what kind of gas do you use?

[howdeyjake]

hey guys, i know this is a stupid question but i just got my 1995 eclipse gs-t and it ran fine when i got it but now it is losing power and running pretty crappy. i put premium in and wasnt sure if i am using the wrong kind gas and that is the reason it was running bad. so i ask you....do what kind of gas do you use???? premium, the middle one, or regular unleaded

 

[v2ner]

WTF $7/ gallon for 100 octane? i pay $3.99/ gallon for 110 octane.

 

[Mist3r Spool]

That's northern California for ya...

 

[Fayt]

I used 87 octane in my car, runs fine and I actually saw no drop in gas mileage; power is another story. I could tell the car is running slower on 87. But, I wasnt racing it at all at that time, just daily driving it, still stock. Now it's in the shop, but once I get it back I have some parts to put on, and then strickly Shell V-Power for it

 

[Deadly BlaZe]

I used 87 octane in my car, runs fine and I actually saw no drop in gas mileage; power is another story. I could tell the car is running slower on 87. But, I wasnt racing it at all at that time, just daily driving it, still stock. Now it's in the shop, but once I get it back I have some parts to put on, and then strickly Shell V-Power for it

i've been using 87 ever since i've driven the car for a year and had absolutely no problems engine-wise. I put in premium about every once a month just incase. i've never felt an increase in power though.

 

[dr1665]

I don't understand why people put the highest octane in when mod wise its clearly a waste.

Highest octane you need is whatever keeps it from detonating early, any higher is a waste of money.

Pretty much accurate. Unless your owners manual specifies premium, you have a turbo engine (which would specify such), or higher compression/advanced timing/modified engine, there is no need to run a higher octane than is recommended by the manufacturer. If you drive a stock NT and you use anything more than 87 octane, you're just wasting your money and fooling yourself if you think you're getting better performance out of it.

 

[xveganxcowboyx]

Pretty much accurate. Unless your owners manual specifies premium, you have a turbo engine (which would specify such), or higher compression/advanced timing/modified engine, there is no need to run a higher octane than is recommended by the manufacturer. If you drive a stock NT and you use anything more than 87 octane, you're just wasting your money and fooling yourself if you think you're getting better performance out of it.

Turbo (1G at least) specifies 91 and sais it *can* run ok on 87. Same scenario. Anything above on a stock engine is a waste. If you knock on a stock turbo engine with 91 something is wrong.

 

[gsx951]

I don't understand why people put the highest octane in when mod wise its clearly a waste.

Highest octane you need is whatever keeps it from detonating early, any higher is a waste of money.

That's because you are a N/T guy. Our ECU will advance timing until it hears knock.
20* of advance at 25 psi on Sunoco 94 rules....

 

[gsx951]

Turbo (1G at least) specifies 91 and sais it *can* run ok on 87. Same scenario. Anything above on a stock engine is a waste. If you knock on a stock turbo engine with 91 something is wrong.

That's right, because the ECU will reward you for putting in lower octane by retarding timing to protect the motor from knock. The ECU "senses" fuel octane rating via the knock sensor and will advance or retard accordingly.

For those who've reported no difference, try resetting your ecu. DSMLink is set up to reset octane at each start up, which is very cool.

 

[Deadly BlaZe]

Turbo (1G at least) specifies 91 and sais it *can* run ok on 87. Same scenario. Anything above on a stock engine is a waste. If you knock on a stock turbo engine with 91 something is wrong.

on 1ga's on the fuel tank door, i'm pretty sure it says unleaded fuel only. I know on 1gb's and 2g's it says premium unleaded only.

 

[xveganxcowboyx]

That's right, because the ECU will reward you for putting in lower octane by retarding timing to protect the motor from knock. The ECU "senses" fuel octane rating via the knock sensor and will advance or retard accordingly.

Hence the stars around CAN.

on 1ga's on the fuel tank door, i'm pretty sure it says unleaded fuel only. I know on 1gb's and 2g's it says premium unleaded only.

