Just filled up the tank with 91 octane premium fuel

[BLAZINBLUEVITZ]

different thread SAME opinions.......

[The little red pill]

I just like the fact that running 91 octane gives me that 50 extra horse power. In fact, I raced a Mustang the other day and blew it's doors off! At the next light he asked me how I beat him. My response, "91 Octane Baby"!

P.S. I also have a AEM sticker on my car which throws in another 5 horsepower, but that's just our little secret!

[TheSilkySmooth]

if you have a CAI and open exhaust the ECU might retune over time for the higher octane and you might get some more torque, but I never found the need to add more than 2 gals to the rest of the tank in a mix to get all the octane the engine needs. try mixing in just 2 gals of 93 at a fill up of 87. Our engines are High compression and the eCU can start to retard timing when you get carbon buildup over time. A littel more octane can help. MAy car is starting to ping/knock at starting off in 1st gear at 20K miles on the odo. You dont drive hard enough to clean out this carbon, unless you run the car at WOT 3rd and 4th gear on the highway more than a couple minutes a day. That can clean it out. An melt your 2 layer exhaust pipe too!

[07WYarisRS]

Originally Posted by TheSilkySmooth

if you have a CAI and open exhaust the ECU might retune over time for the higher octane and you might get some more torque, but I never found the need to add more than 2 gals to the rest of the tank in a mix to get all the octane the engine needs. try mixing in just 2 gals of 93 at a fill up of 87. Our engines are High compression and the eCU can start to retard timing when you get carbon buildup over time. A littel more octane can help. MAy car is starting to ping/knock at starting off in 1st gear at 20K miles on the odo. You dont drive hard enough to clean out this carbon, unless you run the car at WOT 3rd and 4th gear on the highway more than a couple minutes a day. That can clean it out. An melt your 2 layer exhaust pipe too!

our engines are NOT high compression... my street bikes run 200psi plug per cylinder and run on 87 octane... guess what they have less then 10:1 compression ration.

The ECU will not re-tune for higher octane...
The only time it will make a difference is if the engine is knocking... then the knock sesor will pick up the engine knock and retard the timing.. it won't change the fuel maps to compensate.

Spark knock AKA PING is completely normal and just means the engine is running efficiently...

running a lower octane fuel will reduce carbon built up as it has a lower flash point and will burn more efficiently and completely... Also start running a TRUE synthetic like Amsoil or Redline with no mineral oil or by products that cause deposits to form and after 10 years you engine will still be 95% carbon free

[TheSilkySmooth]

Originally Posted by 07WYarisRS

our engines are NOT high compression... my street bikes run 200psi plug per cylinder and run on 87 octane... guess what they have less then 10:1 compression ration.

The ECU will not re-tune for higher octane...
The only time it will make a difference is if the engine is knocking... then the knock sesor will pick up the engine knock and retard the timing.. it won't change the fuel maps to compensate.

Spark knock AKA PING is completely normal and just means the engine is running efficiently...

running a lower octane fuel will reduce carbon built up as it has a lower flash point and will burn more efficiently and completely... Also start running a TRUE synthetic like Amsoil or Redline with no mineral oil or by products that cause deposits to form and after 10 years you engine will still be 95% carbon free

So 10:1 in the Yaris is NOT high compression? BAH! 2) The ECU is CONSTANTLY adjusting the fuel trim for proper running as required!
3) How do you know if the timing is in retard (without a scan guage) on WOT?

All that said, I usually run regular. If the engine is healthy, and NOT carboned up, it should run OK on 87PON. I think I cooked my cat#1 from driving too hard and have to get it replaced with the high flow ( for free!?) on the TSB EGO35-06 .... Car is feeling lazy and getting choking sulphur smell in the cabin when I whomp on it

[ROCKLAND TOYOTA]

Originally Posted by TheSilkySmooth

I think I cooked my cat#1 from driving too hard and have to get it replaced with the high flow ( for free!?) on the TSB EGO35-06 .... Car is feeling lazy and getting choking sulphur smell in the cabin when I whomp on it

WRONG, your cat was doomed from the start. HENCE the TSB from way back in the begining of 2008....

[TheSilkySmooth]

Originally Posted by ROCKLAND TOYOTA

WRONG, your cat was doomed from the start. HENCE the TSB from way back in the begining of 2008....

