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1.8T, Cant find 93 fuel anymore in my area, misfiring on bad gas, can I mix 91 and e85?

jimlloyd40

Autocross Champion
Location
Phoenix
Car(s)
2018 SE DSG
It's the type of driving that dictates what temperature heat range the spark plug should be. If you're racing the spark plug needs to be colder to shed heat faster. If you're driving on the street, even driving hard you will not maintain the heat in the plug like in racing. That's why I've always advocated for stock heat range in a street driven car.


https://ngksparkplugs.com/en/resources/understanding-spark-plug-heat-range
 

GTIfan99

Autocross Champion
Location
FL
Am I missing something?

His car ran well on 93 with no ethanol.

If I read correctly, his car didn't like 93 oct with ethanol.

How is adding ethanol to 91 Oct to bring up the oct rating any better than just using 93 oct with ethanol?
 
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tigeo

Autocross Champion
Am I missing something?

His car ran well on 93 with no ethanol.

If I read correctly, how car didn't like 93 oct with ethanol.

How is adding ethanol to 91 Oct to bring up the oct rating any better than just using 93 oct with ethanol?
The bottom line is whatever fuel he is using is causing this and adding some E should help sort it out. There can be a lot of variation in fuel quality so whatever the e-free 93 was worked and whatever the current 93 w/e isn't which is what I have here that causes me issues.
 

GTIfan99

Autocross Champion
Location
FL
The bottom line is whatever fuel he is using is causing this and adding some E should help sort it out. There can be a lot of variation in fuel quality so whatever the e-free 93 was worked and whatever the current 93 w/e isn't which is what I have here that causes me issues.

If your tune is so on the edge that you need a new tune to go from 93 no ethanol to 93 with ethanol, you need a new tune anyways.

And this is exactly why I run a 91 oct tune, even though I have 93 available. I want to drive my car anywhere in the country without having to worry about stuff like this.
 

Dog Dad Wagon

Autocross Champion
Location
Innnnn West Philadelphia...
Car(s)
19 Alltrack 6MT
And this is exactly why I run a 91 oct tune, even though I have 93 available. I want to drive my car anywhere in the country without having to worry about stuff like this.

same. I drive around the country and need to be able to comfortably fuel up wherever I am. Also even running 93 on 93, if you get a bad batch or something, you’re now running 92 or less.

a 91 tune will always advance timing when running 91 or 93, it’s just a matter of how much. Also definitely helps in summer.

now, none of this is relevant to me any longer as I am buying a diesel next week lol. I wish they had grades of diesel. Time to start stocking up on stanadyne
 

tigeo

Autocross Champion
If your tune is so on the edge that you need a new tune to go from 93 no ethanol to 93 with ethanol, you need a new tune anyways.

And this is exactly why I run a 91 oct tune, even though I have 93 available. I want to drive my car anywhere in the country without having to worry about stuff like this.
I wouldn't call his issue the tune being on the edge, but it is sensitive to fuel quality in my experience and we just don't know the differences in the fuel beyond what it's basics are i.e. 93, 93 no e, etc. I've run my car with the same tune on 91 with no drama but I wasn't drag racing it either.
 

victorofhavoc

Autocross Champion
Location
Kansas City
Ethanol isn't really higher octane so by mixing in e to 91 you don't necessarily raise octane. E has benefit when you dump more fuel in, which requires retune to account like others are saying.

If you want to go from 91 to 93.6 Oct without retuning you can mix 1gallon of toluene paint thinner (home depot racing sells it) with 9 gallons of 91. Other option is to run Lucas octane booster (large bottle) in 10 gallons of 91. This will make approximately 93.1 oct.

Edit: I should add that neither of these options is cheap and will basically account for an additional $1.5-2/gallon. Detune would be cheaper in the long run, but if you're in a pinch...
 

dtfd

Go Kart Champion
Location
Chicago
Car(s)
MK7.5 GTI
Ethanol isn't really higher octane so by mixing in e to 91 you don't necessarily raise octane. E has benefit when you dump more fuel in, which requires retune to account like others are saying.

If you want to go from 91 to 93.6 Oct without retuning you can mix 1gallon of toluene paint thinner (home depot racing sells it) with 9 gallons of 91. Other option is to run Lucas octane booster (large bottle) in 10 gallons of 91. This will make approximately 93.1 oct.

Edit: I should add that neither of these options is cheap and will basically account for an additional $1.5-2/gallon. Detune would be cheaper in the long run, but if you're in a pinch...
pouring literal paint thinner into your car just sounds like a terrible idea.

imagine if you spill while doing that.....
 

jimlloyd40

Autocross Champion
Location
Phoenix
Car(s)
2018 SE DSG
pouring literal paint thinner into your car just sounds like a terrible idea.

imagine if you spill while doing that.....
Toluene is a great fuel injector cleaner and carbon cleaner, the entire fuel system. Like you said just don't get it on painted surfaces.
 

tigeo

Autocross Champion
Ethanol isn't really higher octane so by mixing in e to 91 you don't necessarily raise octane. E has benefit when you dump more fuel in, which requires retune to account like others are saying.

If you want to go from 91 to 93.6 Oct without retuning you can mix 1gallon of toluene paint thinner (home depot racing sells it) with 9 gallons of 91. Other option is to run Lucas octane booster (large bottle) in 10 gallons of 91. This will make approximately 93.1 oct.

Edit: I should add that neither of these options is cheap and will basically account for an additional $1.5-2/gallon. Detune would be cheaper in the long run, but if you're in a pinch...
The Uni tunes will easily handle 20-30% (depending on IS20 or 38) in my experience with no issues/need to re-tune.
 

tigeo

Autocross Champion
Ethanol isn't really higher octane so by mixing in e to 91 you don't necessarily raise octane. E has benefit when you dump more fuel in, which requires retune to account like others are saying.

If you want to go from 91 to 93.6 Oct without retuning you can mix 1gallon of toluene paint thinner (home depot racing sells it) with 9 gallons of 91. Other option is to run Lucas octane booster (large bottle) in 10 gallons of 91. This will make approximately 93.1 oct.

Edit: I should add that neither of these options is cheap and will basically account for an additional $1.5-2/gallon. Detune would be cheaper in the long run, but if you're in a pinch...
E85 is higher octane rated than 93. The "flex fuel" I get at Sheetz says 94 on the pump but this is likely based on the lowest e content they advertise (40 or so).
 

tigeo

Autocross Champion
You're right, I mistated. High oct, but lower BTU.
Correct - need more volume for same power basically hence the need for a fuelling system that can deliver that higher volume.
 

odessa.filez

Autocross Newbie
Location
Roswell, GA
Car(s)
2016 GSW 1.8tsi auto
I'm on the Lowe's Racing website now.

Does toulene require more fueling headroom, similar to e85?.Any downside to running a.ratio stronger than 1 to 10?

I wouldn't mind an extra octane point or two, now and then.
 
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