The manual specifies 91. The fuel tank door is an "idiot reminder."

 

[gsx951]

Anything above on a stock engine is a waste. If you knock on a stock turbo engine with 91 something is wrong.

This is what I took exception to, as it is dead wrong.
It would only be a correct statement if the vehicle lacked a knock sensor and did not make timing adjustments relative to fuel.

Higher octane combined with an advanced ignition equals greater cylinder pressures.

 

[joesansone17]

93 octane

 

[xveganxcowboyx]

This is what I took exception to, as it is dead wrong.
It would only be a correct statement if the vehicle lacked a knock sensor and did not make timing adjustments relative to fuel.

Higher octane combined with an advanced ignition equals greater cylinder pressures.

How do you figure that? The gas itself certainly doesn't increase cylinder pressure. Does the ecu advance timing as far as it possibly can without hearing knock? I highly doubt it, because it would lower mileage and increase emissions.

 

[gsx951]

How do you figure that? The gas itself certainly doesn't increase cylinder pressure. Does the ecu advance timing as far as it possibly can without hearing knock? I highly doubt it, because it would lower mileage and increase emissions.

Read your manual newbie.

 

[xveganxcowboyx]

Read your manual newbie.

How about you not go calling people unfounded names and correct me. I'm perfectly open to learning something new.

And I have read nearly every bit of the manual, but it's entirely possible I missed something. So please, explain your rationale instead of insulting me.

 

[gsx951]

How about you not go calling people unfounded names and correct me. I'm perfectly open to learning something new.

And I have read nearly every bit of the manual, but it's entirely possible I missed something. So please, explain your rationale instead of insulting me.

Newbie is not an insult, it's what you are.
On the back of the block there is a piezo sensor that sends a signal to the ECU when knock is detected. The ECU makes decisions on timing based partly on input from this sensor. I can't recall the maximum advance but from that, timing is removed based on fuel octane or lack there of.
When you get yourself a logger , you'll be able to watch this knock/timing relationship and use it to tune.

 

[xveganxcowboyx]

Newbie is not an insult, it's what you are.
On the back of the block there is a piezo sensor that sends a signal to the ECU when knock is detected. The ECU makes decisions on timing based partly on input from this sensor. I can't recall the maximum advance but from that, timing is removed based on fuel octane or lack there of.
When you get yourself a logger , you'll be able to watch this knock/timing relationship and use it to tune.

Ok, I get that completely. What i was saying was that there WAS a maximum timing advance (better term than I used). My point was that the car should be able to run at max timing on the recommended fuel. It's not as if it will just keep on advancing it on it's own just because you added higher octane fuel. Of course if you run advanced timing by choice that's a whole nother story.

You haven't said ANYTHING new yet.

And watch who you're calling Newbie. While I don't know everything I've been working on cares for years. I'm not an idiot so don't talk to me like one.


So unless you're going to tell me that timing will be advanced further by using higher octane (maybe it will, but I doubt it) My point still stands.

And can you adress this 'higher octane gives higher cylinder pressure' thing you were talking about, because my tiny newbie brain doesn't get it.

 

[gsx951]

And watch who you're calling Newbie. While I don't know everything I've been working on cares for years. I'm not an idiot so don't talk to me like one.

Uh, yeah... As far as the Newbie comment goes, I'm 44, I was driving your car when It was a new model. The things you are into now, I experienced 15 years ago. Yes, I've also been working on cars for years; since 1975.
Newbie doesn't mean you're stupid, just new and inexperienced. You may wish to relax and not be so thin skined.

