Fuel Quality and IAM
 

I used to believe that for the most part fuel was fuel and that other than a detergent or additive package at the depot level for the most part it was essentially the same quality and would have little effect on the enduser.


I say this with some experience working in an analytical lab and analyzing soil samples for leakage from fuel tanks. So I have some basic understanding of the components in gasoline and the ranges we can expect to see.


Ever since I purchased my OpenFlashTablet I have been collecting data logs whenever I drive my car. Not for any specific purpose in regards to tuning, but rather just to get a basic understanding of what is going on in respect to knock and timing.



Also, I am in Washington state so the best we have available is 92 Octane with up to 10% ethanol. I have tried 92 ethanol free even and it causes IAM to drop here. No 93 Octane available. E85 on a tune also works real well, but it's not convenient to use all the time.

I have a log book going back to my very first car. I can tell you where I purchased fuel, how much I purchased and what I paid for it, also any maintenance that was performed. I grew up around airplanes and logbooks were just something that is procedure.


Anyway, to my point. I have identified one fuel station and a specific pump that will not cause my IAM to drop below 1.00 It is a local Cheveron station. I have purchased fuel from another Cheveron station and after a few miles IAM has dropped to .82 I get similar results from a local Shell station. When I return to the first Cheveron station my IAM will eventually climb back to 1.00 and stay. I've been able to reproduce this several times and have purposely fueled elsewhere to see IAM drop and then gone back to the Good Cheveron and it will return to 1.00


In the case of the good IAM data I purchse from the same station, same pump # everytime. The next step I will try is a different pump at the same station and see what happens.


This all came about because I was interested in MAF scaling and began logging parameters that would be appropriate and collecting data. Now it has become more of a search for the best quality fuel available.


Don't really have a point to my post, but rather just sharing some information. What have others of you experienced?

It's likely that all fuel from that station will be "good". It's more than likely that they use enough to get regular refills and therefore the supplied fuel is always being replaced. Would be interesting to know if the fuel comes from different depots even for similar local branded chains. Here in the UK there are only a couple of refineries so all V-Power or other branded SUL come from the same source so as long as the stations have regular replacements the quality is the same countrywide.

This is something I followed when I owned my OFT. I am in Cali and the best we get is 91OCT. I use to drive 6-8hrs to go from Vallejo to Santa Barbara, which required a refill to make the final leg of the journey.

After watching IAM dropping as low as .6, I only used one station about half way through the trip. I know live in SB and only use one Chevron station.

Fuel quality seems to vary a lot at individual pumps except the one i know go to. Don't really have a point as well, but goes to show that fuel can vary greatly from manufacturer to pump to pump.

I agree with @Kodename47 to a degree. the station I ended up with is off a major On/Off ramp to 101 and is regularly busy, with regular refills.

OFT is a great tool, even if your not using it for tuning.

I used to go to Shell but it dropped IAM to .7x so i switched to Sunoco and back to 1 all time.

Around me shell is the only one that keeps my IAM at 1 :iono:
The eternal search for the best gas continues lol

It's interesting how the brands of fuel can vary from location to location. Can't wait for some warmer weather so I can get back on E85.