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ECMlink E85 MaxOctTable

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AWD-Tony

Proven Member
6,801
3,735
Sep 11, 2017
Cincinnati, Ohio
So I'm all set to go e85 but still have a full tank of 93. Please take a look at the maxocttable I've created and tell me what you think. I still want to smooth it out a bit but want to make sure I'm on the correct path.

Thanks for the input!
Tony
 

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You will want it just like gasoline Tony. I tune cruise and idle to 14.5ish. Shoot for that and see if you like it.
 
You will want it just like gasoline Tony. I tune cruise and idle to 14.5ish. Shoot for that and see if you like it.

Thanks Marty! I must not be understanding the articles on e85. I’ll have to go through it again.
 
You account for that difference in the global fuel calculation if I recall.

I know I have to adjust global by multiplying my inj x .67. So are you saying I can leave the rest of my fuel settings the way they are? I’ve read wot afr should be between 11-12.8 on e85.
 
Yes, the WOT should be 11.0 - 12.0 (which is getting kind of lean). Change the stoich in the fuel tab to 9.8:1 instead of 14.7:1.
When you lean out too much, you do get power but a hella lot of heat also as my exhaust was glowing RED when I ran 12.5-12.9 up top under WOT so try to keep it to 12.0 or just under for safety sake.
 
Yes, the WOT should be 11.0 - 12.0 (which is getting kind of lean). Change the stoich in the fuel tab to 9.8:1 instead of 14.7:1.
When you lean out too much, you do get power but a hella lot of heat also as my exhaust was glowing RED when I ran 12.5-12.9 up top under WOT so try to keep it to 12.0 or just under for safety sake.

Oh I see. Probably take a while for me to go through a full tank and get it fully tuned on corn.

Thanks, Guys!!
 
Are you on Speed Density Tony? If so, go cruise and let SDAdjust help you get it dialed in. Right click on the log and then click on SDAdjust and apply the table recommended, then do it over and over until you like the way she runs.
Remember to reset your fuel trims in between.
 
Well hell.....I am not as good on a MAF as I used to be since I converted all 3 of our DSM's to SD. Sorry man! :ohdamn:
 
Well hell.....I am not as good on a MAF as I used to be since I converted all 3 of our DSM's to SD. Sorry man! :ohdamn:

No worries man! I’ll be happy with 15 more horse puppies. Appreciate the input Marty!!
 
Are you on Speed Density Tony? If so, go cruise and let SDAdjust help you get it dialed in. Right click on the log and then click on SDAdjust and apply the table recommended, then do it over and over until you like the way she runs.
Remember to reset your fuel trims in between.

It has the same for maf, so I’ll use that for cruise.
 
LOL..my bad. Thought 9.8 is where you'd want it for cruise and idle. Thanks Vegas!!

This would be correct If you were looking purely at ethanol afr scale, then stoichiometric of E85 is correct at 9.8. But unfortunately all tuning in DSMLink is in gasoline scale so 14.7 is what you still have to use and stick to.

Change the stoich in the fuel tab to 9.8:1 instead of 14.7:1.

No, you can't do this. DSMLink only understands gasoline afr scale. If you tried this it would be running pig rich in closed loop. You have to keep it at gasoline stoichiometric of 14.7.
 
This would be correct If you were looking purely at ethanol afr scale, then stoichiometric of E85 is correct at 9.8. But unfortunately all tuning in DSMLink is in gasoline scale so 14.7 is what you still have to use and stick to.



No, you can't do this. DSMLink only understands gasoline afr scale. If you tried this it would be running pig rich in closed loop. You have to keep it at gasoline stoichiometric of 14.7.
Well that is how I tune and it works just fine. Why do you think that option is in link? Just asking.
My AFR's are displayed in gas scale but I DO have my stoich changed, in fact, it is the only thing I changed when I went to E85 at a station 30 miles away. Was the tune perfect, no. Did it run ok and get me home until I could fiddle with the tune, hell yeh! :thumb:
 
If you're using narrowband simulation, then the voltage switchover is really what DSMLink is using to keep stoichiometric in closed loop. But for sure in maxoct or minoct tuning you can't put 9.8 in any of those cells and expect to be at stoichiometric.
 
This would be correct If you were looking purely at ethanol afr scale, then stoichiometric of E85 is correct at 9.8. But unfortunately all tuning in DSMLink is in gasoline scale so 14.7 is what you still have to use and stick to.



No, you can't do this. DSMLink only understands gasoline afr scale. If you tried this it would be running pig rich in closed loop. You have to keep it at gasoline stoichiometric of 14.7.
He's referring to the global fuel calculator under the fuel tab. It's only used to calculate your new global when switching to e85.
 
Thank you Vegas, yes that was all I was referring to. Good lord if I plugged 9.8 into any cell it would die immediately because it's flooding.
Sorry for the confusion!
 
9.8:1 IS stoich for E85 if you're tuning on a ethanol scale (9.0:1 is stoich for E100), your WB (unless you have a special ethanol WB) reads stoich on the gasoline scale which is what you'll tune to even if you're running ethanol. If you plug 9.8:1 in your idle cells it really doesn't do much since that's the OLMax/MinOct table which means the ECU only pulls that info when the car's operating in open loop and idle/cruise you're running in closed loop and the narrowband sensor is controlling your AFR's which it targets 14.7:1.

Look at the OLMax/MinOct tables as a graph with x and y axis, the y-axis is rpm of course and the x-axis is load factor (0.3 to 3.4) which roughly translates to your boost level (with some more complicated math) so really it's what AFR's are you targeting at XX psi @ X k rpm.

Load Factor (for reference only, it's not exact)
0.3 to 0.7 is in vacuum, < 0psi or < 14.7psia
1.0 is ~5 psi
1.4 is ~8psi
2.0 is ~17psi
2.4 is ~23psi
3.0 is ~35psi
3.4 is 40psi​

I run a richer ethanol AFR (11.5:1 by 23psi @ 4k) than most because Arizona ethanol is actually E54 (not 85) so it has a lower octane rating, some run 12:1 out to 12.5:1 depending on how lean they're willing to go. So, looking at my OLMaxOct table below and using the estimated boost vs load factor rows you can get an idea of what AFR I'm trying to target on a gasoline scale.

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The tricky part is tuning the MAFComp or Speed Density table to get your AFRatioEst to lineup with your WB so you're hitting these target AFR's throughout the rpm band at any boost level. :sneaky:
 
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