sawedoff

iTrader: (3)

I don't remember where I may have read this, or if I even read it correctly. Does the ECM have the ability to read an octane rating above 94? I did notice that the car never felt that much different even with high quality race fuel that was way above 94, and I figured that the computer was not programmed to adjust timing to adjust for this. I am interested in this detail. I am wanting to experiment with some fuel doping compounds/formulas, and would like to be productive in my endeavor. If it doesn't, is there anyway to modify the ECM to do this? These compounds are not the cheap shelf brands that you'd encounter at speedhops or parts counters, and they don't come in little bottles either. This stuff can in no way be associated with that stuff or fuel cleaners. I just thought I'd clarify that point before I get responses geared to that angle. Thanks.

jimmyblue

iTrader: (11)

Does it read it at all? I thought it just adapted and reduced
the spark (by interpolating between high & low tables) if it
got too much knock detect over time.

If you just jacked up the spark in the high octane table you
would over time adapt to the race or street fuel. But I think
the downhill ride happens a lot faster than uphill (only reset
by major fuel level increase?).

wrencher

iTrader: (2)

The only thing the PCM would "see/read" is a low occurance of knock.
It would just run the higher tables, so if you want to take advantage of the octane, you'll need LS1 edit help.

emarkay

PCM cannot tell your octane, only if there is acoustic detonation - an indicator of preigniton. Knock can also be caused by other things and "false knock" can fool the knock sensors into "thinking" there is detonation. There is NO "resetting of the "octane tables" by adding fuel or ANY other means, other than a non occurance of knock.

Are you planning to study petrochemical engineering? There are many variables in the science of hydrocarbon combustion, going all the way back to Kettering and the Ethyl Corp. in the 1920's. Just do some Googling or library research to insure you are not reinventing the wheel, or damaging your chromosomes!

For more info on the Adaptive Spark and Knock Sensor routines, a good start is this link...

http://www.efilive.com/forum/viewtopic.php?t=298

wrencher

iTrader: (2)

? LS1 edit?can definately help.

sawedoff

iTrader: (3)

Okay, you guys have definitely helped me in this. I realize that the ECM has no way to actually measure the octane of fuel, at least not yet. I figured they had done a national average of premium fuel octane ratings and used that when they designed the program for the map. Wrencher may have hit it right, on the LS1 Edit. Is there anyway to do a table so that you could reap the benefits of using hgher octane fuel?

emarkay

Higher octane will LOWER performance in most modern engines that are basically unmodified to take advantage of the slower flame front. Unless you are putting near Diesel-like CR in the cylinders, "93 octane" or so is all you need!

Manupulating the advance only controls a very limited amount of variables in getting power from combustion, and there are MANY more cost and time effective ways to get power in a IC engine!

wrencher

iTrader: (2)

Engines make max power at WOT at the edge of detonation with optimized fuel ratio's.
sawedoff go here & check out their info on edit;
www.carputing.com
www.installuniversity.com
www.slowcar.net