 

[Tweaker_911]

Yeah, what he said


I use AGIP or ESSO Senza Pimpa, the crap they sell over here doesn't come with an Octane Rating, but it does sell for $4.00 USD a liter, that's right a liter !!!! You do the math on how much you'd pay to fill'r-up, makes me

 

[xveganxcowboyx]

Uh, yeah... As far as the Newbie comment goes, I'm 44, I was driving your car when It was a new model. The things you are into now, I experienced 15 years ago. Yes, I've also been working on cars for years; since 1975.
Newbie doesn't mean you're stupid, just new and inexperienced. You may wish to relax and not be so thin skined.

Do you plan on discussing cars or just my age? Feel free to back up what you said. I'm totally open to learning something new, but as it stands you've made a claim and failed to back it up. I don't care if you're 90. If you can't tell me why putting 93 octane in your car 'increases cylinder pressure' then you don't know what you're talking about. So stop trying to change the subject. You gave advice. Either it's good advice or bad advice. So far it's looking bad.

 

[gsx951]

Higher octane allows for more advance (The ECU does not retard time due to knock). More advance allows for more complete combustion as engine speed increases.
Without advancing time, the fuel does not have enough time to complete the burn and cylinder pressure is reduced.
If this were not true, then the inverse would also not be true, that is that running 87 octane will have you down on power due to timing being rolled off but we all know that running 87 octane does result in a loss of power.
Your motor does this automatically via the knock sensor and ECU.
Ok?

 

[xveganxcowboyx]

You still have not answered my question. Will the ecu advance timing further with higher octane? I would think that the recommended octane would yield maximum advance. So, if I were to put in 93 instead of 91 would my ecu advance timing further?

So you're saying knock has nothing to do with timing? And if so, why do you then say it judge adjusts timing via the knock sensor? Why is phantom knock causing my timing to be pulled then? Or am I totally wrong there too?


Of course better combustion, advanced timing, more boost, etc wil result in higher pressure and thus more power. The question is whether higher than recommended octane on a stock engine will do this.

 

[gsx951]

Higher octane allows for more advance (The ECU does not retard time due to knock).

Pehaps I did not phrase this correctly. The ECU does not retard time due to knock because gasoline with a higher octane rating has been used

The ECU will continually advance time to a predetermined maximum that is set in the ECU code until it hears knock.
(Look for post from Cali guys who are moaning over the 91 they have to run.)
What that value is escapes my memory at this time and I'm certain the figure is different for you than I because the 1G advance is much more aggresive.
Do you have a PDA or logger of any kind?

The third generation lifter will make your phantom knock go away, there used to be a sticky with the vendor info here.

 

[xveganxcowboyx]

I'm still not sure what you mean about knock. The ecu should retard timing any time it senses knock. The gas does not come into play, accept that higher octane takes more to detonate.

I'm not sure what the 1G max timing advance is either. My only point is that I *think* it should be able to reach it with recommended octane rating. IE the manual specifies 91 octane for optimum performance so the engine should be able to reach maximum timing advance on 91 octane. Otherwise they would have lower the max timing advance or raised the recomended octane rating. Basically, a proper running stock engine should run without retarded timing on the recomended gas. Any more is unnecessary. Of course age and maintenance play into how well the engine runs...


I'm not too worried about my PK. It's paired with gimpy settings from boost leaks (well, only one now that I've fixed the others. Injector seals coming wednesday ) Once that's done I'll see how it runs. Apparently the rockers get scuzzy so I'll clean them with some tranny fluid or sea foam. If that fails I'll move on to the 3G lifters. I don't remember the best vendor, but apparently someone sells them for $8 a piece.

No logger yet. I was planning on getting DSM link, but my laptop is on the fritz. I'll probably pick up a new palm and logging cable soon. Before I start modding much anyway. A logger should be plenty for me anyway as my long term goals are only about 250AWHP.


*edit* I should mention I'm stuck with shitty 91 octane too. We have 85 (what EVERYBODY fills up with ) 87/88 and 91. I miss MN where 93 was easy to find and I could get 91 as mid-grade. I'm going to have to mix gas just to run higher boost

 

[daren_p]

Its always Sunoco Ultra 94 for me