Lets talk Gas

[JimW]

Ok.

I ran a mini 100km (60 mile test) with my Aurora over the past few days for the purpose of seeing what 89 octane fuel does the the L47 engine.

Well, do yourself a favour...do not use it if you do not have to. The car feels like a V6. I find my car has what I refer to as 3 stage acceleration power. 1st is simple hard acceleration, 2nd thru the power gears the car climb up to 4000RPM and if the car is in 3rd (on the shifter) it holds 3rd for quite a while, then 3rd stage power kicks in, at WOT the transmission automatically overrides the 3rd gear position and the car down shift into 4th, at this point max tq is reached and max HP is being reached.

With any less then 91 octane my car wouldnt go WOT, it held that "2nd stage power" and just wouldnt drop. Acceleration was totally gutless. The knock sensor was retarding my engine timing in an effort to reduce pinging and knocking.

Once I got past the 100km I pulled into the nearest gas station and loaded up with 6 gallons of 91 and a bottle of octane booster. Bare in mind that on Friday I filled up 8 gallons of 89 and it mixed with nearly 12 gallons of 91 already in there....I could still notice a difference.

None of this is proven mechanical fact, only my experiences over the last few days. Do yourself a favour, dont use mid/low grade fuel.

Sure it doesnt help that I need new plugs/wires and a decent tune up...

[omegaic]

1. Knock is bad.
2. Octane booster is useless.
3. Premium gas is good.

[kobalt]

At least the knock sensors did their job!



You could get the performance back by burning off the rest of the gas or for about $4. Toluene or a derivative of is the most common ingredient in octane booster. Unfortunatley a .5L bottle will raise the octane only 3 points in your average fuel tank. This means your ~90 octane mix would become 90.3 octane at best.

10% mix of toluene would raise that to 92 octanes or so. Most folks do not realise but toluene can be purchased at a hardware store (paint section) for about $4/gallon.

[JimW]

I have seen tables set up by my co-admin at BonnevilleClub about toulene, its great to use granted its used properly...not for amateurs.

and yes...I used the booster just for posterity...but I have WOT back now

[Letitroll98]

Good analysis kobalt. Assuming a few approximations in your calculations you are right on. Additionally if you open a bottle of fuel injector cleaner and octane booster from the same company, you will find they are the same fluid, same smell, same viscosity. (Smells and viscosity vary between brands because of whatever snake oil additives each may use). I throw in a bottle of the cheapest stuff from the grocery store every dozen tankfuls or so for preventative on the fuel injectors. (It won't do enough to clean dirty ones, but regular use can keep clean injectors clean) The cheap stuff smells most like pure Toluene (from my paint salesman days in the 70's). I don't pay attention if the label says "Fuel Injector Cleaner" or "Octane Booster".

[JimW]

Not being able to go WOT in a V8 Aurora is very defeating...there is a smug punkass in his Lexus IS300 that managed to stay in front of me last night. He'll get his due shortly

He was in front of me at the light and I just couldnt catch up to get in front of him...its not worth it to put anything but the best gas...

[scottydl]

Jim, you've almost got me convinced. I think I'm willing to spend the extra few bucks per tank for 93 (for awhile anyway), and see what it does compared to the 90 I usually run. If the gas prices keep coming down, that'll be even nicer... I filled up for $1.86/gal today (90), which was a pleasant change.

[SupaStealth]

its hard to find anything but 91 octane for premium back home, i'm goina feel bad for my car when it has to go back to that, heh.

[Marc]

Octane makes a big difference in the 2001 4.0. The 2001
4.0 demo that I drove 4 years ago was running on 89
octane. It didn't knock (the knock sensor took care of
that) but it didn't have the power that it should have had.
I immediately started to use 93 Sunoco ultra in my 2001
4.0 the day I got it. There was a big difference in power
between the demo & my car because of that.
In fact, the 2001 owner's manual says " use premium,
for best performance and when towing".


____________

GM!!! BRING BACK OLDS!!!

[stevensolds]

i always use 93 octane, even if its $2.25 a gallon. and scotty where in the hell do you get it for 1.86? wait, are you in canada and are talking liters?

[kobalt]

Letitroll98 said:

Good analysis kobalt. Assuming a few approximations in your calculations you are right on.

Luckily it is difficult to go wrong with toluene - 1 part toluene 9 parts gasoline will boost octane by ~2. It is safe too - my dad used a 20% mix in his Skoda for 7 or so years during winter (Poland winters are very, very cold and resonable quality fuel was hard to come by in the 80s thanx to the commies) with no adverse effects.

[JimW]

stevensolds said:

i always use 93 octane, even if its $2.25 a gallon. and scotty where in the hell do you get it for 1.86? wait, are you in canada and are talking liters?

Scotty lives in the US, and if we converted to USD here, we'd be paying..hrm

Lets see..any given day 93 octane = 90 cents/L or so, almost 4L in a US Gallon, so $3.60 CDN for a gallon, and the CDN dollar is worth 84 cents US..so 3.60x.84= $3.02 USD per gallon.

You folks dont have anything to complain about...ever.

