.
Will it run perfectly fine and reliably on 87? Yes.
Will it run better on higher octane? Probably.


I decided to look into this some more. Over a period of time I ran my 2017 5.7 V8 Toyota switching half-tanks of either 87 or 93 gas (running on empty in between to minimize mixing the two grades).

Consistently, my engine was noticeably quieter running 93, under no/various loads. Most notably, the engine did not down shift as much compared to 87 gas - most apparent at highway speeds, but similar when driving a local route - going over the same hills and keeping the same speed.
(I didn't notice any better/changed MPGs.)

I also ran another Toyota truck, wife's 2016 4Runner 4.0 V6, on 93 vs regular octane and again seen more power and engine not down shifting as much with 93 as compared to 87 gas - driving the same route, same hills and speed.
(Again, no increase in MPG)


I conclude that with these trucks 93 octane provides for more power (through more timing?) under a given load.

That additional timing and resulting power would undoubtedly come in handy towing our boat - for example around Arkansas hills on trips to Bull Shoals Lake!

But - if 93 octane really gives me more power - I would run it all the time.

Thoughts?

--

 

[GiddYupJoe]

If premium is not reccomended but could give you a more positive driving experience... is that gain worth the price of admission at sometimes .75/1 more per gallon?

When your talking 38 gal tanks as I have on my Tundra, that is a steep premium! But if the difference was night vs day then maybe your on to something.

 

[Sbrown]

Thoughts?

A more objective way to test your theory may be to connect a scan tool that is capable of reading live data and just watch the knock sensor and timing retard readings.

 

[2kwik4u]

Have you done any datalogging yet? I would be curious to see what realtime timing advance numbers are being run.

The PID's to log would be:
Throttle %
Load %
Timing advance
RPM
Intake temp
ambient temp
coolant temp
injector pulse width
O2 millivolts

I've been doing the same tests in my 5.3 Sierra. Probably spurred by the same thread on here. It has a similar effect. The engine feels quieter and smoother overall. I also notice that it is spending more time in V4 mode over V8 mode. Typically on the highway when cruising. Overpasses and such aren't causing it to downshift or drop out of V4 mode. I haven't done any data logging yet to validate any higher power/efficiency numbers though.

Also, a note on tuning. All new cars/trucks have this closed loop feedback capability. They have for quite some time. In the Eraly 90's GM was using "cross counts" (The number of times the O2 voltage crossed .500) to determine if the engine was rich or lean and adjusted fueling with "long term fuel trims". So this premise isn't anything new or overly exciting. The big advancements in recent years have been on the speed in which the ECM's run, and the reliance on sensors to "trim" the particular parameters. So, there is still a base tune in the ECM. A starting point for the ECM to begin running the engine. This base map is just purposely set VERY aggressive, and then the sensors are left to give feedback to the ECM to adjust the tune BACKWARDS to where it's "safe". This methodology is paradigm shift that allows an engine to develop more power on premium fuel, or cooler/more dense air.

My '12 Focus was the first car I had that was setup with this methodology, and the first car that I had where running a higher octane made a difference. I tested that car over a 3 month period and found that it was cheapest to run it on 93 octane at about $0.115/mi. 87 octane was around $0.157/mi, and E85 was around $0.122/mi. The E85 ran the best, hands down, with the quietest and smoothest feeling of power, but had the worst mileage at around 26mpg (93 octane got me around 33mpg). The subsidized price of E85 made it work out closer on $/mi though.

Anywho, I'm hoping to start logging here soon. Maybe I'll take some time tonight and get my Torque Pro app setup to datalog the appropriate PID's and start doing some real testing.

OH......another thing. I use the ACAR app to log my fuel mileage. I use the notes section to keep track of several things including octane rating. HERE is my Fuelly.com page where all the data is backed up. It's an interesting look through and a great tool for tracking this sort of thing, as you can dump your results to a .csv file and really crunch the data if you like.

 

[swatski]

The engine feels quieter and smoother overall. I also notice that it is spending more time in V4 mode over V8 mode. Typically on the highway when cruising. Overpasses and such aren't causing it to downshift or drop out of V4 mode. I haven't done any data logging yet to validate any higher power/efficiency numbers though.

That sounds very familiar! (except V4 mode)

As far as logging, I'm feeling a bit reluctant trying to do it myself - in light of being fairly ignorant and what information is already available. If I understand correctly what you are saying about the base maps being maximally aggressive w/everything else left to sensors to pull back into a safe zone - that makes perfect sense to me!