Whadya mean - its doomed to fail and just a matter of time b4 it clogged? RockToy - Does the TSB concern the #2 cat further back, or, the #1, Or the pipe in between? Sorry for all the Q's. You think they will give me a hassle(the old melted grocery bag story) ? or is there a back pressure test that it would show up on? Thanks for the help man

[BLAZINBLUEVITZ]

^^ the naysayers will NEVER believe you.....

[supmet]

I run 91 every once in a while, and it does feel smoother starting, accelerating, and idling.

Could it be a placebo affect? Maybe
Is it only a 2 dollar placebo, if it is? Yes


With the octane specific argument aside, aren't their cleaners and additives in 91 that aren't found in 87 at some gas stations??

[427chev]

Originally Posted by supmet

I run 91 every once in a while, and it does feel smoother starting, accelerating, and idling.

Could it be a placebo affect? Maybe
Is it only a 2 dollar placebo, if it is? Yes

Not only could it be, it is.

"CAR AND DRIVER" ran an article on this that included some objective testing of several vehicles. There was absolutely NO difference between regular and premium gasoline in vehicles that recommended regular (e.g. 87 octane).

There was a difference in vehicles that recommended premium, since running regular in them retards the spark and changes the engine mapping to the lower octane map.

[2009Toyotoad]

Originally Posted by supmet

I run 91 every once in a while, and it does feel smoother starting, accelerating, and idling.

Could it be a placebo affect? Maybe
Is it only a 2 dollar placebo, if it is? Yes


With the octane specific argument aside, aren't their cleaners and additives in 91 that aren't found in 87 at some gas stations??

Bingo! We have a winner. Big oil figured out a long time ago that to charge a premium price you need to create a positive preception that the vehicle "just seem to" run smother or more powerful when spending the extra $.10 to $.20 a gallon.

Some oil companies even figured out that they can package the stuff and give it fancy names like "Octane boost, Techron, or fuel system cleaner."

Now there is nothing wrong with buying or using these products. These products do clean the system of carbon crud. However, you can get almost the same effect from running WOT on 50 miles of back country road.

Since some of us don't have 50 miles of WOT roads nearby, these additives are a reasonable substitute.

Just don't fool yourself!

[Aothachos]

DAMMIT DARKMOON87 look wat you started lol, this is going to be the hot topic of arguments, like i said I know what i feel with 91 octane and I'm not changing, i don't mind putting in extra couple dollars for better fuel =)

*better fuel* watch someone say something about that lol

but yea im not convinced to switch to 87 so =) LET THE DEBATE CONTINUE!

[nerp]

All octanes have detergent in them. It's a bit of a misnomer to say that using 93 octane will "clean out" an engine that normally requires 87.

[darkmoon87]

I love how I started the thread asking about the "smoothness" and the thread turned into a gongshow arguements about MPG and power gains...sigh lol

[DerFlosser]

Originally Posted by darkmoon87

I love how I started the thread asking about the "smoothness" and the thread turned into a gongshow arguements about MPG and power gains...sigh lol

I agree....and the only point that I ever really "tried" to make is that it's definitely possible and not "placebo" that it starts and idles smoother.

[dybbuk]

And 427 seemed to be agreeing with you. However, he also said that smoothness was actually bad for the vehicle. Personally, I don't know much about engines (I am NOT a mechanic), but, I can read. It seems you guys aren't reading each other's arguments. It comes down to that it seems; yes, on higher octane fuels it will run 'smoother', but, it will also generate less power.

[427chev]

Originally Posted by dybbuk

And 427 seemed to be agreeing with you. However, he also said that smoothness was actually bad for the vehicle.

Show me where I stated that "smoothness is bad for the vehicle."

I NEVER stated that. Please don't put words in my mouth again.

Originally Posted by dybbuk

... It comes down to that it seems; yes, on higher octane fuels it will run 'smoother'...

Please produce third-party empirical evidence to support your claim that higher octane gasoline will cause a modern engine that's designed to run on regular gasoline to "run smoother."

Good luck finding that.

Have you ever heard of the "power of suggestion?" That's what's responsible for any "improvements" that are being claimed in using premium fuel in a Yaris. Objectively and empirically speaking, there are no ACTUAL improvements.

Medicine routinely demonstrates this phenomenon in what's known as "the placebo effect." People "feel better" when they eat a pill that made of compressed flour, for example, as long as the researchers tell the study group that it will make them feel better.

[nerp]

Yeah, it's placebo.