[stevensolds]

wow.fock. do you get premium or regular jim

[JimW]

Always premium, the first post in this thread talks about my experience with regular.

[dred98]

The best gas I can find around here is 91 octane.
Whatever happened to Sunoco 260 - what octane was that anyway?

[scottydl]

stevensolds said:

i always use 93 octane, even if its $2.25 a gallon. and scotty where in the hell do you get it for 1.86? wait, are you in canada and are talking liters?

Nope, I just watch certain gas stations like a hawk. The price creeps down penny by penny each day, until it shoots back up ~20-25 cents over a few hours. I try to calculate it so I fill up RIGHT when the price is at its lowest. Plus there a a couple stations in town where mid-grade is (1) the same price as regular, and (2) 90 octane instead of 89. That's how I do it.

Now if I switch to 93 premium, my whole routine will have to change.

[SupaStealth]

maybe this will help ya with your search on cheap gas, who knows maybe you'll try out some 93 octane

www.fueleconomy.gov/feg/gasprices/states/index.shtml

[Marc]

dred98 said:

The best gas I can find around here is 91 octane.
Whatever happened to Sunoco 260 - what octane was that anyway?

Sunoco 260 vanished in the early 1970s - a casualty of
the US government's campaign against pollution. This
fuel was rated at either 96 or 97 octane, and the EPA
decided that that was too much lead.


___________

GM!!! BRING BACK OLDS!!!

[Rocketv8]

AGAIN, I HAVE TO AGREE WITH STEVENSOLDS!!!
I WILL ONLY USE 93 OCTANE GAS IN MY AURORA, EVEN IF ITS $2.17 A GALLON, WHICH IS WHAT I JUST PAID FOR IT...THERE IS A DIFFERENCE

[SupaStealth]

heh, i just paid $2.33 the other day, i can't wait to get out of the city and back home, it shold be abot 20-30 cents cheaper a gallon

[stevensolds]

i know i get max power with 93 octane. one time i tried Sunoco Ultra 100 race fuel lol. only put like 3 gallons in and it was 3.94 a gallon.

[Custom88]

you also have to keep in mind guys that it takes your PCM 50+ miles to adapt to a new octane level. If your car is used to running the premium then you put in the regular and midgrade it is going to have the ignition timing set to be running on premium.. not regular. Once the PCM adjusts the fuel tables and timing after the 50 or so miles it takes to re-learn it'll run better but still not totally up to par as premium gas. This is one reason why it's not suggested to run regular 'every once and a while.' Pick a gas brand and octane level and try to stick with it for consistant results. I've done the same test, only with the L67 and for the first 50 or so miles the performance sucked as JIM W stated, but after the 50 miles it started to run much better. I usually run 91 octane but at times I'll run 94 ultra for a few months if prices are staying low.

[stevensolds]

i just stick with 93 then

[gfulton]

I also run nothing but 93 octane in my '99. For those who may be in another country or location in the US where 93 is not available, there is a way to compensate for it, though. There's a parameter in the PCM called "service spark retard" that can retard base timing to compensate for lower octane. I checked it to make sure when I bought my car that it was set to full advance and it was. Here's the data definition from Alldata:"Service Spark Retard. Display shows degrees from 0 to 4. This displays the amount of spark retard in degrees from the base spark timing of 10 deg. BTDC. Service spark retard is used to compensate for poor fuel quality or low octane fuel. It can only be adjusted with a scan tool. If the battery is disconnected the service spark retard steering will reset to zero". I was able to set it with my OTC scan tool, just to check it, but put it back to base timing. May help somebody who can't get good fuel.

[scottydl]

gfulton said:

"Service Spark Retard. Display shows degrees from 0 to 4. This displays the amount of spark retard in degrees from the base spark timing of 10 deg. BTDC. Service spark retard is used to compensate for poor fuel quality or low octane fuel. It can only be adjusted with a scan tool. If the battery is disconnected the service spark retard steering will reset to zero". I was able to set it with my OTC scan tool, just to check it, but put it back to base timing. May help somebody who can't get good fuel.

Great info! My question is, what *should* the setting be under normal circumstances? 0? If one uses lower octane fuel than 93, should we (I) attempt to have the number set differently for maximum performance?

[gfulton]

From what I understand of the "service spark retard" option in the PCM, it would only be used if the car were operated in a country where you couldn't get 92 or 93 octane. Would probably set a DTC, (service engine soon light), if the fuel was so bad that it was always doing a spark retard due to the knock sensor. In that situation, the dealer could set it back from base timing some to prevent the DTC. The service manual gives a scant description of it, and that's just my opinion. It should always be left at "0", or base timing here in the US if you're using the right octane fuel.

[JimW]

Good info indeed,

Just an aside, I gased up (35L top up) at 77.9 cent a L for 91 (67.1 for 87)

Cheapest I have seen gas prices in a helluva long time.

[stevensolds]

I know its only 1.90 for premium here right now. I fill up whenever its at 3 quarters left its so cheap

[JimW]

I recall filling up in Syracuse last summer for 2.35 a gallon IIRC

Economists say the prices per barrel will keep falling...until summer..lol

[SupaStealth]

Woohoo