Regular Vs. Premium Fuel

I haven't read this thread, but I wanted to share a quick data point about the Civic Si that I just bought yesterday (new). I did some datalogging with a FlashPro, and was blown away by the amount of knock retard that the ECU is applying across the whole rev range. It's around 10 degrees retard for most of the range, which results in a about 15 degrees advance until it gets to 6K, then it climbs a few degrees as knock retard tapers a bit. It also runs uber-rich, maxing out the AF sensor at 10 above 5500. Torque drops off HUGE as well, which causes HP to go flat from 5500 to redline. I've only put about 150 miles on it so far, so I guess it's possible that Honda implemented some sort of "mileage compensation" in the tune that makes it perform poorly during break-in, but I really doubt that. I think it's much more likely that the dealership just put low octane fuel in it. I will definitely put high quality high octane fuel in it when I run this fuel out, and will see how that changes things.
 
This is a great thread indeed. I, for one, am sick of the whole "regular" vs. "premium" naming scheme as it makes those less inclined to believe premium is better quality vs. regular (and can we just please stop selling Plus/Mid-grade since not a single car uses it). This day and age, all grades have the same concentration of additives so the whole notion of "premium" is just a marketing ploy to sucker in those who don't understand what octane is really for.
 
I finally finished the tank of bad gas from the dealership last night, and filled it back up with 93 octane. I started datalogging on the FlashPro before I drove away from the pump, and immediately went to my special dyno spot (on private property in Mexico) to do a bunch of pulls. I couldn't believe how quickly the ECU adjusted to the new fuel. The K. Control value was at 99% when I left the gas station, but it dropped to about 50% within minutes. As expected, the knock retard dropped by about half too, so instead of 10 degrees of knock retard, I was getting about 5 degrees. The torque curve also improved by 4-8 ft-lbs, and power above 6K was much better. However, it's still disappointing in the upper RPMs. I will do some more pulls tonight to see if a day of driving with good gas will cause the ECU to adjust even further.
 
Gernby said:
I finally finished the tank of bad gas from the dealership last night, and filled it back up with 93 octane. I started datalogging on the FlashPro before I drove away from the pump, and immediately went to my special dyno spot (on private property in Mexico) to do a bunch of pulls. I couldn't believe how quickly the ECU adjusted to the new fuel. The K. Control value was at 99% when I left the gas station, but it dropped to about 50% within minutes. As expected, the knock retard dropped by about half too, so instead of 10 degrees of knock retard, I was getting about 5 degrees. The torque curve also improved by 4-8 ft-lbs, and power above 6K was much better. However, it's still disappointing in the upper RPMs. I will do some more pulls tonight to see if a day of driving with good gas will cause the ECU to adjust even further.
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This is some excellent data to show why not using the recommended octane is a bad idea in an Si. Keep us updated as you run completely through this tank of gas. Thank you!
 
Gernby said:
I finally finished the tank of bad gas from the dealership last night, and filled it back up with 93 octane. I started datalogging on the FlashPro before I drove away from the pump, and immediately went to my special dyno spot (on private property in Mexico) to do a bunch of pulls. I couldn't believe how quickly the ECU adjusted to the new fuel. The K. Control value was at 99% when I left the gas station, but it dropped to about 50% within minutes. As expected, the knock retard dropped by about half too, so instead of 10 degrees of knock retard, I was getting about 5 degrees. The torque curve also improved by 4-8 ft-lbs, and power above 6K was much better. However, it's still disappointing in the upper RPMs. I will do some more pulls tonight to see if a day of driving with good gas will cause the ECU to adjust even further.
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Great info!
Was the initial run with the stock tune or the FP base tune?
Wondering if "crappy" or old gas was reason for the original readings? (But then again, I'm not sure I'd want to hammer a new Si before it's broken in.)
Have others provided this type of info relating to knock & retard vs fuel octane?
Perhaps Vit can chime in.

Note: The Hondata Reflash FAQ article says 87 works on the K-series and 93 is only for the "last few" HP. Assume FP would be about the same.
And, YES I'm an 87er who wanted a stick sedan with sunroof, but have no complaints about choosing the '12 Si!
 
tacthecat said:
And, YES I'm an 87er who wanted a stick sedan with sunroof, but have no complaints about choosing the '12 Si!
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Doesn't the EX come with stick and moonroof? ;-)

I personally wanted stick & navi, and the dealer convinced me to go for the Si. I wish they had the touring in stick, as I really miss having leather interior :-(
 
Monk said:
There's a cleaner I like called "Seafoam" and can be used in the fuel tank, as well as the oil sump. I've used it in my Jeep and had some clicking noise that went away with about 4 oz. of the stuff in my fuel, and would do that about every month or so............. with my MC I use it about 1 oz with every tank(5+ gal tank)(so about 2 oz to 10 gal seems to work). Also on my MC I have a "Oil window" for checking the oil level and though time could see the window getting that tinted colour, so right before changing my oil I put about 4 oz. in the sump and went for a 30 mile ride, came home and changed the oil ....Clean window...... that's all I know.........
There are plenty of cleaners out there that are good.... this is the one I use.
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You can actually run Seafoam in your oil for a 1000 miles with no problem... It is Silicone based and is great for the seal and upgrades the oil. (Great for sticking lifters, hence the clicking noise) Read up on it. Don't go off of hear say...
 
Great info @Gernby ! Tagging this for any updates - I just got my '13 Si new with 120 miles on it in early December. You mentioned disappointing power above 6k RPM and I'd been thinking the same thing at first. My car just rolled over 5,000 miles (work travel, hurts to think about lol) and the power up top still seems to be improving. Once you get a couple thousand miles on it, let us know if the power in the higher revs improves!
 
carpenj said:
Great info @Gernby ! Tagging this for any updates - I just got my '13 Si new with 120 miles on it in early December. You mentioned disappointing power above 6k RPM and I'd been thinking the same thing at first. My car just rolled over 5,000 miles (work travel, hurts to think about lol) and the power up top still seems to be improving. Once you get a couple thousand miles on it, let us know if the power in the higher revs improves!
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I hit 2500 miles (all highway) and the car is feeling a bit quicker all around. I do not beat on my car a drive it nice! I have kids and they are always in the car. Yesterday I was merging onto to the highway and just rolled out 3rd and 4th and ****! With a drop in K&N, Exhaust Resonator Delete and Intake Res Delete it got up and went. It was fun as hell! Now at 3200 miles it is driving better and better everyday.
 
Gernby said:
I finally finished the tank of bad gas from the dealership last night, and filled it back up with 93 octane. I started datalogging on the FlashPro before I drove away from the pump, and immediately went to my special dyno spot (on private property in Mexico) to do a bunch of pulls. I couldn't believe how quickly the ECU adjusted to the new fuel. The K. Control value was at 99% when I left the gas station, but it dropped to about 50% within minutes. As expected, the knock retard dropped by about half too, so instead of 10 degrees of knock retard, I was getting about 5 degrees. The torque curve also improved by 4-8 ft-lbs, and power above 6K was much better. However, it's still disappointing in the upper RPMs. I will do some more pulls tonight to see if a day of driving with good gas will cause the ECU to adjust even further.
Click to expand...
I'm not sure if this is relevant but isn't Mexican gas(PEMEX) different than US gas? Somewhere I read that Mexico gas gives a little more HP?
 
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