default ignition trim flex fuel

[savagerocco]

I have been messing around making sure my maps are all correct and starting off from the default msq shipped with the alphas. I have noticed that the ignition timing under 100% ethanol shows -13 degrees, when in reality, I like to add about 15 degrees timing to the 100% ethanol settings. I am assuming that it is an issue where it isn't available for testing over in the UK.... what were the thoughts behind that default value?

[Matt Cramer]

The number is subtracted, so the -13 means it's actually 13 degrees more advance. Not sure why they did that, but it's been that way since the B&G days.

[savagerocco]

getting caught thinking in the box again......

[savagerocco]

Well, I can confirm that the negative numbers takes timing away..... Had to change that number to positive... gues it was changed..

[ianferrell]

I changed mine to +4.5 and can confirm that + is the way you want to go. Having a default of 3-5 probably makes a lot more sense than '-13' Also of note, I think the default of 165% adder for 100% ethanol is a good bit past liberal, I dropped mine to 155 and its still quite a bit too rich.

Also, I'd like to put in another vote for 'we need table blending' This fixed percentage stuff is just not good enough in the real world. I didn't spend just a ton of time tweaking the adjustment percentage, but there didn't seem to be a happy median that made my 93 oct map 'just work' with extra fuel. I know its on the todo list etc, just putting my vote in for table blending.

[S.Bretz]

I have read in my research on ethanol that the flame travel a little faster than gasoline. I assumed that is why they stared with pulling out timing so that you can add it back it. Also, having the 100% ethanol blend a bit richer is good since the power mixture in ethanol is a bit richer in terms of the lambda reading. I turned mine down to 158% though and left my timing at -2% and still saw some slight, consistant gains on the dyno.

Can you get away with more timing...In some cases YES since the eth is acting as a chemical intercooler. But I would not add timign across the board. I would adjust it in on the timing maps as the load will more effect on where you can add the timing.

[savagerocco]

I am running about 10+ timing added to my map and seeing nice power increases. It also helps with my fuel milage which sucks on e85 anyways.

[Token]

Look forward to using the flex fuel feature with the MS3x, but the sensor is $$$!

I read recently about some OEs avoiding the cost of the sensor by simply using o2 feedback to figure out fuel content. Has its pros and cons. Link here- http://www.siucautomotive.com/presentations/flexfuel.pdf

Wondering if there are plans to put this logic into the flex fuel feature. It would interfere possibly with other systems in place, possibly a/f warning, EGO feedback limits etc, but is sure nice to possibly avoid the $400 sensor.

[racingmini_mtl]

OEMs have complete control over the O2 sensor setup and its calibration not to mention the rest of the engine control and management. This is very far from the case with Megasquirt. Implementing a flex fuel algorithm based on an unknown would be problematic. And that's a huge understatement.

Jean

[piledriver]

OEMs have complete control over the O2 sensor setup and its calibration not to mention the rest of the engine control and management. This is very far from the case with Megasquirt. Implementing a flex fuel algorithm based on an unknown would be problematic. And that's a huge understatement.

Jean

Perhaps not in the MS code itself...
Would it be more possible if TS or MLV had a calculator built in, and could manually set some variable?
I realize it would require tweaking for each setup, but so does everything.

For folks who want/need a feature like this, a carputer etc would be NBD, and using the WB and some known fuel flow seems likely to be more reliable/consistent than the $300 sensors.