--

 

[swatski]

If premium is not reccomended but could give you a more positive driving experience... is that gain worth the price of admission at sometimes .75/1 more per gallon?

When your talking 38 gal tanks as I have on my Tundra, that is a steep premium! But if the difference was night vs day then maybe your on to something.

That is very true! Those price differences are not trivial.

I'll say though, based on my very limited experience and what I hear here, so far, I would still use premium when towing the boat - if those explanations hold water and more octane = more power (under specific circumstances/within limits).
The few boat tows I have done with premium gas, no long ones yet, make me a believer...
(I'll also admit to being spoiled, and now nostalgic, my previous tow machine - a Q7 TDI - was an absolute beast for highway towing)

--

 

[geohil]

Sounds like we have similar garages - and here have been our findings over the last 40k:
Wife's '15 4Runner with the 4.0
With 87 octane (10% ethanol) MPG averages 16.7, bit rougher idle but have not noticed changes in shift patterns.
With 93 octane (10% ethanol) MPG averages 16.3, idle is noticeable smoother, same shift points
With 93 octane (non-ethanol) MPG averages 15.9, but the idle is butter and the truck doesn't need to up-shift as often. Power would be the only reason for the lack of up-shifting.

Now on the Tundra 5.7 ....I'm supercharged so premium is a must. 16.3 for ethanol, 16.5 for non-ethanol. Non-ethanol helps eliminate low RPM ping as the truck lugs as if I recall the knock sensors don't go active until 2500 rpm or so. I have DAP tuning on my shortlist, but that is more for getting rid of the active torque management. That feature that is in both your 4Runner and Tundra make it feel like the rig is hunting for gears constantly. From my understanding just nixing that feature helps power and MPG. With DAP tune I'll be around 550HP which really isn't needed....but so much fun.

So for your purposes when/if you get tuned it will be tuned for a higher octane fuel, but the big advantage is getting rid of the ATM. For your 4Runner look into SprintBooster. Gets rid of the ECM lag programmed into the drive by wire.

 

[swatski]

So for your purposes when/if you get tuned it will be tuned for a higher octane fuel, but the big advantage is getting rid of the ATM. For your 4Runner look into SprintBooster. Gets rid of the ECM lag programmed into the drive by wire.

No plan to get a tune, or supercharger, lol. I love when the truck holds the RPM as low as possible - and switching to 93/premium seems to have helped.
But doing something about the "ATM" would be wonderful! What makes me realize how much power is being lost due to this electronic control.

The torque management system is so crazy (mine is a Land Cruiser) how the engine and trans function when it's cold (not warmed up)... Press the throttle, and the engine revs up, but the truck barely moves...

Is there a way to eliminate that without reflashing/tuning? (ECT mode does not help with that)

--

 

[geohil]

No plan to get a tune, or supercharger, lol. I love when the truck holds the RPM as low as possible - and switching to 93/premium seems to have helped.
But doing something about the "ATM" would be wonderful! What makes me realize how much power is being lost due to this electronic control.

The torque management system is so crazy (mine is a Land Cruiser) how the engine and trans function when it's cold (not warmed up)... Press the throttle, and the engine revs up, but the truck barely moves...

Is there a way to eliminate that without reflashing/tuning? (ECT mode does not help with that)

--

I believe Bullydog tuners have the ability to shut it off, but I haven’t looked much into that as BD’s don’t tune well with S/C trucks.

The way they behave when cold is frustrating sometimes. Same with all the traction control nannies.

 

[seanmclean]

Personally, if the vehicle has adequate power for your day to day driving and towing, I'd just stick with 87. If you're planning a trip through a hilly area, switch to 93 for it. I'd be curious if it's just a placebo effect, though. Maybe have the wife fill up next time you're really low and not tell you which she put in.


Also, me personally, I'm not spending an extra thirty bucks a tank for a little extra power - but I'm a cheapass.

 

[djetok]

Not a Toyota but my new Lincoln with twin turbo 3.0 got 34.7 Mpg on 93 on my run from Austin to Edmond, ok last weekend. The 93 in Austin 3.20 per gallon so if I lived there I would always buy it . Here in the OKC area there is only 1 station that sells 93 and its non ethanol at 4.18 per gallon. I do that when I want to unleash the 410hp to wheels, its a lot fun. The cost difference is not worth it otherwise for me. I only have 110 miles of fun left , unless I want to spend 4.18 per gallon.

