octane

[pascofan92]

For the longest time i've been consistant with fuel, putting 89 premium in my tank.last night at the station the numbers were all re arranged like 87,93,89.natually i went for the middle and put 93 in my tank, 3 gal. worth!This may be a dumb question but, will this harm my car by running rich like this with 89 still in the tank?-Alaric
Red
1994 ATX

 

[twr]

Not a problem, you can mix grades of gas all day long. Octane does not effect how rich or lean your car will run.

 

[Black '93]

If I were you, I would only put 93 octane in the SHO. 89 is okay, but never 87.

 

[qiksho]

If I were you, I would only put 93 octane in the SHO. 89 is okay, but never 87.

Why not 87? Many on this forum run 87 on a regular basis. There have been numerous threads discussing this topic.

 

[projectSHO89]

If I were you, I would only put 93 octane in the SHO. 89 is okay, but never 87.

You can't be serious.

All of my SHOs have been fed a steady diet of 87 octane during all of the time I've owned them.

I would recommend educating yourself as to what octane actually is before makeing such a recommendation.

Steve

 

[Black '93]

You can't be serious.

All of my SHOs have been fed a steady diet of 87 octane during all of the time I've owned them.

I would recommend educating yourself as to what octane actually is before makeing such a recommendation.

Steve

I said "IF I WERE YOU I WOULD RUN 93. Maybe 89, but never 87." That means I never run 87 octane. Because that's what I choose to run, and no it's not a waste of money. I have read most of the threads on the subject too so I am aware of that also. I suggest you educate yourself on the fact that the words "if I were you" are totally different then "you absolutely must"... Wow! you know what octane ratings mean? You must be the smartest guy ever!!!

 

[noSHO4u]

Oh it's on, it's definitely on!
DING! DING!
Round 2
FIGHT!

 

[pascofan92]

Alls i wanted was feed back on a subject!plz don't bash each other over it! twr pointed me in the right direction and i talked to some mechanics.Our high performance SHO engines have a high compression ratio.So 87 or 89 would work well in our engines.But yamaha and ford reccomends 89 which is sensible and in -the -middle.93 is even better for our engines thus giving the combustion ratios satisfaction and optimum performance.Thanks for the help.I'll stick to 89.-alaric 1994 red atx

 

[1slickRED89]

as long as the knock sensor half works you'll be OK, but if your knock sensor is flaky and you disconnect the battery (reset the keep alive memory), you may get a little knock. and little spark knock never-hurt-no-one.

That said, I run only sunoco 94 in my 94 ATX and am actively looking for 96+ at the pump. I do have a 'special needs' Taurus SHO however.

 

[1993MTXSHO]

running premium, 93 will probably give your sho a little more power because it will be able to change the timing a little more, but as long as its not pinging your fine running 89, or even 87 for that matter, it will usually jsut yield a little less hp. Sometimes depending on the car running premium will give you better gas milage and it almost balences off in price so you get more performance for the same price. I had theis with my truck i ran 87 and then started running 93 with a programmer and gained 2mpg. Im not sure how this will work with stop programming however.

 

[SHOZ123]

From what I have seen premium is only an advantage when air temps get above 90F. Assuming the timing tables provide the max timing, above 90F the IAT will pull timing, then the max timing will push it to the point the KS start pulling timing out. So a higher octane will allow you to maintain the higher timing that you would normally have at temps below 90F.

If the engine has other issues that will pull timing then that's another story.

It's interesting to be able to data log the timing source. This really tells the story. As far as OBDII it is this but I would think the OBDI is not that much different.

Spark Source Values:

0 Crank or under speed
1 Base
2 Borderline
3 Torque control
4 Pre-ignition
6 Stabilized low load
7 Cold engine low load
8 Idle feedback at minimum clip
9 Idle feedback
10 Spark set by on-demand self-test
15 Output State Control
16 Foreground Spark Borderline Clip
18 Closed-Throttle Deceleration Spark

Then you have to see what the IAT or ECT multiplies do to these sources. The ECT doesn't have much of an effect until the coolant temp is sky high. But the IAT comes into play much earlier. This is also why the Hot Air Intakes suck so much.

