last night when i went to the gas station to fill up my car i thought why not put 94 octane and try it out how it feels cuz i havnt put high octane since i cant even remember its been a long time tho....so anyways after i filled up the car and drove the car about 5 miles, i felt that my car is suddenly quite and more responsive i mean REALLY RESPONSIVE....even tho i have a big *** noisy muffler on the car even that was quiter than before....so my question is that should i use high octane all the time? or it doesnt matter....cuz i know high octane is for high compression engines but how about ours? and which fuel is recommended for our cars?

 

owners manual states you can use 87.
but for maximum performance 92 is recondmended.

some people say it's a waste to use premium.
but i seem to get better mpgs with premium plus i use it becuase i drive her hard most the time, not to mention i have the timing advanced to 20-22*

 

u r not suppose to advance ur timing that much...its bad for ur engine?

 

well i don't hear any knocking.
but now that i think about it.
i did retard it a bit reson being i used bp and it would knock on take off only...

 

causes pre-detonation if you use low-octane fuel.

you have a VE so you especially should use premium. VG is 9:1... ve is 10:1 so the knock sensor will muddy up your responsiveness on low-octane gas.

 

i have had 2 maximas a 99 and a 00 with both cars after switching to 93 insted of 87 my car responded better and befor it used to make weird noises with 87. so i stick with 93

 

wait burhangondal you have an se.
your pic looks like a gxe(the grille).
hell yea homey you should be using premium, my ve was fuged because the previous owner did'nt take heed to the premium fuel recondmended.

 

Explain please?..................

 

well my first 3rd gen was a ve auto.
she had a terrible miss and was spark knocking like crazy.
and columbianmax was dertermined to help me figure out what was wrong.

knock sensor mod, replaced few injectors, coil.
her missfire kinda improved. did a compression test: #5 had 50psi.
did'nt change when we added oil to the cylinder too.

there's two possibilities as to why this happened.
there's been a couple posts sayin if you drive a ve/vg with a non-firing injector it's bad for that cylinder.

and you have the ones where they use cheap 87 gas, and drive the car hard.

i think on the ve both of em...

 

oil not helping = burned valve and i know someone was saying that on a EFI non-direct injection, the fuel helps cool off the intake valves

 

Sorry - but cant see how you possibly could blame the wrong/too low octane fuel for these at all.

If the motor is properly tuned and the ECU,MAF,O2 and KS is working you simply cannot cause those miseries - irrespective of commercial fuel octane used.

............. and a burned intake valve!? ................. go on - pull the other one please .................... that vehicle would have sounded like a Gatling gun going down the street with lots of nice intake spares and flames getting distributed along the road if something like that happened

 

ya man i have VE and GXE both...but i drive VE the one in my profile pic...GXE needs some work and is parked at my skool garage...and for grill....i got into an accident an year ago so i couldnt find SE grill and i end up installing GXE grill thats why lol....it is SE YOO...and dyam i will be using high octane fuel now onn....

 

last night when i went to the gas station to fill up my car i thought why not put 94 octane and try it out
I didn't know 94 octane exist! Are you sure you didn't mean 93 octane?

 

[quote=burhangondal;6592872]last night when i went to the gas station to fill up my car i thought why not put 94 octane and try it out

I didn't know 94 octane exist! You sure you didn't mean 93 octane?

 

[quote=CMax03;6593489]ya we have 87 89 91 and 94 here

ya i said 94 lol cuz it is 94

 

yes use premium, people complain about the extra cost, but if you fill up, say, 3 times a month (I only fill up twice though), and it's 20 cents more a gallon, then thats 45(gallons)*20cents=$9 more a month. Is it worth it to you to be running the recommended fuel for your car for only $9 extra a month? I'd say yes.

 

similar story, decided to go to a gas station that is always cheaper than the one right by my house (about a mile difference) the extra time I wasted due to the small lot (and everyone just got off work), I wasted about ten extra minutes to save $.05/gal. I put ten gallons in, so I "saved " $.50.

 

[QUOTE=burhangondal;6593531]87 89 93 here


wrt 'worth it' for higher octane, in some situations your MPG will offset the higher price of premium... ie if you get 10% better mileage and premium is 4% more than regular, you win. where you live, how you drive, and what you drive will all play a part in whether or not your MPG will actually change by using higer octane. For me, it didn't from 89 to 93. For others, it might.

 

there is a post that states if you dive these cars with a bad injector (clogged or does'nt spray) it does something bad to that cylinder.

columbian max was in denial just like you. after we done all of that and got the compression readings it was confermined.
also in the past i had posted that there's like a click/hiss noise.
and brian helped me out with thie issue also.

valve timing was'nt off either....