 

[WildBillF1]

I also have a 2017 Tundra with the 5.7 V8. I have looked into the DAP tune, but not pulled the trigger. I have run 87, 89 and 91 octane and honestly can't tell a difference in performance. Up until a few years ago I ran open track days with my motorcycles. I had a CBR929 and a CBR954, no mods to engine internals and they both turned faster times on the track using 87 octane, as recommended by Honda. I've learned to just run whatever the vehicle manufacturer suggests.

 

[swatski]

I'd be curious if it's just a placebo effect, though. Maybe have the wife fill up next time you're really low and not tell you which she put in.

lol, done that. Nothing extensive/scientifically/statistically significant, but the difference is easy to pick up/tangible.
@WildBillF1 I can't say there is a difference in actual (timed) performance under hard acceleration, top speed/quarter mile etc type of comparisons, the differences I observe most clearly are in shift points (holding gears longer before downshifting - which is great!) and pulling power at low RPMs (under 2,000) at highway speeds. Also, just general - engine running and idling smoother.

This does not apply to all engines, certainly not to our jet boats. I believe you are right about 87 being "faster" - same with the Yamies, I see no performance gains what-so-ever with 93 in my AR240 (running with factory tune), and @SamCF has tested that more extensively and his fastest runs are 78 octane E10 I believe.

--

 

[swatski]

Not a Toyota but my new Lincoln with twin turbo 3.0 got 34.7 Mpg on 93 on my run from Austin to Edmond, ok last weekend. The 93 in Austin 3.20 per gallon so if I lived there I would always buy it . Here in the OKC area there is only 1 station that sells 93 and its non ethanol at 4.18 per gallon. I do that when I want to unleash the 410hp to wheels, its a lot fun. The cost difference is not worth it otherwise for me. I only have 110 miles of fun left , unless I want to spend 4.18 per gallon.

I hear you! Here in MO premium/93 octane is available everywhere around where I live, about $3.10 a gallon, so it is not too bad.
No ethanol free around here.

--

 

[swatski]

my new Lincoln with twin turbo 3.0 got 34.7 Mpg on 93 on my run from Austin to Edmond, ok last weekend.

Wait... what!? 35mpg?
Is it a hybrid??? lol, or you trying to enter @veedubtek hypermiling club.
That's pretty impressive. About twice of what I get...

--

 

[2kwik4u]

A few things I thought about on the commute home/back into the office.

There are multiple way for the tunes to work. I have experience with GM tunes firsthand, and that is what I explained. However, other control algorithms can exist. For instance it's plausible that there is a simple multiplier table for timing that watches for knock, and if no knock is detected than it begins to increase until knock is detected. With some hard coded limits, this would allow the ECM to adjust for fuel quality easily. I know GM has implemented a third case of having both a high octane and low octane timing table, and allowing the ECM to interpolate between the two based on a set of criteria that determine fuel quality. There are countless other ways this could work, and I honestly have no idea how the Toyota system works. What I described in my first post of having the ECM rely on sensors to "back off" a hard coded aggressive tune is only one way, and I would suspect how it's working, but I don't know for certain. I'm however pretty certain there are hard coded "stops" on the adjustment that the ECM can make; i.e. it won't let the timing dip too low, or too high. This would be done for engine safety/reliability, as well as a way to keep the controls from going haywire if a sensor suddenly started reporting bad data.

I have a document somewhere in my digital archives that outlines GM 1227749 ECM (ran in Syclones/Typhoons/Turbo Sunbirds in the early 90's). That is one of the most well documented sets of ECM code that I'm aware of. It's outrageously tough to sit down and "read through" because it reads like the technical documentation it is. However it gives some really good insight into how GM's control theory of the time worked. I read it over a decade ago, and the insight it provided was the basis for my work tuning my own vehicles since. Understanding the parameters of the control scheme, and how they will effect the output of the ECM is invaluable in making good judgments in tuning. Even so far as to select what fuel to run. I'll see if I can dig that up and post it.

