Tomas

Once again...


and


Tom

INFINI

iTrader: (1)

K, this does not tell me in any way specifically that it was designed to use 87. Just says:

Fuel Type:
Unleaded gasoline, Octane 87 (research Octane 91) or higher.

The reference the Oxygenates in gasoline do not say it's made to use 87 but "no lower". Can you elaborate on what significance Oxygenates in gasoline has?

Reason I keep bringing this up is so I do not need to debate with anyone who says I should use better octane.

Even the "(research Octane 91)" reference drives me nuts.

frogbox

here is a little reading on them...... http://www.eia.doe.gov/emeu/steo/pub/special/mtbe.html

INFINI

iTrader: (1)

thanks I will read it tonight.

Just to be clear The reason I ask is cause I do not want to doubt the choice of octane I chose at the pump.

Allot of people in my thread here said the xA was designed for 87/ hinted at it or the like. But I wanted direct documentation on this, if any.

K now gonna go read your article.

Tomas

I would suggest that the manufacturer recommending that the car be fed "87 octane or higher" fuel is a pretty good indication that they designed it to run on 87 octane fuel.

Tom

INFINI

iTrader: (1)

I disagree. That says 87 or higher. Not 87 is what the 1.5 ltr is designed for but you can use higher.

I know I might sound crazy but I think I can have a reasonable expectation of exact interpretation when it comes to Manufacturers information.

I am a regular consumer that does not know much about these things or the technical language either. I am very smart and learn quickly so why I ask so many questions

So When I hear from a certified mechanic that I "could still use 87" like it's really not recommended and hear from posts differently it gets all confusing.

vintage42

Last summer I emailed Scion to ask if the engine got any advantage from using an octane higher than 87. I felt sure that 93 octane would help hard acceleration and hill climbing, by reducing the need for the knock sensor to make the ECU retard the ignition timing. Scion's reply was:
To me that says that the ignition advance curve programmed into the ECU will minimize knocking on 87 octane under high load and rpm. The advance curve is designed to not give enough advance to cause knocking in normal driving. And if it does occur, the knock sensor will react instantly to tell the ECU to retard ignition to put out the knocking before the driver is aware of it.

The following manuals explain how the knock sensor works, and that it and the ECU cannot prevent knocking if the octane is less than 87.

Tech Literature explains what the knock sensor does:
"DIAGNOSTICS - SFI SYST
DTC P0325 - KNOCK SENSOR 1 CIRCUIT - CIRCUIT DESCRIPTION
Knock sensor is fitted on the cylinder block to detect the engine knocking. This sensor contains a piezoelectric element which generates a voltage when it becomes deformed, which occurs when the cylinder block vibrates due to knocking. If engine knocking occurs, the ignition timing is delayed to suppress it."

The Owners Manual, Section 2, Page 114 explains that below 87 octane, the knock sensor and the ECU cannot prevent knocking:
"OCTANE RATING
Select Octane Rating 87... or higher.
Use of unleaded gasoline with an octane rating or research octane number lower than (87 octane) stated above will cause persistent heavy knocking. If it is severe, this will lead to engine damage."

All this leads me to think there is a short benefit from high octane. The Tech Manual says the knock sensor is working at 87 octane to suppress knocking by telling the ECU to reduce the amount of timing advance. The knocking is trying to happen under high load and rpms.

If higher octane can avoid triggering the knock sensor, the engine will have higher performance at those moments when knocking would be suppressed on 87 octane - such as hard acceleration or hill climbing. The advantage of high octane would only be at those times.

INFINI

iTrader: (1)

That is great info on the reply from Scion. Thanks.

Strange why I was not using under 87 at all, ever. Not available in CA I think. So why with all that tech you just explained would there be such a loud engine "knocking" or piston noise (clanking)?

Any who, I got my Q's answered directly so going sort of off topic like this is ok by me.

Tomas

As said earlier, if you used cheap gas without adequate detergents and with possibly poorer quality, you may have deposits built up over time in your engine that can DEFINITELY change the fuel requirement for the engine to a higher octane, because it changes the compression ratio by taking up space...

If that it the case (not saying it is with certainty, but that is what it sounds like), you need to get rid of those deposits. The easy, cheap way to try is to use an appropriate cleaner additive, and to stop using gasoline with inadequate detergents. If the cleaners don't work, it often ends up being teardown time to correct the problem and the damage caused.

Bottom line, as always, is not to use fuels with inadequate detergents, and if you must, use an appropriate cleaning concentrate to keep buildups from happening.

What makes the problem so difficult to convince people of is that the cheap fuels run the engine just fine, and it isn't until extended use of them allows enough built-up deposits to cause problems that any difference from the quality fuels is noticed. By then it is often too late.

As the vehicle manufacturers repeatedly say, use fuel with adequate detergent packages (Top Tier) to prevent eventual slowly developing problems.

If one feels using the correct fuels is too costly, one can usually look forward to eventually spending the same money or more to fix the problems allowed by low detergent levels, PLUS have the annoyance of a poorly running engine as the problem builds up.

I can't say it any more clearly.

As always the choice is the owners...

Tom

vintage42

A friend here in Louisville put 60K miles on her Element, always buying the cheapest discount brand gas she could find. Over the last 30K miles the MPG sank down into the low 20s. Finally the engine started missing and she took it to the Honda dealer. The dealer said the valves were loaded up with deposits and charged $500 to run a BG brand chemical cleaner kit through the injectors. The Element ran better and she gave it to daughter who flew in from Portland to drive it back home there. The Element made it to St Louis before it began to miss again.
I have run my Mazda truck for 150K miles on Chevron, a Top Tier gas containing detergents. It has never had a problem.

INFINI

iTrader: (1)

I got some fuel cleaner today.

Tomas

...hope you got a good one!

Good luck!

Tom

INFINI

iTrader: (1)

For the past month or so since this problem occurred with the AC busting and the really bad clanking engine I have not filled up at any stations but the ones on the list form the site. I also have pumped mostly 87 and 89 in that time.

The loud engine noise went away 2 days after I started using better gas + different more name brand stations.

Tomas

Some more very good reading:

http://www.chevron.com/products/prod...etin/motorgas/

See section 6 about deposits, but ALL of the info is good, and worth knowing.

Tom

Spiderbox

i had that problem with the ac line being damaged as well. one dealer quoted me 1200 bucks to fix it, got it fixed at a different toyota dealership for 500.

i think it was damaged from a rock or something, it looked like it was physically damaged from something hitting it. could have been another car bumped into me while it was parked in the street somewhere.

both dealerships didnt give me any problems with the mods on my car (i have the perrin pulley too) but they stated pretty clearly that it was not covered by warranty.

INFINI

iTrader: (1)

Yeah it was the condenser but the compressor broke also due to "whatever". So in the end I bought an aftermarket Condenser for $230 and installed it myself with my Mechanic. Then had them do the warranty on the Compressor and the Array. They quoted $1,800 in savings.

I am quite happy with the end results even thought I had to work my but off to get it done

Mightygnu

but its done now isn't it james. good seeing ya tonight, car is looking good as usual

INFINI

iTrader: (1)

LOL, you too. Yup now I can try and avoid the kind of accidents I almost got into tonight on the way home. WOW! I almost side swiped some one in the fast lane when I was cutting into the 10 W.

I came " close.

Mightygnu

ouch. well good to hear your alright. hopefully see ya soon.

INFINI

iTrader: (1)

LOL. I got off the highway for a breather after that.