GAS/E85 mode switching, appreciate a look

[NJ_Phil]

Switching into E85 "mode" , not actually running E85. Either 0% or 100% to keep it simple.
Tune and scan look great at idle when switching in and out, no change in spark, EQ command or AFR since no Alcohol adders setup yet, didn't check PE yet.

Stock OS/MAF enabled to 4k

Just want to make sure I didn't miss anything, seemed way too easy.

Thanks

[schpenxel]

I don't understand what you're trying to do but the one thing most people miss when trying to add/subtract spark based on ethanol content is under spark-->advance-->mult. vs composition. It's all 0's right now.

Basically the flex fuel spark table x the value in this table (dependent on ethanol content) = amount of spark added/subtracted, so keep that in mind when trying to make it add/subtract spark, if you do go that route.

Are you doing a meth safety setup?

[sevinn]

I don't understand what you're trying to do but the one thing most people miss when trying to add/subtract spark based on ethanol content is under spark-->advance-->mult. vs composition. It's all 0's right now.

Basically the flex fuel spark table x the value in this table (dependent on ethanol content) = amount of spark added/subtracted, so keep that in mind when trying to make it add/subtract spark, if you do go that route.

Are you doing a meth safety setup?

Another thing I've noticed is that the mult vs comp doesn't seem to interpolate between the values you put in the table, so for safety I have mine set to 0 in the 0-25% cells and then I match the header percent for the rest of the table.

[schpenxel]

Sometimes I put the 75/100 columns the same so if I tune something on E75'ish it doesn't add more timing if someone gets a hold of some E85 or higher also.

I've never noticed it not interpolating? Maybe I haven't looked closely enough

[sevinn]

Sometimes I put the 75/100 columns the same so if I tune something on E75'ish it doesn't add more timing if someone gets a hold of some E85 or higher also.

I've never noticed it not interpolating? Maybe I haven't looked closely enough

My specific case was when I had some e35 or so in the car and it was putting 50% of my spark adder. Granted it didn't knock, but it still made me uncomfortable enough to set it up that way.

[NJ_Phil]

The intent is to basically have a low and high performance mode for the car. Low performance would be no meth, "safe" spark table for reduced boost, and stage 1 fuel system OFF. Switching into hi-perf mode will enable alky, switch into "e85 mode" by sending 150hz into Pin 50 of the ECM for different spark and fueling. So the plan for the tune is to set the main spark table and fueling up for low perf setup, then either switch to a completely different spark table or alter the main table with a alcohol multiplier. I Just left everything spark related at 0 for now and set 14.7 across the board for stoich in the AFR table to make sure there was no change in spark and fuel when I switched in and out of modes. Meth fail safety should be automatic since the system stays in low perf mode until the Alkycontroller's Grey wire goes hot to indicating flow. So a manual switch enables meth, meth flow enables high perf mode

Example:
Main spark table = 23* for 4000 RPM @ 1g Cylander airmass
Flex fuel spark or alcohol adder = 8* for that corresponding RPM/Airmass

High Perf mode gets me 31* spark

EDIT: You guys are lucky to have E85..It's not available here in NJ but we do get 93 + 10% Ethanol

[schpenxel]

Is the gray wire active just when the pump is running or when there's pressure? It won't really confirm meth flowing if it's just on when the pump is supposed to be running, though it's certainly better than nothing.

Yeah the spark part isn't hard--fuel is a little trickier but you should be able to figure it out. Might have to do a little PE (alcohol) tweaking to make it work out right.

When I ran 93+meth I built a device that varied "alcohol %" based on methanol pressure (added a pressure sensor to meth system). Pretty cool setup but had to get rid of it when I went to E85. I'm getting a whopping 16mpg here lately on E85

[NJ_Phil]

I think Julio has some sensing circuit on the PAC to detect high motor current, indicating pressure in the line. Empty tank, open line, etc, means no current, no activation. It probably takes a few 100ms to build pressure and the grey wire "signal" comes on with pressure, so no early spark and chance of knock, at least that's what I'm hoping. Unfortunately, a plugged line doesn't get detected but at some point you have to stop thinking "what if?" and keep one eye on the WB at all times. I'll plot the whole meth on, spark and PE with the scanner to prove things out and might even do a 2 step controller to run 50% Alcohol settings for meth only, then 100% for a small 50 or 100 NOS dry shot.

Not sure what E85 costs but I think it's cheaper than 93 so dollars per gallon might be the same. You sent me the schematic for that small Atmel PCB a while back and it was really cool.

I'll post back a scan and tune of the whole setup after it's done.

[schpenxel]

True, true... at some point you just have to go with it. I've thought about doing a flow meter but the only ones I could find that would handle 100% meth were some ones at work that are like $2K+.. not quite worth that much!

Yeah $/mile it's about the same as 93, maybe a little cheaper even. E85 is something like $1.89 a gallon here right now (was $1.60 not long ago) where premium is more like $2.50, so it's pretty close