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Dave

Fuel Grades - Is Premium Better?

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Don't forget that using a higher octane fuel in your car also has a psychological advantage.

Whether it is true or not - you feel like you are helping your car to run better.

Those extra pennies per gallon and maybe a few more miles per gallon makes you feel like it is a good deal.

For all those using higher octane fuels in your cars - keep on smiling!

 

That's not a very good reason. Unless maybe you drive your Corolla like a race car. Oddly enough, back in the day when I had a Escort GT it was made for 87, but I could top out faster (top speed) with a higher octane fuel.

 

If you live in a state where you can get 89 for the same price as 87, I would.

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trap
Don't forget that using a higher octane fuel in your car also has a psychological advantage.

Whether it is true or not - you feel like you are helping your car to run better.

Those extra pennies per gallon and maybe a few more miles per gallon makes you feel like it is a good deal.

For all those using higher octane fuels in your cars - keep on smiling!

 

That's not a very good reason. Unless maybe you drive your Corolla like a race car. Oddly enough, back in the day when I had a Escort GT it was made for 87, but I could top out faster (top speed) with a higher octane fuel.

 

If you live in a state where you can get 89 for the same price as 87, I would.

It may not be a good reason, but I bet it is the reason some people use a higher octane rated fuel.

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Whatever the owners manual specifies, is what I would use and most often regular (87 octane) gasoline is called for.

 

I used to be one of those people who believed that an occasional "treat" of premium (93 octane) was good for the car. It SEEMED to run better and I was lead to believe that there were additional additives and cleaners that would clean and help maintain the fuel system. Basically, all your doing is throwing away your money. If you don't need it, don't use it!!

 

Actually, with gas prices the way they are now, I can't really image anyone WANTING to spend more than they have too!!! :rolleyes:

 

Just a thought :unsure: ...........................

 

Regards,

 

timkedz

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Whatever the owners manual specifies, is what I would use and most often regular (87 octane) gasoline is called for.

 

I used to be one of those people who believed that an occasional "treat" of premium (93 octane) was good for the car. It SEEMED to run better and I was lead to believe that there were additional additives and cleaners that would clean and help maintain the fuel system. Basically, all your doing is throwing away your money. If you don't need it, don't use it!!

 

Actually, with gas prices the way they are now, I can't really image anyone WANTING to spend more than they have too!!! :rolleyes:

 

Just a thought :unsure: ...........................

 

Regards,

 

timkedz

I agree totally, that's why I use low octane, cheap gas.

I think all the hype about higher octane being better for your car is pure propaganda.

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Whatever the owners manual specifies, is what I would use and most often regular (87 octane) gasoline is called for.

 

I used to be one of those people who believed that an occasional "treat" of premium (93 octane) was good for the car. It SEEMED to run better and I was lead to believe that there were additional additives and cleaners that would clean and help maintain the fuel system. Basically, all your doing is throwing away your money. If you don't need it, don't use it!!

 

Actually, with gas prices the way they are now, I can't really image anyone WANTING to spend more than they have too!!! :rolleyes:

 

Just a thought :unsure: ...........................

 

Regards,

 

timkedz

I agree totally, that's why I use low octane, cheap gas.

I think all the hype about higher octane being better for your car is pure propaganda.

 

It usually is. However, if you have a car with knock sensors and a ECU trying to find a optimal tunning, then it might not be. I'm not claiming that a Corolla can get better performance from 89 octane fuel, but I've actually read that the ECU can only take advantage of 87 octane fuel. I forget where I read that, but it makes no since to me, since the ECU doesn't know what kind of fuel is in the tank. It would really come down to how much can the ECU advance the timing when it is shooting for a optimal tune. I think only someone who helped program the ECU would know for sure.

 

I have a Mustang that runs on 87, but I can manually bump up the timing and get more power with 89 pump. With current gas prices, I don't do it very often, but it is a easy way to get some more power. I would probably put 89 in my Corolla if I were driving in REALLY high temps, or a high elevation. I put it in once in Iowa when 89 was the same price as 87.

 

Some of the people who are trying to use a Corolla as a performance car might want to try 89 pump and a dyno to see if it makes a difference. The only problem is, the ECU doesn't magically change in just a few moments. They tend to figure out the car runs and slowly makes adjustments. Usually unplugging the battery and resetting the ECU will change it quickly tho. If I were trying to get a few more HP out of my Corolla, I'd try 89 pump over any expensive bolt ons.

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Good Point, gvr4evr!!!!

