Well, you're still wrong, if that's what you mean. So I guess it doesn't.Originally posted by: Jeff7181
Originally posted by: Pacfanweb
Only if you mean it.
Does it matter?
No, because this isn't about who is right and who is wrong, it is about what is right and what is wrong.
Please explain yourself further. Can't you see that I'm looking at this with an open mind, trying to figure it all out? The way you are explaining it currently does not make sense, or at least I do not have the whole picture.
In the GM book you quoted, it DOES agree with you. But that is only GM, not all cars in general. I am giving you that. But it does not tell us the whole story. Can you answer my questions?
What vehicles does the book pertain to? Does GM produce vehicles that require above 87 octane? If so, is their ECU really programmed for 87 octane like the book says?
It is in black and white in that first Toyota PDF you linked. It takes the data from the sensors, and compares it to a pre-programmed scheme. It doesen't come up with its own program on the fly, it compares the data to the known-good chart, and does what it thinks it needs to do. It is variable, but only to the extent that the pre-programmed scheme allows it to be.
Again, please correct me if I am wrong. I enjoy learning new things.
So are you saying that computer controller cars, considering no problems, always run the perfect mixture, and never run lean or rich?
I was thinking about the article I linked after I posted and wished I hadn't. I can't find all my old links to articles on the subject.
Calling me bullsh!t doesn't offend me.
Pacfanweb, does Saleen remove the knock sensor?
Remember the GM manual could be wrong. Humans write manuals, often containing mistakes. And that's not really something that would be contested by a mechanic and corrected, since repairing a problem is never going to rely on knowing whether the ECM can advance to take advantage of octane ratings higher than specified by GM.
Even at 14.7:1 it's possible for the burn to be incomplete on a molecular level.
You're never going to open up the combustion chamber of any engine and find no carbon deposits, nomatter how accurate the computer controls are.
Nope. But they recalibrate the ignition advance curve to where the timing stays pretty much near full advance all the time, so even if the PCM wanted to, it can't lower the timing enough to not spark knock on lower octane fuel.
The manual for my 98 SHO recommends 93 but says lower octanes can be used but performance may decrease. Is it better to run 93 100% of the time?, or am I ok using 89?
Also, I'm not exactly sure about this but I seem to get slightly less mileage using the 93 octane but its pretty negligible difference or perhaps just my imagination?
Also, I'm not exactly sure about this but I seem to get slightly less mileage using the 93 octane but its pretty negligible difference or perhaps just my imagination?
1. You're okay using 89. The knock sensor advises the PCM on when to pull back the timing.
2. It's your imagination.
3. You will have slightly more power by using 93 because the PCM will advance the timing farther.
There is nothing incorrect about this statement.
However, you are correct in that the difference is negligable - less than 1% throughout the grades. This is because the gasoline refineries can tweak the energy content as needed to even it out.
As far as I have seen, this "rule" applies to all other fuels. Ethanol, propane, natural gas, etc, etc. They all have a high octane, but they do not contain as much energy as gasoline.
1. You're okay using 89. The knock sensor advises the PCM on when to pull back the timing.
2. It's your imagination.
3. You will have slightly more power by using 93 because the PCM will advance the timing farther.[/quote]
Hmm... Alright, but couldn't the advance in timing affect efficiency?
I remember the Honda racing 250cc motorcycles from 40 years ago running regular fuel because high octane was too "slow burning" for the 18k rpm engines in those days.
By the way, didn't Smokey Yunick say that drum brakes were more superior than disks?? Again, this was written in Popular Mechanics 40 years ago...
By the way, didn't Smokey Yunick say that drum brakes were more superior than disks?? Again, this was written in Popular Mechanics 40 years ago...
you have absolutely no clue what you are talking about. you just called an inline 4 engine a V4. and you said 'today's new car is v6' which doesn't make any sense, considering 'today's new car' contains a hybrid electric/4-cylinder engine.
Man, so following that progression, I guess you just piss in the gas tank for a v12 ferrari?[/quote]
nice :beer:
Hmm... Alright, but couldn't the advance in timing affect efficiency?[/quote]Advancing the timing improves efficiency(not universally, but in the context of this post).
Fritzo
Lifer
- Jan 3, 2001
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Wrong. Using higher octane than required will do not harm to your engine. It will harm your wallet, but not your engine. The only thing that octane does is raise the self-ignition point. A spark plug in any engine operating with a stoichiometric fuel/air mixture (i.e. any modern engine) will ignite the fuel/air mixture for a full burn regardless of the octane level of the fuel and regardless of the engine's octane requirements. Octane prevents self-ignition from compression before the spark plug fires, which is a concern in high-compression engines.
Whoever gave you that "information" about higher octane fuel being less clean should not be allowed to touch a car.
ZV[/quote]
Funny, that's the first time I've heard anyone disagree. I've read all over the place and seen it explained that way quite a bit. I've hung out on auto forums for years too. But I don't have time right now to even argue, much less get refs, etc. BTW, I didn't say it'd 'harm your engine' per se.[/quote]
Well, technically, higher octane fuel is less clean because it has to be refined more, I guess
Anyway, I was always told to use 87 unless A) you're getting spark knock, or B) You have a turbo or a supercharger.
use what your car is supposed to use. you may use one step higher on an older vehicle due to carbon deposits (87 to 89), but going from 87-91 is worthless unless you're modified.
fyi cars in hot climates may also use a spark plug that is one step colder. this is from the honda owner's manual.
fyi cars in hot climates may also use a spark plug that is one step colder. this is from the honda owner's manual.
No. It will need to advance the timing with higher octane to maintain the same efficiency, and will probably in reality have better efficiency.
Advancing the timing improves efficiency(not universally, but in the context of this post).[/quote]
Got it, thanks for the info Eli, Pacfanweb, I've been learned!
I have a 99 Trans Am and if I use regular gas it will ping and gets about 5-7 mpg less than on premium. The premium is slower burning and harder to ignite which eliminates the ping or knocking. If the engine pings it will retard the spark advance to compensate and that reduces the effeciency of the engine and causes a big loss of power also. Low compression ratio engines get by with less octaine rating.
On older non computer controlled engines with high compression ratios in a pinch you can actually get by with using regular and adding a couple pints of diesel fuel to the mix to raise the octaine rating, it smokes like crazy but it works .
On older non computer controlled engines with high compression ratios in a pinch you can actually get by with using regular and adding a couple pints of diesel fuel to the mix to raise the octaine rating, it smokes like crazy but it works
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