Difference with high octane?

May have to drive a bit with my scanner
Thanks

 

6th gear, below or at 2k rpms ~80% calculated load. 100+ F IAT.
You'll hear it
To get benefits of high octane, need to update ecu for that octane. This is 92 octane after reworked tables

 

There are some gaps in this description. Flame propagation is not a constant "speed".
"Knock" is the result of uncontrolled (too fast) combustion pressure build up.
It is the combined pressure of mechanical compression AND early combustion that causes a
spontaneous ignition across the fuel/air charge. PING, or KNOCK or some call it Dieseling.

 

Oh, there are gaps for certain, there are complete novels that can be written on the subject (and have been). The fun one is when manufactures use "dieseling" in gasoline cars to increase fuel efficiency, which is what Mazda is doing IIRC.

I guess I don't understand though, are you agreeing or disagreeing?

 

Yes, there is so much. Too much for this thread.
What I agree to is that "hi test" includes additives that suppress the spontaneous ignition that is caused by heat and pressure.

The "benefits" of high test, related to engine performance, is to allow greater combustion pressures to occur at favorable orientations of the engine mechanical parts.

BMEP is everything ......

 

yes it reads knock sensors to base the timing. that being said i have never heard or experienced ping in my truck. its only ran 91 since day 1 though. worse engine ive ever experienced is the new f150 5.0s. they genuinely knock and bang like a diesel at times

 

i use the "Car Scanner" app. i think it's free.

 

Try premium gas and tell me the truck doesn't run better and smoother. I did get maybe a half a an mpg better with 93. I think your just not in the throttle as much. Other thing I bet premium fuel will a lot less carbon building up on the inside of the engine. Direct port injection is known to have more carbon build up

 

Our trucks got a direct injection cleaning cycle though, so carbon build up is not an issue on the 3.5L.

 

Have you ever seen the oil after 5k? It's thicker then the new oil. That all carbon that got "cleaned" and wash by the oil. I'm willing to bet someone that runs premium gas all the time has cleaner oil also. I've never tried but thinking of experimenting. Maybe someone that runs it all the time can chime in.

 

i don't think octane will effect the oil quality at all, oil is always going to look dirty after 5k miles.

 

What "qualities" might be present in "premium" / hi test/ ethyl gasoline that would limit carbon deposition?
I don't think anti knock (tetra ethyl lead is out of the picture) I'm thinking chemistry, and have no references. I do know some stations advertise "drive your engine clean", but that come-on is not limited to hi-test.

 

If I wanted to make use of the engine design and tuning, I would NOT be asking for >80% power at 2k rpm in 6th. That I would term "Abuse".

 

No one stops you..
This is the reality of Stock tacoma powertrain tuning.

 

That's why I get by on 87 ... I don't push too hard on the go pedal. ;-)

 

I have a 2nd Gen, but back when regular was under two dollars a gallon and premium was less per gallon at most wholesale clubs (BJ's, Costco, Sam's Club, etc), I would fill my truck up with 93 at BJ's just to see what would happen; I observed an improvement of a couple miles per gallon, give or take, but the difference wasn't enough to justify totally switching to 93...

 

In a freak occurrence, my head gasket started to fail at less than 130K miles (I think), disguising itself as age-related oil consumption; I was consistently going through a quart of oil every 3,500 miles or so, and in April 2021 a friend of mine noticed that there was oil in the coolant reservoir. My regular mechanic performed a plethora of tests (compression test, leak down, etc), and came to the conclusion that my head gasket was likely fine. Another mechanic in my area, who happened to be a certified Toyota master tech, gave my truck a once-over and also deduced that the head gasket was fine. I have been running full synthetic oil since just before 80K miles (January 2018), and Mobil 1 since just shy of 85K miles; I started out with regular full synthetic 0W20, and then after the first time my old mechanic (who I haven't used in years) noticed I was a quart low, I upped it to 5W20. I may have upped it to 5W30 at some point, but that wasn't very long and I upped it to 5W30 sometime in 2021.

In February 2021, my mechanic got COVID and I had to bring it to the dealer because I needed an oil change; I provided 10 quarts of Mobil 1 and just paid labor. The aforementioned "oil in the coolant reservoir" that my friend Jeff noticed was attributed to an absentminded dealer tech using the same funnel to add oil and top off the coolant. Like I said above, I switched to 10W30 and my truck's oil consumption was reduced, but my gas mileage went to shit (13-14 MPG around town sometimes and less than 20 on the highway). My late friend Jim helped me replace the spark plugs in October 2021. My truck got a frame replacement, courtesy of Toyota, in November 2021.

It was after the frame replacement in November 2021, and before the head gasket replacement in October 2022, that all sorts of shit started to go wrong with my truck. This included the alternator, the oxygen sensors, a steering U-joint, and the driveshaft U-joints. Another TW member told me that a friend of his who went through a frame replacement had all sorts of things go wrong with his truck after the frame was replaced.