 

i like my 93

 

[QUOTE=CMax03;6593489]O yeah ... believe it. Depending on emission and region that U live in. ( especially cold ) I used to live in NYC and we had 93 (94 if u went to Sunoco).

I used to run 93 in my GXE in NYC and the response and MPG were great. Tho the owners manual says 87 octane.. consider that that is the MINIMUM requirement.MY current 92 SE requires 91 and above. it even states that on the fuel door. With these fuel prices tho.. i`ve been running 89 and getting away with it.

Another note.. depending on how u care for your engine.. if carbon builds up in your combustion chamber.. it causes compression to go up a lil and can cause detonation ( rattle noise off idle). When that happens .. ya Knock sensor detects that and the ecm does it`s thing to retard timing.

I once ran 100 octane Cam 2 gas in my car ( u guys from queens NYC know where I got that..lol) and it didnt do squat !!! just strong odor from tail pipe. I recently learned that if u go to high an octane .. like example 110-115 racing fuel.. your STREET ENGINES will run like crap. That stuff is made for 11-13:1 compression engines,, similar to a diesel

Hope this helps anyone out....

 

I am not doubting that a valve got burnt at all - its just the statement that it was an intake valve and that its presence should/could be directly related to octane rating doesn't sit well with me at all .......................... So you pulled the heads and mechanically confirmed a burned INTAKE valve or did you just swap the motor and assumed? Even if you got a burnt intake valve - how can you discard the more likely cause of a valve mechanically not seating properly (piece of dirt etc on the seat preventing proper valve closure allowing combusting gas product past/through the open valve)

I have seen the insides of many motors and have seen many burnt valves in about 30 years - and all of them were exhaust valves.

No fuel going into a cylinder because of a funky injector cannot generate power or heat in that cylinder so valves cannot get burnt at all, and leaning out the mixture in a cylinder due to funky injector actually slows the flame propagation so if any valve are to be damaged due to lean mixtures imo it should be the exhaust valve.

I can only repeat what I said before - "If the motor is properly tuned and the ECU,MAF,O2 and KS is working you simply cannot cause those miseries - irrespective of commercial fuel octane used" .................... I am willing to bet that there was a cause of the burnt valve ................ but simple octane rating of fuel it ain't.

 

umm it was a burned EXHAUST valve i never said it was the INTAKE valve.
the hissing/clicking was coming from there...and the weirdest thing is once we found out it was the cylinder head columbian max was wanting to replace it.
his exact words were:

so when do you wanna come over and replace the cylinder head?!
lol.

 

yea i didn't mean to suggest a burned intake valve. i wans't mentioning octane and just meant to say that i heard someone say that if an injector isn't firing there will be no fuel to cool off the backside of the intake valve. i wasn't talking about Stillman's VE specifically.

 

^^for some odd reason i just busted out laughing, because you knew my name.
but i'll be doing a seafoam tomarrow.
all of this carbon build-up and missfires is makin me wonder bout me sXe....

 

umm, its because john used to refer to you as "stillman," rather than "1992maximase30" (and probably still will, whenever he decides to come '***** over here, again)

 

I'm surprised too! Here in CA I've only seen 87 89 91, never a 93 or a 94, could that be because of emission laws here?

 

The octane level sold around you has to do with how close you are to sea level. The higher up you are the less atomospheric pressure there is and therefore the less resistance to igniton you need in your gasoline. If you are nearer to sea-level, or below it (uh-oh), you will need higher octane gas to resist knock. That is the only difference in between gasoline's octane rating, its resistance to ignite under compression, hence the reason a high compression engine needs higher octane gas to avoid pre-detonation. The more atmospheric pressure you have, technically, the more compression you have, which is why higher octane gas is found near sea-level. I may be slightly off on some points, but that is the general idea.

 

how about ppl living aroun beaches and on islands then ...they probably need 100 octane fuel lol....jus kiddin...u might be right

 

Probably, but it doesn't make sense or I should say it doesn't apply here, I live 30min away from the beach and haven't seen a gas station with anything higher than 91 (or maybe never pay attention to it)

It there a chance that might be vice versa? lower octane level at sea level and higher on places over the sea level?

 

Its not bad if you use high octane. If you used low octane like 87, there would be detonation, and that would be bad. Advancing the timing is fine, ONLY if you use high octane.

 

this may be a stupid reason i use premium:
if the injector fires weakly i don't want it doing any damage to that cylinder.
so the premium can mask the issue but prevent it from getting any worse.