 

I know that the 1zzfe engine has a very high compression ratio of 10:1, which, in the olden days, whould probably called for at least 89 octane gas, if not 93 octane! Of course that was without any kind of systems (ECM) that could monitor and adjust the engine to compensate for different engine conditions. I don't know about the other generation of Corolla engines, what their compression ratios are, but, when you start to hit 9.5 or 10:1, premium gas could potentially help.

 

The main thing to remember is that Corollas are mainly economy cars and as such, will probably never be driven in such a way to require higher octane fuel. But, for performance-minded people, I'm sure a tankful of mid-grade, or even premium couldn't hurt and might even pull a little extra power out of the Corolla's engine, so point taken.

 

For me, personally, I will continue to run 87 octane in my Corolla and drive it as an economy car. At 3 dollars plus a gallon for gas, I can't justify spending the extra money and driving the car in a way that it would use MORE gas than it normally would, but to each his own......

 

timkedz

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I am converting my car to run on water.

By subjecting the water to radio waves it makes it combustible and fuel efficiency is a lot cheaper.

If anyone else would like to do the same, let me know. Salt water gives it more power than fresh water.

The oil companies don't know about it yet, but if they do find out - they might offer to buy me out.

can you imagine when the secret gets out and people no longer need a petroleum based fuel?

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I am converting my car to run on water.

By subjecting the water to radio waves it makes it combustible and fuel efficiency is a lot cheaper.

If anyone else would like to do the same, let me know. Salt water gives it more power than fresh water.

The oil companies don't know about it yet, but if they do find out - they might offer to buy me out.

can you imagine when the secret gets out and people no longer need a petroleum based fuel?

 

 

Congrats, you win the dumbest post ever award!!!!

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well, I totally agree with you but there is a difference I have seen on my 98 (8th gen) Corolla. its not performance but visit to a gas station.

 

the way I drive:

when I fill up 87 octane, the gas tank emptys withing 2 weeks

and if I fill up 89 octane, the gas last about 3 weeks or so.

 

so I chose to do 89 since it gives me almost 150% of 87 for couple of bucks more.

 

I'm trying to run my 1988 Corolla on 91 octane to test this. It took a few days for the engine to get used to the 91, since I normally run 87 octane. However, the owners manual clearly says that "87 octane or higher" can be used.

 

also... when you guys fill up your corolla, how many gallon does it usually take in. Mine takes in about 10-11 gallons, 11 gallons when "fill gas damit" light is blinking..

but the capacity acording to specifications suppose to be 13 gallons or something.???

 

My "fill gas" light blinks at about 10 gallons or thereabouts, but like yours, mine has a 13.2 gallon tank. Last time I filled up, 9.928 gallons when the "E" light came on (but then it went off. Hmmm?) It has been as high as 11 gallons. Perhaps the sensor is bad . . .

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1zzfe only has one timing map which is optimized for emissions and to burn 87 octane fuel, the knock sensor is a safeguard in the event that knock does occur the pcm can adjust timing to compensate and keep the engine running safely.

 

I realize that this is an old post, but does anyone know where I can find parameter info for a 1988 4AFE engine? I've been testing 91 octane in an 1988 Corolla SR5 4AFE engine; according to the shop manual, compression ratio is 9.5:1. Does this compression seem okay for 91 octane? Prior to this, I was using 87 octane. But the users manual does say, "87 octane or higher" (my emphasis). Timing advance is 13 BTDC now, was 10. Idle is high 600's - low 700's (according to manual should be 800 -- I am going to check the IAC and throttle body for carbon deposits).

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Back in the old days (carburated) - compression ratio and octane were as followed:

 

6:1 - 83 octane

7:1 - 87 octane

8:1 - 92 octane

9:1 - 96 octane

10:1 - 100 octane

11:1 - 104 octane

12:1 - 108 octane

 

But now with modern fuel injection, computer control, and advanced knock sensors - you can drive the octane requirements down pretty far. The 1ZZFE is a good example - 10:1 compression ratio - 87 octane - 5 degrees BTDC (w/ VVT-i it is 5-48 degrees BTDC). My 2ZZGE with 11.5:1 CR runs on 91 octane just fine. Even so - I like to run 93 or higher in the Matrix and at least 89 on the Corolla - as they both get slightly better fuel economy and no pinging at all, even with heavy engine loads. Cost actually works out almost even at the end (I get about 9-11% better fuel economy, but spend about 10% more on the better stuff = almost no net cost savings or loss, but at least the engines are happy).