In late 2021-early 2022, my truck would misfire on startup from time to time, and though I never got a CEL a code scan revealed a misfire on one of the cylinders. My mechanic replaced all four ignition coils and a fuel injector on that specific cylinder. This briefly corrected the misfiring issue, but not for long. In April 2022, a friend of mine, who owns a similar truck (2005 RC 5-lug, but with a manual transmission), attributed the misfiring to the fuel injection system and ran EFI cleaner through the fuel injection system. This worked great for the longest times, but then in July 2022 something happened that I ignored but should not have; I had topped off the coolant at some point and didn't secure the cap on the coolant reservoir. This resulted in coolant spewing out of the reservoir and all over the engine bay, which led to me freaking out when I smelled coolant after get home one night; I popped the hood, discovered the mess underneath the hood, and added more coolant.

A day or two later, I had the same problem with the cap mysteriously popping open. That evening, I started the truck after ending a car show in Pottstown (Again, this was July 2022), and the temperature gauge immediately shot up to the red for a couple of seconds before dropping back down to the normal level. My fuel gauge had occasionally been inaccurate (it still is occasionally), and at the time I attributed it to the reservoir cap not being secured; I had this "temperature gauge surge" occur a couple of times that summer, but made a trip to upstate New York (Syracuse, Rochester, then back home) in mid-July without issue. Turns out that the "gauge surge" was my truck trying to tell me that the thermostat was failing...

 

I opted to have the water pump replaced when the dealership did the frame in November, because my truck had 140K miles and I was told by TW members that water pumps tend to fail around 145K. Since the engine had to removed as part of the frame replacement, I only had to pay for the water pump and not the labor associated with installing it.

Fast-forward to September 2022, with countless trips to Carlisle for car shows and the aforementioned long weekend in upstate New York for another car show, and no issues...

One Saturday in September, I drove to a van show at the Schuylkill County Fairgrounds and then decided to do some exploring in Centralia before heading home. My parents and I were supposed to leave for a vacation in Massachusetts the following morning (Sunday), with my parents in my dad's Yukon, and me driving my Tacoma with our dog Porter in the front seat.

I stopped for gas at a Wawa, in Hamburg (about an hour from Centralia) if I remember correctly; I started the truck, and the temp gauge did the "surge" before returning to the normal level. I drove about another hour to Hatfield, PA with the A/C cranked and no issues; I stopped at yet another Wawa on 309 in Hatfield, not because the truck needed its tank filled, but rather because I needed to empty mine. I took a leak, and when I started the truck afterwards, it legit overheated; I was freaking out because my truck had never done this before in 13 years of ownership, and something like 157K miles over the course of those 13 years. I called my parents, and a random Wawa customer checked under the hood. We came to the same conclusion, that the thermostat was stuck; I was also 99% sure the head gasket had blown...

I let the truck cool down, and was able to limp it home with the heat cranked, though the heat didn't seem to work very well and it would start to overheat again whenever I stopped at a red light; I was on the phone with @shakerhood during this fiasco. I made it home, and we delayed the trip to Massachusetts due to the truck's problems; I topped off the coolant the following morning, and though it wasn't overheating, the heat would not work.

My mom agreed to let me use her Nissan Murano to drive up to Massachusetts, while I contacted my mechanic; I dropped the Tacoma off with my mechanic on Monday morning, and then we left for Massachusetts. I was positive that I would need a new head gasket, but my mechanic Pete did a leak down test and a compression test, in addition to pressure-testing the radiator. None of these pointed towards a blown head gasket. My mechanic discovered that the thermostat had failed due to old age and gotten stuck closed, and replaced it; I picked up the truck when we got back from Massachusetts and drove it for two or three weeks with no issues.

One night in October 2022, while driving home from dinner with my friends, I turned on the heat due it being chilly, and discovered that I had no heat AGAIN. However, this time the truck wasn't overheating and seemed to run just fine. I checked both the radiator and the reservoir, and there seemed to be plenty of coolant, so another friend of mine who used to be a mechanic attributed it to air bubbles in the system from the recent thermostat replacement and coolant flush; I happened to be meeting this friend in Centralia for some exploring the morning after the heat quit working, and after adding some coolant, the heat worked when the truck was moving; I drove up to Centralia and back without issue. This was in October, and I had my Tacoma done up in the traditional "Zombie Response Team" livery; I took pictures of the truck up in Centralia, and then went to a friend's house back home in Bucks County so she and her boyfriend could pose with the truck.

I initially pulled into her driveway but she told me to pull the truck into her yard, and when I started the truck to move it onto the grass, it did the temp gauge surge again...

 

That final "surge" happened on a Sunday; I called my mechanic on Monday, and he told me to bring it by. Neither of us knew what to expect, but the news wasn't good. There was a strong smell of coolant at the tailpipe that hadn't been there before, and the pressure test of the radiator wasn't so good this time. My mechanic confirmed my suspicions, and I had a decision to make; I did not have the money to pay for a head gasket job at the time, and I wasn't about to sell my beloved truck that had just gotten a new frame and three grand in bodywork that I didn't have to pay for! Luckily, my dad stepped in and agreed to pay for the head gasket job as an early Chrismas present. My mechanic wanted just under five grand for the job, but my truck would be out of commission for about 10 days and I wouldn't have anything to drive. Before we knew the engine was salvageable, Pete also quoted me almost eight grand for used 50K-mile engine out of a totaled 2011 Tacoma. My dad was willing to pay this, but research told me that the original engine was fine; I went to Thompson Toyota, which had done my frame, and to my absolute shock I got them to meet my mechanic's price (it would have been about ten grand normally). I would get a loaner car while the work was being done and it would take less than a week; Thompson did the job in three days!