 

[1slickRED89]

It's interesting to be able to data log the timing source. This really tells the story. As far as OBDII it is this but I would think the OBDI is not that much different.

have you logged spark timing with high and low octane gasoline? that would be the real test, assuming you do a few tanks of each to make sure adjustments to the KAM are in effect and reset the EEC between fuels. I may do that sometime.

 

[SHOZ123]

Yes I've data logged 100s of hours on 87,89,92 octane. FWIW the 87 is straight gas the other two are 10% ethanol.
When it's cool out, say 60F it makes no difference. As the temps rise the KS will start to pull timing. At 90F the timing is pulled due to IAT input. This could be changed but why?

This is at WOT too as part throttle is a moot issue, unless you have detonation.

As far as the KAM this only affects idle speed and fuel trims from what I have seen. The SCT software does not give me complete in depth tweaking on the V8 unlike the TwEECer will do on the V6.

 

[Mr Anonymous]

I said "IF I WERE YOU I WOULD RUN 93. Maybe 89, but never 87." That means I never run 87 octane. Because that's what I choose to run, and no it's not a waste of money. I have read most of the threads on the subject too so I am aware of that also. I suggest you educate yourself on the fact that the words "if I were you" are totally different then "you absolutely must"... Wow! you know what octane ratings mean? You must be the smartest guy ever!!!

Yeah, if you want to keep using this forum, you'll need to put that attitude away right now or risk getting run over by the ban bus.

Aside from illustrating your own ignorance on the subject, those of us that were driving SHO's when you were still in grade school have knowledge and experience with regard to octane ratings and what works best in the SHO that you're sorely lacking. If you want to swallow the marketing hype of the oil companies that's certainly your perogative, but don't come here and start e-thug arguments attacking other members -- especially when you gave such asinine advice as "never 87."

You don't know shit.

 

[Kairoff]

I get some rattle when the car is pulling a load such as going up a hill and when the engine is hot. Changing to 93 Octane does not help. Codes are all 111 on a 93 ATX. Anyone got a clue where to look next?

 

[SHOZ123]

Go to a colder range copper spark plug. Motorcraft AWSF22C available at www.rockauto.com will do nicely.

 

[Black '93]

Yeah, if you want to keep using this forum, you'll need to put that attitude away right now or risk getting run over by the ban bus.

Aside from illustrating your own ignorance on the subject, those of us that were driving SHO's when you were still in grade school have knowledge and experience with regard to octane ratings and what works best in the SHO that you're sorely lacking. If you want to swallow the marketing hype of the oil companies that's certainly your perogative, but don't come here and start e-thug arguments attacking other members -- especially when you gave such asinine advice as "never 87."

You don't know shit.

Well since your the moderator I'll stop but first..............................

I know what works best in my car. My car runs horrible on 87 and decent on 89. It runs ABSOLUTLEY PERFECT on '93...Hmmmmm. That is why I NEVER, ever run 87 octane. In my car it does matter, and if YOU drove it with both 87 and 93 you would agree. If you think that I'm swallowing market hype, you're far wrong..... Actually I know exactly what I'm talking about and I am not some punk kid so have some respect. Just because you have the power to ban doesn't mean you have to threaten me because of my disagreement. E-thug? Dude, now that is funny! If you ban me over this-that is asinine! I guess it was aimed at projectsho since he basically said I was uneducated. The post you just wrote about me was far more abusive than the on I wrote anyways! Now just because some of you run 87 with absolutely no probs doesn't mean you have to be a cop about it.. And I can drop the attitude if you quit trying to make me look stupid for being a little sarcastic. This whole octane thing is a very touchy subject!
I seriously wouldn't doubt you guys get better 87 in Texas than we do in the Great Lakes area anyways. Maybe it's the weather here too.

Oh, and I do know shit. I know you!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

just kidding, but that would have been pretty funny if I were serious huh?

 

[sho_me92]

oh Snap!!

 

[RICHARD ROWLEY]

I Have Tested Both 87 And 90 Plus And 87 Gave Poor Gas Mileage. Ford Recomend Premium For A Reason.

 

[schwagman85]

i wouldnt run anything but sunoco ultra 94. i mean it just money, they make more of it every day