Another thought on datalogging.....Don't be afraid of this even the slightest. It's like reading a stream of data coming out of any other machine. Hit Ctrl-Alt-Del on your windows PC, go to task manager, and look at the performance tab. Those charts are reading a data stream that the OS generates, and the task manager application is reading and visualizing. Reading the data from your car/truck is exactly the same. The OS on the ECM creates this data stream (As federally mandated in the OBD2 protocol), and publishes it to the OBD2 port under the drivers side dash. That data is streaming there constantly, and all you need to do is capture it and display it. There is very minimal risk of damaging anything when using quality components to monitor. I use This ELM327 Bluetooth Adapter and the Torque Pro App to datalog all my vehicles. This device also reads and clears diagnostic codes if needed, which can be a huge help if you run into problems......Anyway, The PID (performance ID's) listed above should be part of the standard OBD2 data stream. They will give you the insight you need to make a "non-placebo" judgement on if the higher octane is really doing anything or not. Watching (and plotting) timing advance vs throttle input would be a good indication of the "state of tune". Total timing advance on a full throttle (or known heavy loaded hill) would also be very telling.

The results of running 93 for are most obvious on one particular stretch home each day. I-64 from downtown Louisville, "up the hill" to Georgetown IN is a nice long gradual incline. on 87 the truck will NOT maintain 60mph without a downshift. Once it downshifts it picks up speed, then upshifts and loses speed. This cycle repeats until I'm to the top of the hill. With 93, it has just enough more grunt to stay in 6th all the way up the hill and not downshift. I've done this test every day for the last 2 weeks. With cruise and without, the results are the same. The smoother idle, and slightly higher output at part throttle when passing is most likely placebo, but the "hill test" has been my convincing argument thus far. I'm hoping to get Torque setup to datalog here in the next few days, and see how it does towing this weekend. We're headed to the lake on Saturday, and there are 3 good "pulls" on the way there that are steep enough to require a drop from 5th to 3rd occasionally, and have dedicated truck lanes because of the steepness and length of the hills. Sadly I don't have a before with the 87, but will at least get some "after" with 93 I can check on.

And a final thought on fuel mileage vs fuel quality. The only way to really know if this whole thing is worthwhile is to look at a cost per mile of driving. That study I did with my Focus was when money was really tight, and I had to prove to the wife that the car was saving us some money over the Yukon we traded in for it (I was driving 25k+ miles a year, and we were strapped for cash). On top of that she saw that it would run on E85, and then saw that E85 was $1.35/gal. Immediately the thought process was that it would yield the cheapest solution for us. However, with the increased performance of E85 from the higher octane, combined with the reduced mileage due to energy density of Ethanol vs Gasoline, the dollars spent per mile of driving was actually WORSE than that of E10 93 Octane. This wasn't the surprise to me as much as how poorly the E10 87 octane did. It had the highest cost of the 3 fuels I tested, and I would have bet money it was the best. The E10 93 octane fuel ended up with the lowest cost per mile to drive, so that's what I ran in it. It hurt the cashflow situation a little because the fillups were larger chunks coming out than the 87 or E85, but the overall cost to operate was as low as possible......My intention is to do the same thing with this truck this winter. I'm waiting until we put the boat away before I begin the test since towing has such a profound effect on mileage. If I can get a solid month on each fuel under similar driving conditions, then I can make a fair assessment as to which is really the lowest cost to drive around on. This has to be a fact based test as well, there are LOTS of places for the placebo effect to come into play here between the high cost ($75 tank of fuel on 93) vs the perceived performance increase/decrease.

Anywho.....There you go.....sorry for the 1,200 word novel length post

 

[djetok]

Wait... what!? 35mpg?
Is it a hybrid??? lol, or you trying to enter @veedubtek hypermiling club.
That's pretty impressive. About twice of what I get...

--

no its a car, Lincoln MKZ , they aren't rated that high but I was getting that on 93 per the lieometer. Of course its flat ground and all highway at 75 mph. Around here on 91 I get 28 but there is stop and go. On 93 I get 20 around here because I am melting tires from stop light to stop light. The tune actually helps my mileage, when I don't bury my foot on the gas pedal. I am big on tunes. My f150 is tuned, my mkz is tuned, and every car I have ever owned has been tuned (except my wifes)

 

[Betik]

A more objective way to test your theory may be to connect a scan tool that is capable of reading live data and just watch the knock sensor and timing retard readings.

dont give him ideas. He has a family

 

[2kwik4u]

dont give him ideas. He has a family

That's the beauty of scanning/logging your daily driver. Even trips to the grocery store, daycare, school, or dinner can provide valuable data

 

[Sbrown]

dont give him ideas. He has a family

An $80 scan tool has this capability. Don't need anything expensive.