 

In response to the posts above, I am honestly not sure why you would have only 91 near the beach. I do know that really high cities such as Denver have relatively low octanes "85, 87, 91". The general rule is that as you go down octane requirements go up. It is possible that your area just doesn't have it for some reason... I live at sea-level and see nothing other than 87,89,93. I noticed a lot because I wanted 91 (what my VG reccomends). I see no need to go higher than what it reccomends, because it can actually hurt performance. Never put premium in a car that requires regular, it is nearly as bad as putting regular in a car that requires premium. It makes the engine work harder to burn the (ignition resisitant) fuel. So basically the principle does hold true. Why you only have 91... that's beyond me.

for more reference, see http://forums.pelicanparts.com/showthread.php?t=416296

 

so you just put in half 89 and half 93 (i know mixes as such.. just wondering if that's what you do)

 

This used to be the case in the past while vehicles didn't have knock sensors and electronic ignitions and fuel injection systems all well integrated - ie - carbs and mechanical distributor with simple contact breaker (points/condenser) with a limited and pre-set ignition advance characteristic.

Since emission standards got way more serious, government/industry decided that there no longer is the real need to have such a huge range of octane ratings avail to cater for modern vehicles since most if not all can cater for just about any reasonable octane rating.

In South Africa, we have till probably as recently as 10 years ago, had fuel ranging from 87 (1376m) to 104 (sea-level) available - Basically the whole availability thing of a wider range of octane fuel has to do with the ability to drive an older motor through the whole country irrespective of hight above sea-level and not having to manually adjust the timing to prevent "ping". Even with an older motor, if you stay at any given elevation, you can choose just about any fuel octane readily available in that area , and then find a suitable timing setting that will keep your motor from "pinging"

 

To be honest I never really thought about mixing. I have experimented in many ways with the octane level. I am very doutbful of the VG's need for premium (as stated in the manual (for maximum performance, use 91+) as the knock sensor doesn't seem to care what gas I put in it (this is assumed because my gas mileage never changes, typically if the knock sensor is doing its thing it affects gas mileage). I used to just suck it up and shell out for the expensive 93, but when my brother bought me 87 gas one day(for driving him to the airport), I didn't notice a difference in anything at all. So in the end I am still very confused. I may try mixing and see what that yields. The VG just seems to be the exception the rule in everything involving different octane gas. Low octane doesn't cause pinging and high octane does not help or hurt performance. So my final opinion is that the vg is happy with 87, unless of course you advance your timing, then it will kick your behind if you don't give it 89+.

To LVR, there is still some difference in octane level in the states, it is not nearly as big as what you said you had in south africa and I think the only reason it exists for the most part (after reading your post) is because of the cost of gas. If a place can get away with the bare minimum octane (typically the cheapest) they are going to do it.

 

It has ntn to do with HIGH cities or SEA LEVEL...cuz on some gas stations here in Canada they have 87,89,91 and 94 and some of them dont have anything up to 91.....and it was bothering me and i jus went to the gas station and asked them and wat they told me is that its all depends on the location and every year we go over the reports and decide if we should add 4th octane which is 94 or no on this gas station...i donoo if hes right or no

 

Those numbers I quoted are from about 10 years ago as I said. Currently we have probably a range of 91 to 95 here at best.

 

Very astute observation that.

Guess you either cant read or simply don't want to think about anything said.

Again:

In the past, with older vehicles and non-integrated engine fuel/ignition management systems, you had a simple timing control system - ie - static plus vacuum and centrifugal. With those constraints you could not automatically cater for air density variations. When using a given fuel octane rating in the motor, if you stayed up at 1400m with its thin air, you needed way more timing advance to get the optimum out of a motor than at sea-level with lots of dense air and the same octane fuel .If you now are a traveler between 1400 and see-level, you are guaranteed to run into pinging long before you reach sea-level ................... and the obvious way around that at the time was to have fuel with a higher octane rating (more resistant to knock/pre-ignition/detonation) available the closer you get to sea-level.

With the advent of integrated engine management systems on modern motors that constantly adjust their fueling and ignition parameters to environmental conditions, that particular need for the availability of a huge range of octane has just about completely been removed.

Gas stations will keep in stock the stuff that are used and sold in their area - its a question of money for them, and they couldn't give a toss about the actual reasons why particular fuel octane ratings are/should be available to prevent damage to the average Joe Blogs' engine that have no clue how/why to tune a motor properly for altitude.

 

lol my bad dude