Lander

Ok, I've had my box now for a few weeks. I got it with 170 miles on it. I ran the gas down to the warning light and then refilled with the highest octain at the local Mobile station (89 octane @ 505 miles) After a few miles I noticed I have lost some of the pep in the engine. I couldn't figure it out.

I called down to the dealearship and asked them what gas they filled it up with before I bought it and they said regular (87 I'm guessing).

After that tank, this past weekend, I filled up at another station with their highest octane, 97, and felt no change.

Any Ideas?

ltj42884

dont run the tank till its almost empty...any junk that was in the gas will clog your injectors and that will cause you to lose power...fill up at lik a quarter tank or a little less...also you dont need to use high grade gas...it will work the same...somebody else will have more info on that

Lander

I ran it to the light to check gas milage. DO you really think that could be the problem with only 500 miles on my box?

grzydj

You don't need to put higher octane gas in your xB. It's a waste of money. It should run just fine off of 87 octane.

As for your power loss, it might just be a part of the break in process. It should feel like you're getting more power after a few hundred more miles.

PS. Don't run your tank so low. It's a bad habit to get into.

ltj42884

it doesnt matter how many miles you have on your car...it matters what kind of junk is in the gas,..if you wanna check your mileage just average 2 tanks...you dont have to run it to empty...when you fill up just divide your mileage by the gallons you put in

ETsBlackBox

Higher octain gas gets worse milage than low octain due to the fact it does not combust completly. Also the car is ratedf for 87 octain highter octains gasses are ment to prevent knocking in cars tht ran on leaded gass and cars that have high horsepower motors. Stay with the 87 that is what the engine reall yneeds

Fujiz_xb

use 87 as it states in the manual.. you are not driving a camaro to use higher octane..
stick to 87 .. that is the best diet for the hamsters running our boxes.

Ducman69

I used to think that as well, but its not the case. Gas is sucked from the bottom of the tank regardless, passes through a fuel filter, and gets sloshed around when fueling and driving plenty anyway. It is good advice not to run on fumes too often as it can burn out the fuel pump (almost universally mounted in the fuel tank)... well and you'll look like a tard pushing your car or walking with a gas can.

Your timing was set with 87 octane in mind. So you should use that... maybe you got some bad gas. *shrugs* Its under warranty though, so why not just bring it in? They are paid to diagnose and fix these issues.

Lander

The box goes in tomorrow. I will have them check that as they do the other warrenty work to my box.

P.S. I found the designer of the XB
https://www.scionlife.com/forums/viewtopic.php?p=650341

mfbenson

Higher octane gasoline actually has less chemical energy in it so if you use it, it would be normal to see a slight performance/mileage decrease unless you also modify the engine timing to take advantage of the resistance to detonation. Our engines are set up to get max power from 87.

Also, the higher octanes are also the same fuels the gasoline companies tend to load up with detergents. In a brand new car the detergents are just wasted filler that do nothing beneficial and steal even more power away because they do not burn with the same energy as pure gasoline.

Lonely_Raven

Hey brother, just a heads up.

If you only have 500 miles on your box, then it's not broken
in yet.

I had weak gas milage until about 1100 miles. Before
that, it bounced a bit, after 1100 it leveled out at a
consistant 33MPG.

Also, different gas will react differently in some cars. I've
grown used to using ONLY Shell. Not saying it's the best,
but both my Porsches have more pep with Shell, and my
SAAB got over 330,000 miles without any engine issues
using only Shell and regular oil changes (till it was hit by a
man with poor judgement and even poorer sense of timing).

I agree with the post above that it's probably not an issue
how low you let your tank run, and that whole sediment issue.
The Federal government put out a requirement that ALL
gas stations have their below ground tanks upgraded to
modern ones for safety and the environment. So as of Jan 1
(or some other recent date, I can't remember) all stations
had to be upgraded or closed down. Sediment should not be
an issue.

So yeah, finish up your break in peroid, use quality gas,
and maybe take the car to be checked out if the dealership
doesn't give you crap for bringing "little things" to them
as I'm sure they'll see it.

Lander

I think I know why now.

The higher in octane that you go, the longer the hydro-carbon chains are. What does this translate to in the "real world"? The longer hydro carbon chains, although containing more potential energy, have less surface area at the molecular level. This results in a longer burn -the energy being spread along a longer cuve. The lower octane, containing less potential energy, will more readily release it, and will tend to do so all at once.

Since the scion has a short stroke and low compression it can't effectively use the higher octane. Time to get a hose and suck some gas. I will confirm this once I put in the 87. I guess I missed that spec in the manual.

Credit to: Yergi

SOBAY310

But then again you have people who fill up with 92 and it runs fine. I think when you start to stress about the performance of things you end up feeling or hearing things that aren't really there. You know what I mean? We all do it. I know it makes people sound like their hallucinating, but you know what I'm talking about.

Lander

I wish that was the case, but it was way too noticeable.

Sublimize23

the engine will retard the timing as a result of the knock sensor going off, this is probably what is happening.

Chimmy3

I had problems with mobil gas... but ppl tell me gas is all the same... shrug..

you can probably find the posts a while back

I'd say stay away from mobil gas... try a different brand and see if it gets better. (btw the hightest octane was 89? weiiird).

ROBUPNYA

so everyone is saying 87 octane is the best for the box....i didn't get to read that in the manual.....

Rion

Higher octane gasoline is for cars that require it.

A car that requires 92, will retard timing if you put in 87 and you will lose power.

A car that is recommended to use 87 CANNOT advance timing and make more power from 92 octane PERIOD.

No matter how many times we state the facts, there will always be people who insist that 92 octane makes their xb/xA/Civic/Cavalier sooo much more powerful.

To those people, I extend a thank you from ExxonMobil, BP and the rest for making them rich with their foolishness.

Rion

Actually the 1NZ-FE has a long stroke. It's undersquare, not square or oversquare like most Honda engines. That's why it has decent torque for its size and isn't happy revving up at 6500+ rpm.

High octane fuel is more resistant to pre-ignition. That's it. Most people imagine it has "more power" in it or something, it doesn't. It just reisists ignition more so it can be used in higher compression engines and/or turbocharged cars with more advanced timing without pre-igniting and knocking/pinging. It does nothing for the average car designed to run on 87 octane.

All gasoline comes from the same refineries too. The only difference between Shell and BP and Exxon and Joe's brand is the additive package. Except for, Sunoco I think it is, that has that "crystal" clear gasolne that looks like water, that is refined seperately AFAIK, but it's just a gimmick, though I've heard it does have lower emissions.

Regular gasoline has the same additives as premium now for the most part. There was a time when premium has additives and regular had none, or fewer, but the federal government stepped in and required a standard there.

Buy 87 octane from the store on the corner people. Don't put in STP fuel additives or Octane Boost. There is no reason and nothing to be gained and you may even cause yourself problems long term.

ROBUPNYA

87 IT IS!!!