 

Sounds like your 4AFE is just fine - it is not unusal for an older engine or one with lots of miles to run pretty decent on higher octane. The carbon deposits are effectively raising your CR slightly and creating "hot spots" that could cause detonation. That's why the owner's manual is worded in that manner - 87 octane or higher - best way is to fill the tank with increasing grades of octane until you find one that doesn't ping under normal driving conditions. Then that should be your minimum octane requirement for your car. Might need to "decarbonize" the combustion chambers - but that could potentially cause more problems than good, so be careful.

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Sounds like your 4AFE is just fine - it is not unusal for an older engine or one with lots of miles to run pretty decent on higher octane. The carbon deposits are effectively raising your CR slightly and creating "hot spots" that could cause detonation. That's why the owner's manual is worded in that manner - 87 octane or higher - best way is to fill the tank with increasing grades of octane until you find one that doesn't ping under normal driving conditions.

You brought up another point, I am always confused by the differences between "pinging" and "knocking" I'm not sure if I have ever heard these sounds or what they really sound like; I wish there was some website with an audio file of pinging versus knocking. I do know that when I start up, I hear a high-pitched flapping noise coming from the area of the intake manifold/EGR valve: it's quite loud at first, and drowns out the lower-toned valve sound coming from the valve covers. Once the car gets warmed up, then the sharp high-pitched flappy sound diminishes but never fully goes away. I haven't taken apart the air hose to check the throttle body/IAC valve, but I suspect this may be related to that. Or does anyone have other ideas? I'm still a noob at DIY mechanics.

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Hmm interesting. Well pinging could be best described as a tinkle sound - almost like breaking glass. Higher pitched flapping, fluttering sounds - if it sounds like coughing and the engine seems to surge a bit (power acts like it is being turned on and off) sounds a lot more like a misfire on one or more cylinders. If you are running a higher octane and still getting the noise - then I would probably rule out pinging. Could just need a to clean the intake side or adjust the valves on the car - that could also cause some high pitched noises to pop out the intake side.

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Sounds like your 4AFE is just fine - it is not unusal for an older engine or one with lots of miles to run pretty decent on higher octane. The carbon deposits are effectively raising your CR slightly and creating "hot spots" that could cause detonation. That's why the owner's manual is worded in that manner - 87 octane or higher - best way is to fill the tank with increasing grades of octane until you find one that doesn't ping under normal driving conditions.

You brought up another point, I am always confused by the differences between "pinging" and "knocking" I'm not sure if I have ever heard these sounds or what they really sound like; I wish there was some website with an audio file of pinging versus knocking. I do know that when I start up, I hear a high-pitched flapping noise coming from the area of the intake manifold/EGR valve: it's quite loud at first, and drowns out the lower-toned valve sound coming from the valve covers. Once the car gets warmed up, then the sharp high-pitched flappy sound diminishes but never fully goes away. I haven't taken apart the air hose to check the throttle body/IAC valve, but I suspect this may be related to that. Or does anyone have other ideas? I'm still a noob at DIY mechanics.

 

 

Pinging and knocking are the same thing. What you are describing sort of sound like lifting tick to me. You could try to clean it up with some sea foam. Put 1/3 of a bottle in your crank case before you change your oil. Just read the direction. Pretty decent stuff.

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I just got back from Baja, and the Corolla ran fine. I've been running 91 octane for the past 1000 miles, and despite a modest increase in horsepower on hills, there has been no change in fuel economy. Still get 24 mpg in pure city driving, 30-31 on the highway which was what I was getting before (I wish there was some way to turn off the 4WD when I don't need it). Thus, the two week experiment to test whether or not premium fuel increases gas mileage has shown that it, in my car at least, there is no appreciable benefit from using 91 octane over 87 octane, but my wallet sure is a lot thinner. So, I'll probably switch back to 87 octane.

 

Pinging and knocking are the same thing. What you are describing sort of sound like lifting tick to me. You could try to clean it up with some sea foam. Put 1/3 of a bottle in your crank case before you change your oil. Just read the direction. Pretty decent stuff.

 

I assume after putting in the Sea Foam, I should run the engine for a bit (but not drive it anywhere), to circulate the Sea Foam?

 

Lastly, does anyone know a way to remove spark plugs that seem stuck? I wanted to change the plugs before driving down; it's been about 2 years since I last changed them. But I can't seem to get them to budge. I suppose I could apply more torque, but I don't want to break them off in their socket. Can I apply some sort of "Liquid Wrench" to them, or is this harmful to do since whatever I add will run into the cylinder head/ignition chamber? Perhaps use some petroleum-based loosener since that will be simply combusted when the engine is fired up after replacement of the spark plugs?

Edited by datsa

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