93 octane

[justinj]

I am buying a 1995 polo green convertible on Monday from a local
lady, she has taken great care of it, only 60k miles. When I test drove it it was low on gas and she asked me to fill it up. I did and when I got back I mentioned super unleaded is pretty high she mentioned that for the last two years since she owned it she has only put regular in it. Since the comp. ratio is 10:5:1 has she harmed the engine in any way with the 87 octane, it did not ping or hesitate. Thanks.

 

[Tims93]

Don't worry, the car probably didn't preform as well as it could but she probably didn't care. Normal driving with less than 93 shouldn't harm the engine.

 

[92ghost]

From what I have heard and read about the LT1 the answer is NO she did not hurt the engine. With the onboard computer the timing will be advanced or retarded according to various input from knock sensors, oxygen sensors and a whole slew of others to keep the engine from self distructing. However,chances are the car did not run smoothly, and will be down on power with anything less than 93 octain. Once the new higher octan gas is introduced it does take a while for the ECM to re-learn. In other words I believe the on board compter makes incrimental steps as it recalibrates the engine on new fuel. It may take 1 or 2 tanks of the 93 octain for all the adjustments to take place. Keep in mind this is my opinion and I would like C4C5 specialist or someone of that caliber to reply to varify.

Wayne

 

[WhalePirot]

You can reset the 'adjustments' made by the ECM by unplugging power to it for at least 10 seconds. The ECM will detune the engine for the lower octane and barring any knocking, which I doubt happened, I see no issues. The ECM continues to learn (adjust) whenever the engine is running. This reset allowed my car to pass SMOG tests, on more than one visit, after it had failed. My power wire to the ECM is orange, with a disconnect plug, found very near the battery. Simple.

I would, however, look the car over carefully as, if money was an issue, other maintenance issues may arise. I have had excellent luck buying used cars after looking for hints, such as matching spare tire (with the four running tires). Someone who has the bucks to keep a car thusly, has the bucks to maintain the rest.

While the spare technique won't work with all Corvettes, the eye tells through careful observation of cleanliness and originality; not speaking of a shop 'dress-up'.

 

[justinj]

thanks for the input

 

[Skant]

I'd be suspicious that the car really was well taken care of. It doesn't seem to me like someone who would run a corvette on regular gas would be the type to change the oil regularly, grease the suspension fittings, etc. She might have decided to go with cheaper dino oil, too (which really would hurt the engine).

I'd check it all out very carefully.

- Skant

 

[warren s]

Low octane gas wont hurt it, if she gave it more than 1/4 throttle it would just retard the timing.

You dont have to disconnect the computer on the 95, it will adjust on the fly as it finds better octane and does not sense knock as the timing is advanced.

SKANT had a very good point about the oil, i know its not what you asked but its somthing to think about.

 

[justinj]

she had it changed at the local lube shop with mobil 1 she took care of the car she is a 60 yr old lady with too much money and not a lot of common sense. She only drove the car 3000 miles in 2 yrs.

 

[robert kirk]

sounds like a nice car justin. Good luck with it glad you could join us. Give us more details after you pick it up. Lots of great info on this site. Lot of help here with all the little problems that arise from owning a corvette. :cool robert

 

[oldace84]

93 Octane, where?
I live in Southern CA. Orange County.
93...WHERE.
thanks
tony

 

[atmmac]

Just buy it! Im sure its fine!

 

[WhalePirot]

93 Octane is not sold anywhere I know of in So.Calif., but IS, back east. I enviously saw it in So. Carolina while filling a rental car. My car also ran a lot better on un-'oxygenated' fuel. Hell, my sister learned that one with a mini-van!

The ECM on a stock '84 adjusts 'on the fly' as any other ECM will. It may learn some things that degrade emissions, especially on a modified engine. I have BEEN THERE, DONE THAT, with a REAL car and have educated a few smog technicians along the way. Unpowering the ECM is simple and quick and MAY help you pass without spending hundreds with an 'experienced' mechanic.

My Corvette has been spoiled as well as any of yours and I ran regular gasoline from time to time. The ONLY difference was slightly better acceleration with the premium. I did find that ARCO brand gasoline corroded my throttle bodies. Few mechanics were smart enough to know of it, but one explained that the methane, versus the ethane that most companies use as an additive, is corrosive. I now consider ARCO to be an emergency source of fuel on all my cars.

I also ran synthetics in every oiled reservoir. These super fluids, as some would have you believe, did nothing to save my #7 main bearing nor my rear end from 'early' failure, despite my changing it, plus filters, as appropo, more often than called for.

I use my cash more wisely now by running the lowly 'dino' oils with frequent changes, just as car guys have for decades with excellent result and with superior component life. Let's not re-open that debate for the umpteenth time!